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Proposal Number: 09100452

Title: High Resolution Imaging and Spectroscopy of 8P/Tuttle

PI Name: Damian Christian

Type: GO

We proposal a 50 ksec ACIS-S observation of the brightest known comet available during Chandra Cycle 9, 8P/Tuttle (2008). The comet will have close passage by the Earth in January 2008, with minimum Earth-comet distance of 0.25 AU and maximum visual brightness V~5.9. We will: search for changes in the spectra as a function of distance from the comet's nucleus and spectral changes across the x-ray bow shock; 2) investigate the spectral changes as a function of changes in the Solar Wind (such as, composition, velocity, and type) by comparing our results with real time solar wind monitors on board ACE, SOHO and STEREO; and 3) test the latest self-consistent physics-based charge exchange models model against the ACIS-S spectra and derive minor ion abundances.

Proposal Number: 09200028

Title: Search for triggered star formation in the unique bright rimmed cloud 4

PI Name: Gordon Garmire

Type: GTO

In order to further our understanding of the radiation driven implosion (RDI) processes and provide an observational feedback to the theoretical modelling of these processes for a wide range of parameters, we propose to search for and study triggered star formation in the highly under-pressured with respect to its ionized boundary layer and one of the smallest among the known cataloged bright rimmed clouds (BRCs), BRC 4. The data and science analyses similar to those applied in our study of the BRC 38 (= IC 1396N) will be employed.

Proposal Number: 09200053

Title: ACIS Mapping Observation of W75N/DR21

PI Name: Gordon Garmire

Type: GTO

W75N/DR21 is a complex of several massive star-forming regions at a distance of 2-3 kpc in Cygnus. Recent wide-field imaging survey program using Spitzer/IRAC, UKIRT/WFCAM, and JCMT/SCUBA revealed the entire picture of this complex, which is filled with various signatures of massive star birth. The central part of the complex, DR21, is scheduled to be observed by a deep ACIS-I pointing in the cycle 8. By adding two more ACIS-I pointings, we will cover all the major regions in this complex. The primary objective is to conduct a census of weak-line T Tauri stars using their elevated X-ray emission. By combining with the longer wavelength datasets that are sensitive to less evolved population, we will understand how the star formation proceeded in this region.

Proposal Number: 09200063

Title: X-Raying the debris disk of AU Mic

PI Name: Peter Predehl

Type: GTO

We propose to measure the X-ray absorption by AU Mic s debris disk as well a high resolution spectrum of a flare star which allows us to perform density diagnostics in the N, O, and Ne triplet lines as well as perfrom an abundance analysis of the CNO elements.

Proposal Number: 09200064

Title: The HETG Orion Legacy Project: The Periastron Passage of Theta1 OriC's Massive Secondary

PI Name: Claude Canizares

Type: GTO

The Trapezium Cluster is one of the youngest and closest (440 pc) star-forming regions. Many of the properties we know today are derived from X-ray signatures. This program has two goals. First we study highly resolved X-ray spectra of a large ensemble of very young and chemically similar PMS stars in terms of their magnetic and accretion properties. It is part of our HETG Orion Legacy Project which amouts to 430 ks by the end of AO8. This portion has a second purpose which aims to record the post-periastron passage of the recently discovered massive secondary of Theta 1 Ori C. Orion cannot be observed until midJuly 2007 from which on we will be able to record possible shock emission from colliding wind events or interacting magnetic fields.

Proposal Number: 09200065

Title: The HETG Orion Legacy Project: PMS Stellar Studies of the Orion Trapezium Cluster

PI Name: Claude Canizares

Type: GTO

The Trapezium Cluster at the center of the Orion Nebula Cluster (ONC) is one of the youngest and closest (440 pc) star-forming regions. Many of the properties we know today are derived from X-ray signatures. Here we study highly resolved X-ray spectra of a large ensemble of very young and chemically similar PMS stars in terms of their magnetic and accretion properties. This is the forth of several installments of our Orion HETG Legacy Program, which already amounts to 430 ks by the end of AO8. There are two installments of 75 ks in AO9. This is the second installment which will lead to the final exposure of the project of 580 ks. On completion we expect about a dozen of well exposed HETG PMS star spectra and HETG Trapezium spectra of supreme quality. .

Proposal Number: 09200079

Title: Protostars and Jets in Cep A

PI Name: Steven Pravdo

Type: GO

Cep A is a region of intense star formation with a well-studied bi-polar molecular outflow, the nearest identified high-mass protostars, and X-ray Herbig-Haro (HH) objects. Unresolved areas of X-ray emission make it a prime target for Chandra/ACIS-I. We propose an 80 ks observation to measure the spatial structure, spectrum, light curve, and intensity of the X-rays, including HWX, the unresolved X-ray candidate for the power source, and to identify counterparts. The goal is to increase our understanding of the energy sources and the outflows. We will also image a nearby ridge of hard X-ray emission to investigate its origin. We will use Chandra s superior spatial resolution to clarify the puzzling offsets between the X-ray emission and the areas of peak optical excitation in HH 168.

Proposal Number: 09200137

Title: Resolving the Xi Boo Binary

PI Name: Brian Wood

Type: GO

Due to its close proximity (d=6.7 pc), the primary of the Xi Boo binary (G8 V+K4 V) is one of the best targets for studying the coronal characteristics of moderately active stars. However, previous X-ray observations of Xi Boo are complicated by their inability to separate the emissions of the two stars. We propose to obtain LETG/HRC-S spectra of Xi Boo, which will easily resolve the stars and provide high quality spectra of both. We will then explore the nature of an apparent change in coronal character that exists at about the activity level of Xi Boo A by comparing the Xi Boo A spectrum with an existing LETGS spectrum of Epsilon Eri (K1 V), these two stars being on opposite sides of the transition.

Proposal Number: 09200153

Title: BP Psc: Chandra Takes a Close Look at a Pre-Main Sequence Star-Disk-Jet System

PI Name: Joel Kastner

Type: GO

Observational studies of disk-jet systems in pre-main sequence (PMS) stellar evolution provide insight into a diverse range of phenomena, including jet launching and collimation, protostellar accretion, and the formation and evolution of planetary systems. We propose to obtain Chandra/ACIS-S3 imaging spectroscopy of BP Psc, the only known actively accreting and jet-driving PMS star within 100 pc of Earth. These observations will take full advantage of this unparalleled opportunity to probe star-disk-jet interactions within ~30 AU of a PMS star, via X-rays.

Proposal Number: 09200162

Title: Are the Herbig Ae star HR 5999 and the peculiar A-type star HR 6000 X-ray emitter?

PI Name: Jan Robrade

Type: GO

We propose a 10 ksec pilot study with ACIS-I of the visual A-type binary HR 5999/HR 6000 located in the Lupus star forming region. HR 5999 is a X-ray bright Herbig Ae star, HR 6000 is a possibly magnetic X-ray bright A-type star. Both stars would be ideal grating targets. With the proposed ACIS pointing we want to verify that the X-ray emission does indeed come from the A-type stars.

Proposal Number: 09200198

Title: The coronae of ultracool dwarfs: Simultaneous X-ray and radio monitoring

PI Name: Beate Stelzer

Type: GO

In late-type stars the interaction of stellar magnetic fields with hot plasma trapped within the field lines gives rise to Halpha,X-ray and radio emission, as in the Sun. The coolest stars and brown dwarfs not follow this solar-stellar analogy: their radio emission tends to be overluminous by 3 dex with respect to their X-rays, and there is no clear rotation-activity connection. Possibly the situation in ultracool atmospheres is quite different from those of higher-mass stars, and new emission mechanisms need to be invoked. Since both radio and X-ray emission of these objects are strongly variable, the observational picture remains unclear as long as no simultaneous data is available in both bands. We propose here for joint Chandra/VLA observations of 3 ultracool dwarfs.

Proposal Number: 09200200

Title: Surveying Magnetic Activity in L and T Brown Dwarfs

PI Name: Marc Audard

Type: GO

We propose to continue our investigation of magnetic activity in L and T brown dwarfs in the X-rays with Chandra and in the radio with the VLA and ATCA. We propose to observe three brown dwarfs in the largely unexplored late-L and T regimes with Chandra. Our targets are close, old (~1 Gyr) brown dwarfs, whose Halpha emission should not be contaminated by any accretion mechanism as in young brown dwarfs. With this Chandra proposal, we aim to detect X-rays in brown dwarfs during quiescence or flares. Simultaneous radio observations with the VLA and ATCA are requested as well. This investigation will help us to obtain a census of magnetic activity in L and T brown dwarfs and to better understand the efficiency to generate magnetic fields at the bottom of the main sequence.

Proposal Number: 09200214

Title: NGC 3576: Spontaneous or Triggered Formation of a Giant HII Region

PI Name: Leisa Townsley

Type: GO

Our understanding of massive star formation is uncertain at all levels, from individual stars to massive stellar clusters to OB associations. Our first Chandra observation of the Galactic giant HII region NGC 3576 addressed one example of the first of these problems: because hard X-rays penetrate even very large columns of obscuring material, we were able to pinpoint massive, young, embedded stars that remained undetected even at 3.5 microns, solving the mystery of NGC 3576's missing ionizing sources. With a new ACIS-I pointing and the first Spitzer observation of this target, we will address the second two of these problems: how massive clusters form and how they are related to the formation and evolution of the larger-scale, unbound populations known as OB associations.

Proposal Number: 09200253

Title: The Further Fainting of Alpha Cen A

PI Name: Thomas Ayres

Type: GO

Alpha Centauri (G2V + K1V) is the nearest system of solar-like stars. The primary has long been regarded a solar twin. Previous X-ray missions have been able to separate the coronal point sources (14" apart in Y2000), although the orbit now is closing rapidly and beyond 2006 can only be resolved easily by Chandra. The 25 year X-ray record has revealed striking long term changes in the Alpha Cen coronae, likely related to analogs of the still mysterious solar sunspot cycle. Recent work suggests that the K star is falling into a cycle minimum, while the G star is relapsing following a brief recovery from an unprecedented deep X-ray minimum in 2005 (that fully challenges our understanding of stellar dynamos). Two 10 ks HRC-I snapshots in 2008 will build on this remarkable coronal narrative.

Proposal Number: 09200255

Title: A Survey of X-ray Emission from Nitrogen-rich Wolf-Rayet Stars

PI Name: Stephen Skinner

Type: GO

The winds of Wolf-Rayet (WR) stars enrich the ISM with heavy elements that will be recycled into future generations of stars and WR stars end their lives as supernovae, creating powerful shock waves that will trigger new star formation. Previous X-ray studies of WR stars have focused on X-ray bright WR+O binary systems and little is known about the origin of X-ray emission from single WR stars. We propose to conduct a limited survey of the closest known single nitrogen-rich (WN subtype) Wolf-Rayet stars. This study will complement a parallel survey of more evolved carbon-rich (WC subtype) WR stars now underway. This pilot survey will break new ground and will provide basic information on X-ray properties needed to test wind-shock theories.

Proposal Number: 09200257

Title: The clear view of WR140's collisionless shocks through the companion O-star wind

PI Name: Andrew Pollock

Type: GO

In January 2009, two extraordinary high-mass colliding-wind binary systems, eta Car and WR140, will go through the periastron passages of their respective 5.5 and 7.9 year orbits. The preceding months are the most favorable for observing the rapid rise to X-ray maximum and learning fundamental lessons about shocks, hot plasmas and mass-loss in the upper HR diagram. Three HETGS snapshot spectra of WR140 will capture the line-profile and global spectral responses of its collisionless shocks to the changing physical conditions that follow the well-defined orbital geometry, offering unique information about the plasma and mass loss from both stellar components. This proposal, and one on eta Car, will take advantage of opportunities for X-ray specroscopy that might not arise again.

Proposal Number: 09200270

Title: Filling in the Coronal Graveyard

PI Name: Thomas Ayres

Type: GO

20 ks Chandra HRC-I pointings on 5 late-type G/K supergiants in the depths of the "coronal graveyard" will complete a survey of the limits of X-ray activity in evolved cool stars. Our ambition is to gain insight into magnetic generation in the absence of sensible rotation, and the disposition of hot coronal structures in the extended outer envelopes of these objects, possibly partially smothered under a "cool absorber." Such buried activity might be the long sought initiator of chromospheric winds in the giant branch. Coronal activity is important to the Sun-Earth connection, the fate of primitive planetary atmospheres, and a broad reaching set of magnetic phenomena in diverse cosmic environments. Understanding the activity, and its evolution, is a key objective of stellar astrophysics.

Proposal Number: 09200326

Title: Search for X-Ray Emission from TW Hya Association Brown Dwarfs

PI Name: John Gizis

Type: GO

There are four known brown dwarfs which are members of the TW Hya Association (TWA). With an age of 10 Myr and a distance of only fifty parsecs, this association is the best opportunity to study young brown dwarfs in detail. Chandra has already observed two of the TWA brown dwarfs; we propose here to observe the other two. By doubling the sample, we will test ideas about coronal and chromospheric emission and about activity due to accretion from circumstellar disks. Spitzer observations for all of these brown dwarfs have been taken or are scheduled.

Proposal Number: 09200357

Title: Survey of Class 0 Protostars in the Smallest Clouds 'Bok Globules'

PI Name: Yohko Tsuboi

Type: GO

We propose a survey of six nearby Bok globules to search for X-rays from Class 0 protostars. X-rays from Young Stellar Objects are likely to originate from the near vicinity of the star itself. The detection of the X-rays from Class 0 protostars, therefore, is of particular importance, providing direct evidence that the central star has been born. However, protostars are usually deeply embedded within the cloud, so that, even the X-rays are completely absorbed. Bok globules are known as star formation sites surrounded by light and small molecular clouds of 10 Mo. The small absorption column of Bok globules provides us an opportunity to search for whether X-rays ``turn on'' during the Class 0 phase and if so, when?

Proposal Number: 09200403

Title: The Coolest X-ray Emitting White Dwarfs?

PI Name: Marcel Agueros

Type: GO

Among the ~6000 new white dwarfs (WDs) spectroscopically confirmed by the Sloan Digital Sky Survey (SDSS) are three cool DAs and two cool DBs within 1' of super-soft ROSAT All-Sky Survey (RASS) sources. WDs at these relatively low temperatures (<23,000 K) are not expected to be X-ray emitters, but the SDSS photometric and spectroscopic data fail to identify any other obvious optical counterparts to the RASS sources to the SDSS limits (g~22 mag in photometry). We propose a total of 25 ksec of Chandra observations of these five SDSS WDs to obtain pinpoint X-ray positions and improved flux measures for these objects. If Chandra data confirm that the five WDs are X-ray sources, they will be of great interest; in particular, work will be required to explain how such cool WDs can emit X rays.

Proposal Number: 09200488

Title: The Full Picture of Magnetic Activity in Ultracool Dwarfs: Simultaneous Observations of Coronae and Chromospheres

PI Name: Edo Berger

Type: GO

Only a decade ago, theoretical expectation was that magnetic activity would disappear beyond M5. While we now know that stellar activity exists in some late-M dwarfs, only a few such objects have been observed in the X-rays. Thus, the ubiquity and physics of coronae and magnetic fields remain unclear. This is exacerbated by the shift to flaring emission, whose properties are poorly characterized due to the lack of simultaneous observations. It is therefore time to produce a complete picture of the coronae and chromospheres in ultracool dwarfs, and directly implicate magnetic fields in this activity. Here we propose to delineate the underlying physics of the magnetic activity with fully simultaneous observations in the X-ray, radio, and H-alpha bands.

Proposal Number: 09200532

Title: X-raying the Giant HII Region G305

PI Name: Marc Gagne

Type: GO

G305, one of the nearest giant HII regions, contains a WR binary, eight distinct clusters each containing hundreds of stars and eight maser sources and ucHII regions each containing 4-8 very young O stars. The bubble contains ~30 O stars suggesting a population ~15,000 cluster members. A 125-ks ACIS exposure will detect all of the high-mass stars and a high fraction of the low-mass YSOs in the central clusters and HII regions. A 60-ks EPIC exposure will do the same in the sparser outer clusters and HII regions. The EPIC observation may detect diffuse emission in the inner cavity or within the optical HII region RCW 74. Our goals are to obtain ACIS and EPIC spectra of the high-mass stars, EPIC and RGS spectra of WR 48a, EPIC spectra of diffuse X-rays and a census of the low-mass YSOs.

Proposal Number: 09200535

Title: An Emerging Class of Hot Emission Line Stars: HD 119682

PI Name: Cara Rakowski

Type: GO

Herein we propose to observe the dispersed spectrum of the emission line star HD 119682. Existing CCD-resolution observations show this source to be both luminous and impressively hot, such that its emission cannot be explained by the standard radiatively-driven-wind model for O stars. At more the 4 Myr old, a magnetically confined wind would be unprecedented for a star of its age. Alternatively this may be an example of an emerging class of "gamma Cas analogs", emission-line early B stars with a narrow range of optical properties and X-ray spectra dominated by a hot (>8 keV) thermal component.

Proposal Number: 09200536

Title: ToO Studies with CXO of Pre-Main Sequence Stars Undergoing Optical Outbursts

PI Name: David Weintraub

Type: TOO

Dramatic optical outbursts, which signal the onset of rapid and dramatic accretion onto pre-main sequence stars through their disks, cannot be predicted; however, our previous CXO campaign to study the outburst source V1647 Ori demonstrates that studies of such stars made with CXO beginning immediately after outburst can dramatically increase our knowledge about how and why such stars undergo outbursts and accrete mass. We therefore propose a target of opportunity campaign to observe any such stars discovered during Cycle 9. We will use ACIS-S, to enable us to carry out 20ks - 30 ks imaging spectroscopy observations, spaced by intervals of two and later three months, beginning immediately after discovery and continuing through the end of Cycle 9.

Proposal Number: 09200559

Title: Effects of massive star radiation on circumstellar disks evolution in the Eagle Nebula

PI Name: Mario Guarcello

Type: GO

We will determine the frequency of disk and disk-less stars in the outer regions (relatively poor of massive stars) of the young cluster NGC 6611, with the aim to study the effects of UV flux due to massive stars on the evolution of circumstellar disks around low mass stars. Our previous results for the central region of the cluster show that this effect may be present, but we need to observe stars at larger distance from massive stars. This cluster is particularly well suited for our study, thanks to the irregular spatial distribution of its OB stars. CHANDRA observations are crucial for identifying the disk-less population undetectable with other method.

Proposal Number: 09200564

Title: X-ray and Radio Imaging of the Protostar Complex Adjacent to IC 348

PI Name: Scott Wolk

Type: GO

Among several classes of active stars and solar flares, a tight relation between X-ray and radio luminosities is found. This relation implies an intimate physical connection. We propose a pair of 40 ks coordinated VLA/ACIS-I observations of a newly revealed filamentary structure of nearly two dozen protostars and pre-stellar cores just southwest of IC 348. Using extant Spitzer and SCUBA data we have a full inventory of the stellar types in this cluster which contains Class 0 and Class I protostars and outflow sources in addition to classical and weak T-Tauri stars. We will complete the census of this nearby, actively forming, sub-cluster and study the causal relation of radio and X-ray emission for all types of young stars, both in flare and quiescent.

Proposal Number: 09200584

Title: Shock Dynamics in Eta Carinae Approaching the 2009 Periastron Passage: A Twisted Tail

PI Name: Michael Corcoran

Type: GO

In January 2009, the two most extraordinary high-mass colliding-wind binary systems, eta Car and WR140, will go through the periastron passages of their respective 5.5 and 7.9 year orbits. The months before, during their rapid rise to X-ray maximum, are the most favorable time for observing X-ray emission at high resolution and learning fundamental lessons about shocks, hot plasmas and mass-loss in the upper HR diagram. Three HETGS observations of Eta Car will monitor X-ray line and continuum changes to obtain unique information about the X-ray emitting plasma in the wind-wind collision, as a probe of mass loss from Eta Car and from the hidden companion star. This proposal, and a complementary one on WR 140, will take advantage of an opportunity that may never arise again.

Proposal Number: 09200644

Title: Polar Exploration and Coronal Structure in the Active Binary HR 5110

PI Name: Rachel Osten

Type: GO

Overwhelming evidence exists for the importance of polar regions in controlling stellar atmospheric structure and dynamics in active binary systems. Uncertainties about the geometry of coronal emission have made conclusions about coronal structures on such stars ambiguous. We seek Chandra, VLA and VLBA observations of the nearly pole-on active binary system HR 5110 in order to investigate coronal structures without such ambiguity. An 80 ks Chandra observation will constrain thermal coronal volumes through electron densities; radio observations will constrain nonthermal coronal volumes directly, and allow an estimation of the relative importance of thermal and nonthermal plasma in controlling and structuring active stellar coronae.

Proposal Number: 09200659

Title: Catching the Post-Outburst State of the Erupting Star V1118 Ori

PI Name: Marc Audard

Type: GO

We propose to catch the post-outburst state of the young accreting star V1118 Ori with Chandra and Spitzer. V1118 Ori underwent an optical outburst in January 2005 and has now returned to a ``quiescent'' state. Our X-ray monitoring observations have shown that the X-ray spectrum softened after the outburst, maybe due to changes in the magnetic structure near the star as a result of the increased accretion load. Our long-term monitoring indicates that the X-ray flux correlates with the optical flux, a signature that accretion can impact the X-ray emission of outbursting young stars. We propose also to obtain the post-outburst spectral energy distribution in the mid-infrared with Spitzer. We will compare the new data with those taken by us in the early phase of the outburst.

Proposal Number: 09200673

Title: Can different elements move with different velocities in a radiatively driven stellar wind?

PI Name: Lidia Oskinova

Type: GO

B-type stars of lower luminosity classes have relatively weak stellar winds. In this respect they resemble presumably the more massive, but metal-poor stars in the early Universe. Theory predicts that very thin stellar winds are multi-component fluids. The ions of iron group metals are accelerated by radiation pressure, but do not transfer their momentum to the bulk of material. This dynamical decoupling is not yet observationally confirmed. LETG HRC-S spectra of the X-ray brightest non-degenerate massive star alpha Cru will allow to detect different velocities of particle species in stellar wind. These observations will empirically confirm or disprove the effect of dynamical decoupling in a thin stellar wind.

Proposal Number: 09200690

Title: The Evolution of X-ray Emission in the Planet-Forming Era

PI Name: Jon Miller

Type: GO

The 4-30 Myr age range is particularly important in the life of pre-main sequence stars. It is in this age range where disks dissipate, as evidenced by a decrease in infrared excess emission arising from disks. Giant planets are expected to form in this age range, and the possible link between planet formation and disk dissipation is presently one of the most studied topics in star and planet formation. The dissipation of disks must have profound and testable consequences for the X-ray emission in this age range. Yet we are still lacking information on the early evolution of the X-ray emission in pre-main sequence stars. We therefore propose to make ACIS-I observations of fields in four 4-10 Myr clusters: NGC 7160, Tr 37, 25 Ori, and Ori OB1b.

Proposal Number: 09200730

Title: X-ray Emission from a 7 Myr Old, Accreting Herbig Ae star and its Jet: MWC 480

PI Name: Carol Grady

Type: GO

We are requesting Chandra ACIS-S imagery of MWC 480, a 7 Myr old Herbig Ae star with an accretion rate of 1E-8 solar masses/yr, intermediate between younger, accreting stars and older stars with transitional disks. The proposed integration will allow us to better delineate the evolution of X-ray activity in Herbig Ae stars, testing the hypothesis that the L_x is correlated with accretion signatures, rather than originating in coronal emission associated with a decaying dynamo. MWC 480 is also associated with a parsec-scale bipolar outflow, HH 728, with a 50" long counterjet which terminates in large, bright Herbig-Haro (HH) knot which will permit us to test models for X-ray production in HH knots over a wider range in outflow parameters than has been done to date.

Proposal Number: 09200763

Title: X-RAY AND UV PHOTOIONIZATION AND PHOTOEXCITATION OF PRE-MAIN-SEQUENCE STAR TRANSITIONAL DISKS

PI Name: Alexander Brown

Type: GO

Transitional disks are one of the most crucial and important stages of the evolution of pre-main-sequence stars and protoplanetary systems. These disks have transformed most of the dust and gas in their inner regions into planetesimals and show clear inner ``holes'' that almost certainly harbor infant planetary systems. We propose to observe 3 young stars with transitional disks (T Cha, GM Aur, LkHa 330) using ACIS-S to measure their X-ray radiation field and coronal emission properties and HST ACS-SBC to image the fluorescently excited molecular hydrogen in these systems to determine if the gas distribution follows the behavior seen in the dust distribution. Our broader goal is to model the X-ray/UV photoionization and photoexcitation of the disks and study their photochemistry.

Proposal Number: 09200803

Title: A detailed investigation of coronal/magnetic and rotational changes in cool stars using NGC 3532

PI Name: Steven Saar

Type: GO

We propose to use Chandra ACIS-I to study the one-to-one correspondence recently proposed between coronal/dynamo and rotational changes in cool stars. The goal is insight into the physical basis underlying the 3-part X-ray classification of cool stars (saturated, super-saturated, and normal rotation-activity), crucial to fully interpreting the rotational/magnetic/activity evolution of cool stars. We already have copious optical data on our rich target open cluster NGC 3532, including 83 rotation periods for the cluster members, making it uniquely useful for rotation-activity studies. Furthermore, its age, 300Myr, nicely bridges a gap in the age sequence of the best studied clusters between 100Myr (Pleiades) and 600Myr (Hyades), permitting detailed study of evolution between these epochs.

Proposal Number: 09200839

Title: X-ray Emission from the Hot White Dwarf KPD 0005+5106: Corona or Accretion?

PI Name: You-Hua Chu

Type: GO

X-rays at energies >0.5 keV, not expected from the photosphere of a white dwarf (WD), can be produced only in stellar coronae or from accretion of material onto a WD's surface. KPD 0005+5106 and WD 2226-210 are two outstanding cases of single WDs with X-ray emission at 1 keV. Recent Spitzer observations of WD 2226-210, the central star of the Helix Nebula, reveal excess continuum emission starting at 8 um and peaking at 24-70 um, indicating the existence of a dust disk at 50-100 AU from the star. The dust is most likely produced by collisions among Kuiper Belt-like objects (KBOs). Stray KBOs impacting the WD surface may produce the 1 keV emission. We request Chandra and Spitzer observations of KPD 0005+5106 to search for a similar dust disk and determine the origin of its 1 keV emission.

Proposal Number: 09200905

Title: Evaluating the Role of Photoevaporation in Protoplanetary Disk Dispersal

PI Name: Gregory Herczeg

Type: GO

Emission produced by accretion onto the central star leads to photoevaporation, which may play a fundamental role in disk dispersal. Models of disk photoevaporation by the central star are challenged by two potential problems: the emission produced by accretion will be substantially weaker for low-mass stars, and photoevaporation must continue as accretion slows. We propose use HST/ACS SBC PR130L to obtain FUV spectra of WTTSs and of CTTSs at low masses and mass accretion rates to provide crucial data to evaluate photoevaporation models. We will estimate the FUV and EUV luminosities of low-mass CTTSs with small mass accretion rates, CTTSs with transition disks and slowed accretion, and of magnetically-active WTTSs.

Proposal Number: 09200907

Title: A Hard Look at Stellar Disks at the Epoch of Planet Formation

PI Name: Lee Hartmann

Type: GO

We propose to use the HST/ACS/SBC and Chandra/ACIS-S3 to observe the high energy fluxes of 4 stars surrounded by disks in the newly discovered aggregate 25 Ori, the most populous 10 Myr group known within 500 pc. Our observations will cover the 1-25 A and 1250-2000 A bandpasses, and will complement our optical and Spitzer data for these objects, to provide essential input to physically-consistent models of disk structure and chemistry in the age range around 10 Myr, thought to be a critical period in the planet-forming process. Our proposed observations will double the number of 10 Myr old accreting stars with known high energy radiation fields, and will be the first FUV observations of low mass accreting stars in an OB association.

Proposal Number: 09200909

Title: Probing the Gas in the Planet Forming Regions of Protoplanetary Disks

PI Name: Nuria Calvet

Type: GO

The origin of planets is intricately tied to the evolution of primeval disks. The finer details of how the disk material evolves from an initially well-mixed distribution of gas and dust to a system composed mostly of large solids and gas giants like our own solar system is not well understood and is a fundamental question in astronomy. We can refine theories of planet formation and develop timescales for the evolution of planetary systems by studying the inner, planet-forming regions of protoplanetary disks.

Proposal Number: 09300001

Title: Resolving short supersoft source states of optical novae in the core of M31

PI Name: Wolfgang Pietsch

Type: GO

We propose to monitor the M31 core with five 23ks XMM-Newton EPIC and five 20ks Chandra HRC-I observations equally distributed from Nov 2007 to mid Feb 2008 to determine the light curves for short supersoft source (SSS) states of optical novae. SSS states with <100 d duration indicate accreting massive white dwarfs. They are proposed as SN Ia progenitors and determining their frequency is very important. We will correlate detected sources with novae from optical monitoring of the same area. With a nova rate in the field of ~25/yr and SSS states lasting from weeks to years we will follow light curves of many novae. Durations of the nova SSS state will allow us to constrain envelope and white dwarf masses. We will also monitor time variability of ~200 M31 centre X-ray sources (mostly XRBs).

Proposal Number: 09300101

Title: A Chandra Legacy Survey of Dynamically Active Globular Clusters

PI Name: David Pooley

Type: LP

From our experience with Chandra, we have determined an empirical, successful, and model-independent method for determining the the neutron-star low-mass X-ray binary (LMXB) content and bright cataclysmic variable (CV) of a globular cluster (GC) in a reasonably short ACIS exposure. We propose a program that will discover ~30 LMXBs and ~150 CVs in 31 GCs. When combined with other observations, we will have direct knowledge of over 90% of the total LMXB population in GCs. We will accurately determine the role of GC dynamics in the formation of both LMXBs and CVs. We will also obtain an estimate for the density of the LMXBs and CVs in the field. This study will have important implications both for theories of LMXB and CV formation and for theories of GC dynamics and evolution.

Proposal Number: 09300413

Title: The Symbiotic Star SS73 17: What Generates the Hard X-rays?

PI Name: Randall Smith

Type: GO

SS73 17 was an innocuous Mira-type symbiotic star until INTEGRAL and Swift discovered its bright hard X-ray emission. Suzaku observations then showed it emits three bright iron lines as well, with almost no emission in the 0.5-2 keV bandpass. The origin of the lines is unclear - scattered, thermal or photoionized sources, at high- or low-density are all plausible - but with a 100 ksec HETG observation we can resolve this question. Beyond its intrinsic interest as one of the few symbiotics showing hard X-rays (uniquely, it shows no optical flaring), SS73 17 may be the "missing link" that explains the line emission from the Galactic Ridge X-ray Emission (GRXE), as its iron lines have roughly the same radio as the GRXE while its soft X-ray flux is at or below ROSAT's detection threshold.

Proposal Number: 09300509

Title: Multiwavelength Observations of Two Bright Dust Forming CO Novae: V2362 Cyg and V1280 Sco

PI Name: Sumner Starrfield

Type: TOO

We request two 25 ks HRC-S+LETG observations for each of two slow, dust-forming, carbon-oxygen Classical Novae: V2362 Cyg and V1280 Sco. This will be the first time that this class of novae has been observed in X-rays. This is a Target-of-Opportunity proposal and we will use SWIFT to confirm that each nova is sufficiently bright for a grating spectrum before triggering our Chandra observations. Since the XRT instrument on SWIFT has roughly the same spectral resolution and effective area as ACIS-S on Chandra, the improved spectral resolution of the Chandra gratings is the justification for our observations. We will obtain monitoring observations with SWIFT, with Spitzer, Gemini, and other ground based telescopes.

Proposal Number: 09300602

Title: X-ray Jets Activity in the Symbiotic System CH Cyg

PI Name: Margarita Karovska

Type: GO

We propose follow up Chandra observations of the recently discovered X-ray jets in the nearby symbiotic system CH Cyg. CH Cyg is only the second symbiotic systems with jet activity detected at X-ray wavelengths. Symbiotic systems are fascinating accreting binaries with a key evolutionary importance since they are potential progenitors of bipolar PN and SN type Ia. The Chandra observations, combined with HST and VLA imaging, will provide the closest view of the region where jets form and interact with the surrounding material. The observations will provide a key information on the spatial, spectral and temporal characteristics of the jets, crucial inputs and quantitative constraints to models of non-relativistic jets.

Proposal Number: 09300685

Title: The Nature of the Soft Component in the Symbiotic Star, CH Cygni

PI Name: Koji Mukai

Type: TOO

The symbiotic star CH Cyg consists of an M giant and a white dwarf, and displays a two-component X-ray spectrum. The absorbed hard X-ray component is likely due to accretion onto the white dwarf. The unabsorbed soft X-ray component is thought to be either due to colliding winds or due to photoionization of the M giant wind by the hard component. We propose to obtain a high signal-to-noise grating spectrum of CH Cyg to resolve the origin of its soft component. Once we know its origin, we can begin to probe the environment around the white dwarf using the detailed spectral shape of the soft component. We propose this as a slow TOO, to be triggered when we know that CH Cyg is X-ray bright.

Proposal Number: 09400002

Title: Joint XMM-Newton/Chandra/RXTE Observations of Dips in Cyg X-1

PI Name: Joern Wilms

Type: GO

At phase 0, Cyg X-1 shows pronounced soft X-ray dips due to highly variable, partial blockage from the accretion stream. Studying these dips requires joint XMM/Chandra/RXTE observations: XMM will provide the continuum through the broad Fe line region (allowing a clean separation of the line into narrow and relativistically broadened components), and it will achieve higher S/N than Chandra at < 2keV, allowing the dipping events to be temporally resolved and spectrally modeled on short time scales. (RGS will have better spectral resolution than HETGS when both are binned to equal S/N on short time scales.) The Chandra data will provide high resolution spectroscopy of the dipping events, while RXTE - available via our ongoing monitoring campaign - will provide the hard X-ray continuum.

Proposal Number: 09400003

Title: Monitoring Observations of the Galactic Center Region

PI Name: Rudy Wijnands

Type: GO

We propose to continue our XMM-Newton and Chandra monitoring campaign of the inner 1.2 square degree region centered on Sgr A*. We will be able to detect very faint transients in this region with a peak luminosity of 1E33 - 1E35 ergs/s, 10-1000 times more sensitive than would be possible with other satellites (i.e., RXTE and INTEGRAL}. This allows us to observe a very poorly studied group of transients and to follow the luminosity behavior of faint (1E36 ergs/s) persistent sources.

Proposal Number: 09400014

Title: Chandra follow-up of a weak persistent source found in INTEGRAL maps: IGR J17204-3554

PI Name: Mariano Mendez

Type: GTO/ALTERNATE

We propose to observe IGR J17204-3554 for 1 ksec exposure with the ACIS-I to obtain a sub-arcsec position of the X-ray source in combination with spectral characteristics. The unique Chandra positional capabilities will allow for an optical follow-up study, which is of paramount importance for the classification of the source.

Proposal Number: 09400018

Title: Chandra follow-up of weak persistent sources found in INTEGRAL maps

PI Name: Mariano Mendez

Type: GTO/TOO

We propose to obtain a 1 ksec exposure of up to 2 newly found unclassified INTEGRAL sources which are weak persistent X-ray sources (we exclude from this proposal the bright new transients discovered by INTEGRAL). The unique Chandra positional capabilities will allow for an optical follow-up study. Follow-up observations are of paramount importance for the classification of the sources (e.g. as HMXBs/LMXBs, pulsars and pulsar wind nebula, or in a few rare cases as AXP/SGR or INS).

Proposal Number: 09400019

Title: Chandra follow-up of a weak persistent source found in INTEGRAL maps

PI Name: Mariano Mendez

Type: GTO

We propose to observe XTE J1716-389 for 1 ksec exposure with the ACIS-I to obtain a sub-arcsec position of the X-ray source in combination with its X-ray spectral characteristics. The unique Chandra positional capabilities will allow for an optical follow-up study, which is of paramount importance for the classification of the source.

Proposal Number: 09400020

Title: The Galactic Bulge Survey: categorising the plethora of faint X-ray sources in the Galactic Bulge

PI Name: Mariano Mendez

Type: GTO

We propose to image an area of 6x1 degrees centered on the Galactic Center at |b|=1.5 degrees. Here, we propose to obtain ~25% of this as part of SRON's GTO program. These regions have been selected because of their lower extinction and crowding in the optical and near-infrared than in the Galactic Center area, while still having a high density of X-ray sources. We will detect a plethora of faint X-ray sources that will constrain binary evolution models by way of a number count and by identifying predicted X-ray binary types that so far have eluded identification. Source identifications will be boosted by our obtained optical data. We expect to find (quiescent) eclipsing neutron star and black hole LMXBs. These are important for neutron star and black hole mass measurements.

Proposal Number: 09400055

Title: HETG Observations of the Accretion Disk Corona Source X1822-371

PI Name: Claude Canizares

Type: GTO

X1822-371 is the prototype of the Accretion Disk Corona (ADC) sources, i.e., near edge-on low mass X-ray binaries where the primary emission is observed via scattering in a very spatially extended corona, and we are viewing the X-ray source partially eclipsed/absorbed by the atmosphere of the outer accretion disk. We therefore propose Chandra High Energy Transmission Gratings (HETG) observations to obtain line diagnostics of the disk atmosphere and structure. Our observations are designed to go substantially deeper than the existing archive observation, i.e., doubling the signal-to-noise, and thus providing a "legacy" dataset for HETG observations of ADC.

Proposal Number: 09400117

Title: Transient LMXBs in Globular Clusters: More Numerous Than We Thought?

PI Name: David Pooley

Type: TOO

Since the discovery of globular cluster LMXBs in the 1970s, it was assumed that there was only one bright LMXB per cluster. Deep Chandra observations of several globular clusters have revealed that they contain numerous quiescent LMXB systems, any of which could go into outburst. Our observations will determine whether new outbursts from transient LMXBs in NGC 6440, Terzan 5, and Terzan 1 are from the same sources that were previously seen in outburst.

Proposal Number: 09400125

Title: X-Ray Jets in Microquasars

PI Name: Stephane Corbel

Type: TOO

We propose Target of Opportunity (ToO) observations for detailed studies of X-ray jets from microquasars. We describe our discovery of radio/X-ray jets in two microquasars, why X-ray jets are probably much more common than previously thought, and transient X-ray jets offer an exciting new way to probe the physics of relativistic jets from black holes. The proposed ToO observations are optimized to discover and study (flux evolution, morphology, SED, proper motion, ...) of new X-ray jets from microquasars, triggered by their detection as radio lobes. This will have implications not only for the study of jets from Galactic X-ray binaries, but also for our understanding of relativistic jets from active galactic nuclei (AGN).

Proposal Number: 09400192

Title: Crustal cooling in quiescent neutron stars

PI Name: Edward Cackett

Type: GO

We propose a 30 ksec observation of each of the quasi-persistent neutron-star low-mass X-ray transients KS 1731-260 and MXB 1659-29 in quiescence. The long outbursts in both of these sources heated the neutron star crust out of thermal equilibrium with the core. We have tracked the cooling of the neutron star crusts in both objects since they went in quiescence. We have preliminary evidence that the cooling has ceased, perhaps indicating that the crust is in equilibrium with the core. Our proposed observations will test the equilibrium suggestion, by placing tight limits on residual cooling and/or residual accretion, and determine the core temperature, constraining the equation of state of dense matter.

Proposal Number: 09400196

Title: The Galactic Bulge Survey: categorising the plethora of faint X-ray sources in the Galactic Bulge

PI Name: Peter Jonker

Type: GO

We propose to image an area of 6x1 degrees centered on the Galactic Center at |b|=1.5 degrees: the Galactic Bulge Survey. 25% of this area will be observed as an SRON GTO program in AO9. We here propose for another 25%. These regions have been selected because of their lower extinction and crowding in the optical and near-infrared than in the Galactic Center area, while still having a high density of X-ray sources. We will detect a plethora of faint X-ray sources that will constrain binary evolution models by way of a number count and by identifying predicted X-ray binary types that so far have eluded identification. We expect to find (quiescent) eclipsing neutron star and black hole LMXBs. These are important for neutron star and black hole mass measurements.

Proposal Number: 09400208

Title: Following a black hole candidate X-ray transient to quiescence

PI Name: Peter Jonker

Type: TOO

There is increasing evidence that the quiescent state of BH X-ray binaries is different from the hard state that is observed at higher luminosities. Our recent Chandra campaigns on BH transient decays suggest that a transition takes place when the luminosity suddenly drops by almost three orders of magnitude during a period of only a few weeks. This transition has so far not been resolved, but there is strong evidence that the spectrum softens during this rapid decay. Both the decay and spectral evolution can provide important constraints for jet-dominated and ADAF-like models. We propose a more refined program than before and request 6 simultaneous Chandra/VLA TOO observations that aim to cover this rapid transition in full detail for the first time with X-ray and radio observations.

Proposal Number: 09400224

Title: High Resolution Spectroscopy of GRS 1915+105 in the 'Soft' State

PI Name: Yoshihiro Ueda

Type: TOO

We propose to perform a TOO observation of GRS 1915+105 in the soft state with Chandra/HETGS. Investigation of iron-K absorption lines provide us with powerful diagnostics of highly ionized plasma associated with the accretion flow of microquasars. Although such features were discovered firstly from superluminal sources, the nature of the highly ionized plasma in GRS 1915+105 and its possible relation to relativistic jet ejection still remains unclear. This is because the source stays mostly in the low/hard state, where the ions are fully ionized by the strong hard X-ray flux and a very weak feature from H-like Fe ions is observable. Previous ASCA observations indicate that the iron-K absorption features become prominent in this state, thus best suited for detailed plasma diagnostics.

Proposal Number: 09400231

Title: ToO observation of a new bright transient discovered by GLAST and Swift in the Galactic plane

PI Name: Isabelle Grenier

Type: TOO

We propose a TOO observation of a new intense transient detected by GLAST-LAT and followed by a Swift-XRT detection, at |b|<5 deg. Our goal is to determine the nature of an event similar to the intense, non-blazar, transient that EGRET saw in the Galactic plane once in its lifetime. The lack of a radio-loud source and of a known X-ray binary in the error box indicates either a new facet of Galactic compact objects or a new manifestation of a non-blazar active galaxy behind the Milky way. A significant XRT detection of a counterpart will trigger the proposed 30 ks Chandra observation to precisely locate the source in crowded Galactic regions, to constrain the X-ray decay time, and to measure the source spectrum and absorption.

Proposal Number: 09400314

Title: Photoionization in the Microquasar Circinus X-1

PI Name: Norbert Schulz

Type: GO

We propose to reobserve the X-ray binary Circinus X-1 for a total of 35 ks within an orbital phase window of 0.96 - 0.99 within its 16.5 day orbital cycle using the HETGS. Circinus~X-1 is currently in a low flux state with respect to its longterm (30 yr) lightcurve. A short previous observation of the source at this phase revealed a remarkable emission line spectrum rich in high Z K-shell lines from Si, S, Ar, Ca, and Fe. While the overall spectrum was successfully modeled using the most recent version of the photoionization code XSTAR, we encountered problems in the modeling of specific lines which to a large extent are related to the short exposure and shortcomings in the instrumental setup.

Proposal Number: 09400351

Title: Crust cooling of HETE J1900.1-2455 and Swift J1626.6-5156

PI Name: Nathalie Degenaar

Type: TOO

We propose Chandra ToO observations of the two neutron star quasi-persistent X-ray binaries HETE J1900.1-2455 and Swift J1626.6-5156 in quiescence. Currently, both sources exhibit an outburst phase that started about 1.5 years ago. Neutron stars that undergo such a prolonged accretion period serve perfectly to study their cooling behavior, which depends sensitively on stellar parameters such as composition and compactness. We want to explore the effect of a strong magnetic field on the thermal evolution of transiently accreting neutron stars. Cooling models for neutron stars with a low magnetic field currently exist, and also magnetars are well studied. Our selected targets fall right in between this regime and can provide new physical input in the existing theory of cooling neutron stars.

Proposal Number: 09400355

Title: Quasi-persistent neutron-star X-ray binaries in quiescence

PI Name: Rudy Wijnands

Type: TOO

We propose to observe the next (quasi-)persistent neutron-star low-mass X-ray binary that turns off and becomes quiescent. This will provide an excellent opportunity to study the effects of prolonged accretion on the neutron-star properties (i.e., crust and core and thus the properties of ultradense matter) and the quiescent properties of low-mass X-ray binaries. Two follow-up observations taken several months later will provide important information about the time evolution of the quiescent properties. In particular, if indeed the quiescent X-rays are emitted by the crust, we will be able to study its evolution in time,thus setting strong constraints on the crust cooling models and the exact structure of the crust.

Proposal Number: 09400380

Title: First Chandra observation of the ultra-compact X-ray binary 4U~1850--087 during its high luminosity state

PI Name: DIEGO ALTAMIRANO

Type: TOO

4U~1850--087 is a candidate ultra-compact X-ray binary. A soft excess near 0.7 keV has been reported for this source with ASCA and interpreted as due to neutral Ne-rich material local to the binary. Recent XMM-Newton and Chandra observations of the source at low X-ray luminosity do not confirm the ASCA results and therefore different physical interpretations are possible. We propose at 30 ks Chandra LETGS observation of this source during its high luminosity state in order to understand how the luminosity affects the abundances observed in the X-ray spectrum.

Proposal Number: 09400397

Title: Monitoring observations of the Galactic Center region

PI Name: Rudy Wijnands

Type: GO

We propose to continue our Chandra and XMM-Newton monitoring campaign of the 1.2 square degree region centered on Sgr A*. We will be able to detect very faint transients with a peak luminosity of 1E33-1E35 ergs/s, 10-1000 times more sensitive than would be possible with other satellites. This allows us to observe a poorly studied group of transients and to follow the luminosity behavior of faint (1E34-1E36 ergs/s) persistent sources. The Chandra observations are necessary to facilitate rapid follow-up observations of the detected transients at IR and radio wavelengths; the XMM-Newton observations are needed to increase the likelihood of detecting transients in outburst and to obtain better constraints on the long-term time averaged accretion rates of the transients present in the FOV.

Proposal Number: 09400409

Title: Faint persistent X-ray sources in the Galactic Bulge

PI Name: Marc Klein-Wolt

Type: GO

We propose short (1 ksec) observations with the HRC-I of a selection of faint persistent X-ray sources in the Galactic Bulge for which very little is know. These sources are detected in the PCA/RXTE bulge scan project at luminosities below 10^36 erg/sec and are most likely HMXB or LMXB; they are either Be/X-ray binaries, and hence candidates to show slow X-ray pulsations, or they are ultra-compact binaries in which the compact object is accreting from a degenarate donor and in which case they are candidates to show gravitational waves. The HRC observations will allow us to search for slow pulsations as well give for the first time an accurate position that will allow for optical/IR follow-up studies to determine the binary parameters.

Proposal Number: 09400414

Title: INVESTIGATING NEW INTEGRAL SOURCES WITH CHANDRA

PI Name: Adamantia Paizis

Type: TOO

We propose to trigger a maximum of 2 Chandra medium (4-12 days) ToO observations on new sources discovered by the INTEGRAL Observatory. We ask for 20 ksec per observation, using HETGS. The scientific aim is to determine the source position with subarcsecond accuracy that only Chandra can provide, enabling multiwavelength follow-up observations (coordinated within the proposing team), and to obtain the high resolution HETG X-Ray spectrum, essential to determine the nature of the new source. With this proposal we aim to continue the successful INTEGRAL-Chandra monitoring program started since Chandra AO5.

Proposal Number: 09400441

Title: Chandra observations of an engimatic class of faint accreting slow pulsators

PI Name: Rudy Wijnands

Type: GO

We propose a series of 1 ksec Chandra observations of an enigmatic class of objects: faint to very faint accreting slow pulsators with period greater than several hundreds of seconds. The nature of these objects is unclear; likely they are neutron stars accreting from a high-mass companion star, but often an accreting magnetized white dwarf nature (i.e., an intermediate polar) cannot be excluded. With our proposed Chandra observations we will obtain a position of these sources which will be used to identify their optical/IR counterpart, crucial in determining the exact nature of these systems. In addition, we request short (5 ksec) XMM-Newton observations of the same targets which will result in good spectra and allow for searches to be undertaken for any spin-period derivatives.

Proposal Number: 09400498

Title: TOO observation of the microquasar GRS 1915+105 in quiescence

PI Name: Paolo Soleri

Type: TOO

We propose a 40ks Chandra observation to detect the microquasar GRS 1915+105 in quiescence, should its current 15-year-long outburst end during the 9th Chandra observing cycle. This system has never been observed in quiescence: its properties suggest that its quiescent X-ray flux would be rather high, allowing a measurement of the spectrum and a test of models for quiescent emission in black-hole binaries. In addition, it will be possible to detect a fossil jet similar to that detected in the neutron star X-ray binary 4U 1755-33.

Proposal Number: 09400544

Title: Precise Localization of Neutron Star Soft X-ray Transients

PI Name: Deepto Chakrabarty

Type: TOO

We propose to observe four neutron star (NS) soft X-ray transients in outburst to obtain accurate source positions, continuing an ongoing successful program we initiated in Cycle 6. This continuing study will allow for the reobservation of such sources in future cycles to study the quiescent X-ray emission in NS SXTs. Recent results from Chandra and XMM suggest that the standard picture of NS SXT emission may not be as straightforward as previously thought. This proposal will increase the number of known SXTs with good positions, providing a more uniform sample of the population for future work.

Proposal Number: 09400550

Title: High Resolution Spectroscopy of a Black Hole Transient

PI Name: Jon Miller

Type: TOO

We propose to continue our ongoing study of Galactic black hole transients in outburst in a streamlined form, via two (2) 30 ksec HETGS observations. This program has revealed relativistic Fe K disk lines, warm-absorber-like disk winds, and now a possible anti-correlation between winds and jets. Observations of a new transient outburst will permit a black hole spin constraint, and test connections between disks, winds, and jets as a function of accretion rate. We will support this program with a global multi-wavelength network of observatories.

Proposal Number: 09400622

Title: The Nature of the Intermediate-Luminosity X-ray Sources in Globular Clusters

PI Name: Craig Heinke

Type: GO

We propose short observations of four globular clusters seen to contain relatively bright (L_X[0.5-7 keV]=5x10^33 to 10^35 ergs/s) low-luminosity X-ray sources by Einstein, ROSAT and/or Chandra HRC observations. These objects are either extremely bright cataclysmic variables in unusual accretion states, or quiescent low-mass X-ray binaries showing very low-level accretion activity. With 5 to 10-ksec snapshots, we will constrain the luminosities, spectra, positions, and nature of each object.

Proposal Number: 09400640

Title: Observations during the rare dips observed on the X-ray binary SLX 1735--269

PI Name: DIEGO ALTAMIRANO

Type: TOO

SLX~1735--269 is a (candidate) ultra-compact X-ray binary. It is a persistent source which shows rare dips that cannot be explain as periodic obscuration by material located in a thickened outer region of the accretion disk due to its interaction with the inflowing gas stream from the companion. We propose to observe this source for 10~ksec during one of its dips in order to understand if the accretion on the compact object ceases, or remains at very low levels undetectable with RXTE. The observations will also allow us to estimate the temperature of the neutron star crust.

Proposal Number: 09400681

Title: Understanding the nature of high inclination low mass X-ray binaries: broad-band and line spectra from A1744-361

PI Name: Tod Strohmayer

Type: TOO

We propose to observe the transient dipping LMXB system A1744-361 during an outburst with Chandra HETGS, and contemporaneously with RXTE PCA. This will be the first observation of A1744-361 with a high resolution spectral instrument, and will facilitate; (1) sigficant detection of narrow spectral lines for the first time from A1744-361, (2) detection and line profile measurement of its broad iron emisson line, (3) unambiguous determination of source orbital period, (4) unambiguous determination of source position, (5) sigficant detection of kHz QPOs, and (6) understanding of the ionized plasma in the immediate environs of A1744-361, and dippers in general. These science goals rely on the unique qualities of Chandra (e.g., high spectral and angular resolution) and RXTE.

Proposal Number: 09400783

Title: From Super-Eddington to zero: following a Z source into quiescence

PI Name: Jeroen Homan

Type: TOO

XTE J1701-462 is probably the most luminous Galactic transient neutron star LMXB (NSXB) in the history of X-ray astronomy. Early observations have already clarified our view on the role of mass accretion rate in NSXBs. Observing XTE J1701-462 as it returns to quiescence will create a unique opportunity to study the effects of mass-accretion rate on the spectral/variability properties in a single NSXB over an unprecedented luminosity range. We propose a Chandra/XMM-Newton TOO program with two goals: 1) observe the source during the end of the decay and in quiescence, to complete what might well become a 'Rosetta stone' for NSXBs and 2) constrain the structure of neutron stars by studying the effects of near-Eddington accretion on the cooling of the crust/core in transient NSXBs.

Proposal Number: 09400813

Title: Localization and Spectra of INTEGRAL-Selected Sources in the Galactic Plane

PI Name: John Tomsick

Type: GO

The INTEGRAL satellite is discovering a large number of new hard X-ray sources in the Galactic plane. In most cases, the few arcminute INTEGRAL positions do not allow for identification of these IGR sources at other wavelengths, leaving their nature unclear. Chandra can make a major contribution to studies of IGR sources by localizing the sources to allow for the identification of multi-wavelength counterparts and by constraining their soft X-ray spectra. Many of the IGR sources that have been identified are High-Mass X-ray Binaries (HMXBs) with interesting properties. We propose for relatively short Chandra observations of 24 unidentified IGR sources in the Galactic plane to search for HMXBs or other unusual Galactic sources.

Proposal Number: 09400831

Title: Spectroscopy of a bright burst from 4U 1812-12

PI Name: Johannes in 't Zand

Type: TOO

Our goal is to measure with the HETGS a bright type-I X-ray burst with photospheric radius expansion (PRE), search for signatures of the ashes of nuclear burning and, if succesful, attempt a measurement of the gravitational redshift. The target, 4U 1812-12, is an ultracompact X-ray binary whose bursts are known to be consistently very bright, show strong PRE and are fairly predictable in occurrence. We request a joint RXTE observation to measure the neutron star spin via burst oscillations.

Proposal Number: 09400910

Title: Spitzer-Chandra ToO Observations of a Short Duration GRB

PI Name: Kevin Hurley

Type: TOO

We propose an ambitious multiwavelenth approach to the short GRB problem, leveraging Spitzer with Chandra as well as numerous ground−based telescopes. By measuring the broad−band spectrum of the afterglow and any concurrent "mini−supernova" over a wide range of wavelengths at several epochs, we can distinguish between models proposed to explain this type of burst. We will constrain the energetics of the explosion and the short GRB bursting rate (an important number for gravitational wave observatories), and measure with unprecedented detail the stellar content of a short burst host galaxy. Given the high impact nature of these observations and the rarity of short bursts, we are requesting multiepoch Target of Opportunity observations on a single event in Cycle 4.

Proposal Number: 09500023

Title: Investigating possible magnetar-like outburst behaviour from high-B radio pulsars and XDINSs

PI Name: Mariano Mendez

Type: GTO/TOO

We propose a Chandra ACIS-S ToO observation of 10ks of any X-ray Dim Isolated Neutron Star (XDINS) and high magnetic field radio pulsar within 30 days from the detection of an increase (of an order of magnitude) of their soft X-ray, optical or radio flux. Radio and X-ray outbursts have been recently discovered from magnetars. This study is aimed at unveiling similarities between the high-B pulsar and XDINS classes with respect to the magnetar class, and consequently to understand their differences despite the common high magnetic fields (greater than the electron critical magnetic field). Through this Chandra observation we will study any timing and spectral variabilities connected with these outbursts.

Proposal Number: 09500026

Title: Galactic Supernova Remnant G272.2-3.2

PI Name: Gordon Garmire

Type: GTO

We propose to observe Galactic supernova remnant (SNR) G272.2-3.2. G272.2-3.2 is one of the SNRs discovered in X-rays, and has been suggested to a thermal composite SNR. However, the previous studies indicated that the properties of this SNR is extremely uncertain. The proposed Chandra observation will be useful to resolve many aspects of the uncertain nature of G272.2-3.2, including the origin of the SNR.

Proposal Number: 09500030

Title: Snap-shot survey of potential GeV and TeV pulsars

PI Name: Gordon Garmire

Type: GTO

We propose to observe a number of energetic, young, radio pulsars that has not yet been studied in X-rays. The pulsars and their wind nebulae are especially interesting since they are expected to be the GeV and TeV sources detectable in the near future with the Glast and HESS observatories. In the short, 10 ks, exposures we expect to detect emission from the pulsars and PWNe in all cases. Obtained images and spectra will allow us to select the brightest, most interesting objects for more detailed follow-up studies.

Proposal Number: 09500037

Title: High Resolution HRC Imaging of Supernova Remnant 1987A

PI Name: Stephen Murray

Type: GTO

ACIS observations of SN 1987A have provided unique images of an evolving young supernova remnant. However, because the ACIS pixels undersample the PSF, these data cannot be used to derive robust measurements and uncertainties for parameters such as the radius and thickness of the emitting shell, nor can they quantitatively differentiate between geometries such as a thick shell or a tilted ring. We consequently propose an HRC observation of SN 1987A. When combined with ACIS and radio data from nearby epochs, the HRC data will allow a high fidelity reconstruction of the underlying morphology. Note that these HRC data complement rather than conflict with any Cycle 9 ACIS observation of SN 1987A, since ACIS data carry spectral information, while HRC data have superior spatial resolution.

Proposal Number: 09500130

Title: The extreme late-time light curve of GRB 060729

PI Name: Dirk Grupe

Type: GO

Conflicting results from optical measurements on one hand and recent Swift X-ray observations on the other challenging the predictions from the standard 'fireball' model of Gamma-Ray Bursts (GRBs) that jet openning angles can be determined from the light curve's break times: While optical light curves suggest early break times and therefore small opening angles, the Swift XRT observations show no jet breaks in the majority of afterglow light curves, even weeks after the trigger. Here we propose to observe the bright X-ray afterglow of GRB 060729 twice with Chandra for 80 ks at the beginning and 120 ks at the end of the AO-9 to extend its light curve beyond any X-ray afterglow that has ever been observed, putting strong constrains on the opening angle and GRB theory.

Proposal Number: 09500172

Title: The 'black-widow' pulsar in X-rays

PI Name: Vyacheslav Zavlin

Type: GO

We propose a deep observation of the "black-widow" eclipsing millisecond pulsar B1957+20 in a 33-ks orbital period binary system with a low-mass companion. The system is the only currently known example where the interactions of the pulsar wind with the interstellar medium and the wind from the companion have been observed. This was accomplished by a previous Chandra observation that lasted 43 ksec. These interactions are tools for elucidating properties of the relativistic wind which carries away the pulsar's rotational energy. Our study will provide much more detail for the physical properties of both the termination and intrabinary shocks and, hence, further insight into the nature of pulsar winds.

Proposal Number: 09500216

Title: Chandra Observations of Young, Energetic Supernovae

PI Name: David Pooley

Type: GO

In the entire history of X-ray astronomy, only about three dozen core-collapse supernovae (SNe) have been detected at ages of days to years old. Of these, only a handful have been well-followed temporally. Few general trends have emerged, and there is a clear need for better X-ray coverage at ages of ~years. Two SN subclasses stand out as deserving of particular attention, namely, the type Ib/c SNe, which have been associated with long-duration gamma-ray bursts, and the type IIn SNe, which are very poorly understood but have the highest X-ray luminosities seen in SNe. We propose observations of a number of interesting SNe of these subclasses at ages of years.

Proposal Number: 09500239

Title: A Deep Chandra Observation of SMC SNR 0104-72.3

PI Name: Sangwook Park

Type: GO

We propose to observe the supernova remnant (SNR) 0104-72.3 in the Small Magellanic Cloud (SMC). SNR 0104-72.3 is relatively faint and the X-ray images show ~arcsec scale substructure. There is also an X-ray point source within the SNR boundary. Furthermore, the origin of 0104-72.3 has been controversial between Type Ia and II. X-ray characteristics of 0104-72.3 make a deep Chandra ACIS observation the unique tool for the study of this SNR. Our proposed 120 ks ACIS observation would be useful to reveal the origin of 0104-72.3.

Proposal Number: 09500297

Title: Timing PSR J1852+004 in Supernova Remnant Kes 79: Plan B

PI Name: Jules Halpern

Type: GO

Timing of PSR J1852+0040 in SNR Kes 79 has shown no change in its spin period. Its surface B is < 2x10^11 G in the dipole spin-down formalism, unique for a young, rotation-powered pulsar, and incompatible with its X-ray luminosity and pulse properties. Instead, it may be accreting supernova debris, in which case it can remain in a near-equilibrium spin with only random torque noise. We propose to continue our timing of PSR J1852+0040 to measure its P-dot and/or torque noise in order to decide between these models. In any model, PSR J1852+0040 must have a weak magnetic field, which may also explain the class of CCOs, e.g., 1E 1207.4-5209. In those pulsars born spinning slowly, the dynamo may generate a weaker field, which enables it to accrete.

Proposal Number: 09500337

Title: Chandra Observations of New X-ray Supernovae

PI Name: David Pooley

Type: TOO

We propose to continue our X-ray studies of Type II and Type Ib/c supernovae (SNe). The Swift satellite has ushered in a new era of studying SNe in the X-rays, obtaining densely sampled X-ray lightcurves for the first time. However, its spatial resolution is often not good enough to separate a SN from nearby sources. We propose short Chandra observations to alleviate this. These observations will assess the X-ray environment of newly discovered Swift SNe to determine any possible source confusion or contamination of the SN flux. Our strategy makes the best use of the capabilities of each observatory.

Proposal Number: 09500381

Title: Phase-resolved Imaging of Compact Structures in a Pulsar Bow Shock

PI Name: Chi-Yung Ng

Type: GO

G359.23-0.82 ("the Mouse") is the ideal system for studying the physics of pulsar bow shock nebulae. However, ACIS observations of the Mouse offer little insight into compact nebular structures close to the pulsar, because of both pile-up and the likely presence of significant X-ray emission from the pulsar itself. We here propose an HRC-I observation of the Mouse, phase-resolved imaging from which will provide high-fidelity data on nebular structures close to the pulsar. With these data, we can identify possible wisps, jets, knots or other structures near or within the Mouse's termination shock, allowing us to compare the properties of the relativistic flow and particle acceleration process under a bow shock geometry to those seen in the well-studied "Crab-like" nebulae.

Proposal Number: 09500446

Title: A Measurement of the Expansion Rate of SN 1006

PI Name: Robert Petre

Type: GO

We propose to make the first X-ray proper motion measurement of SN 1006, by taking an identical 70ks ACIS-S exposure of the bright NE rim to one taken 7 years ago. If X-ray expansion is comparable to radio, then the shock proper motion of 3000 km/s produces a shift of 7 ACIS pixels compared with the reference observation. Proper motion of thin (10 arcsec) nonthermal filaments and interior ejecta knots will be easily detected, as will brightness changes at the 10 percent level on 3-5 arcsec scales. Brightness changes in the nonthermal rims would arise from the influence of spatial variations in magnetic field strength on synchrotron loss timescales. SN 1006 is the best remnant in which to measure the proper motion of nonthermal shocks because it is nearby, bright, and has fast shocks.

Proposal Number: 09500471

Title: A Deep Chandra Observation of G54.1+0.3

PI Name: Patrick Slane

Type: LP

Chandra observations of pulsar wind nebulae have revolutionized our understanding of these systems, revealing a wide variety of complex structures that all relate to the basic conversion of spin-down power to an axisymmetric wind with collimated outflows. Based on initial observations, G54.1+0.3 displays Doppler-brightened emission from the wind termination shock region, large-scale jets that form the elongated structure of the nebula, and faint emission that hints at a possible torus as well as large-scale filamentary structure. We propose a Chandra Large Project to obtain deep observations of G54.1+0.3 in order to resolve these structures, study their spectra, and derive properties related to flow conditions and the magnetic field structure of the nebula.

Proposal Number: 09500479

Title: The X-ray Afterglow of a Gamma-ray Burst detected and localized with the AGILE gamma- and X-ray detectors

PI Name: Marco Feroci

Type: TOO

AGILE will be the first mission to observe GRBs in the range ≥ 30 MeV after the afterglow revolution, allowing the high energy emission to be studied for the first time in the frame of information derived from the afterglow, such as distance, host, decay law, .. We propose a 60 ks ToO observation of one AGILE GRB, observed in gamma-rays and arcmin localized at X-rays by SuperAGILE. The main scientific objectives are the arcsec localization of the X-ray counterpart, allowing for the first time ever an association of a gamma-ray emitting GRB with counterparts at other wavelengths (thus possibly with a redshift and a host galaxy), and the study of the X-ray afterglow, correlated to the observable prompt and/or delayed emission in the 30 MeV 50 GeV range.

Proposal Number: 09500556

Title: Determining the nature of the quasi-pointlike TeV source HESS J1858+020

PI Name: R gis Terrier

Type: GO

Most HESS sources are very extended objects for which counterparts are difficult to find. But all point like or quasi point like objects have rich X-ray counterparts. In particular, HESS J1813-178 has revealed a bright X-ray nebula enclosed in a radio shell. Recent Chandra observations have resolved a very energetic pulsar candidate in this nebula. We propose to observe the newly discovered quasi point like source HESS J1858+020, which is devoid of any X-ray observations. Its TeV spectral characteristics are very similar to those of HESS J1813-178, reminding a possible young pulsar wind nebula. We propose to test this hypothesis using a 30 ks ACIS-I pointing which should be able to reveal a pulsar wind nebula or on the contrary a possible compact source origin of the emission.

Proposal Number: 09500565

Title: Investigating the X-ray Variability of Cassiopeia A

PI Name: Daniel Patnaude

Type: GO

We propose a 50 ksec ACIS-S observation of Cas A to follow X-ray flux changes associated with ejecta recently encountered by the reverse shock. This will allow us to investigate Cas A's near-term X-ray evolution and the fine-scale structure of its SN debris. We also request the Chandra observation be followed by HST NICMOS & WFPC2 images of four identified X-ray variable features in the high ionization NIR lines of [Si VI] and [Si X] and low ionization optical lines of [S II] and [O III]. The proposed X-ray/optical/NIR observations will yield a multi-wavelength study of the remnant's advancing reverse shock in an inhomogeneous multi-phase ejecta medium at resolutions down to a fraction of an arcsecond, providing a hi-resolution broad temperature study of reverse shock heated SN ejecta.

Proposal Number: 09500572

Title: Completing a Small Chandra Survey of Hard X-ray Sources in Gamma-Ray Error Boxes

PI Name: Mallory Roberts

Type: GO

Recent X-ray and radio studies of unidentified high-energy gamma-ray source error boxes (detected by EGRET) have yielded numerous likely counterparts. These have been young pulsars coincident with steady EGRET sources, rapidly moving pulsar wind nebulae coincident with variable EGRET sources, radio emitting Be X-ray binaries, background blazars, and associations of massive stars. We propose brief observations of the final 3 hard X-ray sources discovered in an ASCA survey of Galactic GeV source error boxes to determine if any are members of the above source classes or can be identified with other potential gamma-ray emitters. The precise positions from these observations may be important for successful blind searches for pulsations in data from GLAST.

Proposal Number: 09500577

Title: A Search for X-ray Pulsations from Rotation-Powered Millisecond Pulsars

PI Name: Kent Wood

Type: GO

We propose HRC-S observations of 8 rotation-powered millisecond pulsars (RMSPs) to search for pulsations and measure fluxes. We show it is not possible to identify a single figure of merit that explains current detection patterns and prioritizes new searches. A blend of two figures of merit (successful with X-ray hard and thermal subclasses respectively) maximizes prospects for new detections. This survey will clarify the roles of X-ray and gamma-ray emission from RMSPs, and prepares for GeV observations with GLAST. The number of known X-ray RMSPs of the hard subclass could be doubled. Enlarging source counts is essential to understanding the characteristics of RMSPs seen in radio, X-rays, and gamma-rays.

Proposal Number: 09500603

Title: Shock Interactions in the Supernova Remnant IC443

PI Name: Una Hwang

Type: GO

We propose two ACIS-I observations to obtain high-quality spectra and images of the bright northeast region of the supernova IC 443. We aim to identify coherent shock structures in conjunction with optical images, and to perform spatially resolved spectroscopy and spectral imaging. The northeast region of IC 443 is interacting with diffuse interstellar medium, atomic and molecular clouds at its various boundaries. We will explore compare the X-ray ane optical morphologies in detail, and measure the temperature and density structures of the X-ray emitting gas behind these different shock environments. We will also search for correlations with coronal [Fe X] and [Fe XIV] emission to look for signatures of cloud evaporation.

Proposal Number: 09500615

Title: The Peculiar X-Ray Evolution of Supernovae 1978K, 1979C and 1993J

PI Name: Stefan Immler

Type: GO

Supernovae (SNe) 1978K, 1979C, and 1993J are some of the brightest and best observed SNe in the X-ray regime. Over the past ~2 decades, SNe 1978K and 1979C have shown no evolution in X-rays, with high sustained (0.2-10 keV) luminosities around E39 ergs/s and high inferred mass-loss rates of the progenitors (>E-4 M_sun/year) over the last 40,000 years prior to their explosions. However, the latest Chandra, XMM-Newton and Swift observations show a dramatic decrease in their X-ray luminosities similar to that of SN 1993J. We propose Chandra observations to follow their fast rates of decline which will bring the long-term X-ray monitoring of these three SNe to a final closure.

Proposal Number: 09500627

Title: ToO Observations of Soft Gamma Repeaters

PI Name: Peter Woods

Type: TOO

Soft Gamma Repeaters are rare sources of transient burst emission, probably magnetars (i.e. strongly magnetized neutron stars). Each of the SGRs has a persistent X-ray counterpart and some show coherent pulsations. During burst active phases, these counterparts undergo changes in their energy spectrum and pulse properties. Measuring the effects of burst activity are diagnostic of the burst mechanism and SGRs in general. In the event of detection of substantial burst activity from an SGR, we propose to make Chandra ToO observations of any of the four known sources, SGR 1900+14, SGR 1806-20, SGR 1627-41, SGR 0526-66, the SGR candidate SGR 1801-23, as well as any newly discovered SGR source.

Proposal Number: 09500628

Title: Measuring the Expansion Rate of G266.2-1.2

PI Name: Glenn Allen

Type: GO

We propose to reobserve the bright northwestern rim of G266.2-1.2 five years after our first observation of this region. The goal of the new observation is to measure the expansion rate of the remnant and constrain its age. The age of the remnant is controversial. Some report evidence of line emission associated with the decay to titanium-44, which implies that the remnant must be young (< 1200 yr). Others find no such evidence and argue that the absorption column density favors a large distance (and older) remnant. If the expansion over the last four years < 6.0", then the remnant is too old (> 1200 yr) to have a significant amount of titanium-44 left. If the expansion is much larger, then the results indicate the remnant is young enough to contain a substantial amount of titanium-44.

Proposal Number: 09500752

Title: X-ray Observations of 11 Millisecond Pulsars in M28

PI Name: Jonathan Grindlay

Type: GO

We propose a deep X-ray survey of the globular cluster M28 which will yield a wealth of important and unique science, ranging from the first direct measurement of the magnetic field of a millisecond pulsar and constraints on the neutron star equation of state to likely X-ray/optical (HST) detection of a re-exchanged binary MSP. The proposed joint HST WFPC2 observation will tie the X-ray, optical, and radio data to a common astrometric frame allowing an unambiguous identification of numerous cataclysmic variables and active binaries in M28 as well as making possible the first direct optical detection of a millisecond pulsar.

Proposal Number: 09500789

Title: Constraining GRB physics through their afterglow light curves

PI Name: Evert Rol

Type: TOO

Our current understanding of gamma-ray burst afterglow light curves has become increasingly confused, and the validity of the standard synchrotron fireball model for GRBs is nowadays increasingly questioned. In particular, achromatic breaks due to the lateral expansion of the GRB jet are not substantiated by Swift X-ray observations. It is only through this that the true energies of GRBs are constrained, and that questions such as the true rate of GRBs and the determination of cosmological parameters can be answered. We propose to use CXO to construct the late time X-ray light curves for several Swift bursts. These observations will search for evidence of achromatic jet breaks, providing the necessary insight into the GRB evolution, and the energy and activity of the central engine.

Proposal Number: 09500791

Title: A Chandra observation of the proper motion of RCW 89

PI Name: Yoichi Yatsu

Type: GO

In cycle 6 we observed RCW 89 to resolve fine structure in X-ray band. From the observation we discovered that the X-ray emitting region in RCW 89 are moving away from the pulsar at a velocity of 5000 km/s. The motion of X-ray emitting region may represent the propagation of the shock front driven by the supernova blastwave or the relativistic pulsar jet. And these results can be an evidence for that PSR B 1509-58 and MSH 15-52 (RCW 89) are physically linked. However the calculated velocity has large uncertainty caused by the low quality of the image taken by the first observation of PSR B1509-58 on 2000, in which RCW 89 was on the edge of ACIS-I with worse photon statistics. We therefor propose another 60 ks Chandra observation of RCW 89.

Proposal Number: 09500804

Title: HESS J1731-347: The first TeV pulsar wind nebula from a supersonic pulsar with an X-ray bow shock geometry?

PI Name: Gerd Puehlhofer

Type: GO

We propose to observe the X-ray counterpart to the TeV source HESS J1731-347 in imaging mode with Chandra. Based on our Suzaku observations of the TeV source, we believe that the object can be identified as a pulsar wind nebula driven by a pulsar with supersonic motion. Arcsecond X-ray imaging should reveal the geometry of this object, similar to what is observed with Chandra for the few other examples of this small but interesting class of X-ray pulsar wind nebulae.

Proposal Number: 09500845

Title: Constraining the Continued Rise of SN1996cr

PI Name: Franz Bauer

Type: GO

Recently confirmed SN 1996cr ranks among the closest and X-ray brightest supernovae (SNe) detected on the sky. Past X-ray observations of 1996cr have shown it to have a unique spectral evolution compared to typical type-II SNe, wherein the X-ray flux is still increasing 10 years post-explosion (akin to 1987A). This rising emission is attributed to the ejecta propagating through increasingly dense circumstellar material (e.g., wind) leftover from the past evolution of the supergiant progenitor. We propose an ACIS-S observation of 1996cr to monitor the evolving X-ray spectrum of this unique object and trace back its evolutionary history.

Proposal Number: 09500854

Title: Study of a New Class of Isolated Neutron Star -- 1RXS J141256.0+792204

PI Name: DEREK FOX

Type: GO

We have discovered a new candidate isolated neutron star (INS), the first F_X/F_opt>5000 object to be discovered in seven years, and quite probably the first NS of any sort to be identified in the Galactic halo. Treating the source as analogous to the 7 known INSs implies that, at a height of 4.8 kpc above the Galactic plane, it must have either a very high spatial velocity (> 4800 km/s) or a cooling time much longer than NS cooling theories predict (> 24 Myr). Alternative interpretations of the source as a magnetar or `compact central object' suffer from their own difficulties. We therefore propose to make the first detailed X-ray characterization of this INS, with Chandra observations providing a high S/N CCD-spectrum, investigating long-term variability, and searching for pulsations.

Proposal Number: 09500890

Title: AO9 Chandra Monitoring of SNR 1987A

PI Name: David Burrows

Type: GO

SNR1987A provides a unique opportunity to study the development of a young supernova remnant at high resolution. We have monitored SN/SNR1987A at roughly six month intervals since October 1999. The remnant is expanding and is increasing exponentially in X-ray brightness. We propose to continue this monitoring program with two additional observations in AO9, spaced six months apart. We will perform spatially-resolved spectroscopy in addition to monitoring the expansion and the development of new X-ray hot spots. We do not consider this proposal to conflict with the proposed HRC observations, since our science requires the energy resolution of the ACIS.

Proposal Number: 09500896

Title: TINY HICCUPS TO TITANIC EXPLOSIONS: Tackling Transients in Anomalous X-ray Pulsars

PI Name: Victoria Kaspi

Type: TOO

Recently discovered transient events in Anomalous X-ray Pulsars (AXPs) may be a Rosetta Stone for understanding the persistent emission from magnetars. They also may hold the key to quantifying the number of magnetars in the Galaxy. Here we request Chandra TOO time to observe any AXP following a rare transient event, including a major outburst or a long-duration flare. Specifically, the requested observations will determine the pulsed fraction and spectral evolution of a transient AXP event as the source relaxes back to quiescence, in order to quantitatively test the "twisted magnetosphere" model for magnetars, and establish the basic phenomenology of transient AXP events.

Proposal Number: 09500898

Title: PSRJ1832+0029: a unique probe of pulsar emission physics

PI Name: Duncan Lorimer

Type: GO

We have discovered very unusual behavior in PSR J1832+0029, a 533-ms radio pulsar which switches between on and off states on timescales of several hundred days. Remarkably, the pulsar's spin-down rate almost doubles when the radio emission is on. This is even more dramatic than observed for PSR B1931+24 for which no satisfactory theory presently exists. Unlike PSR B1931+24, J1832+0029 is nearby (1.3 kpc) and an excellent target for X-ray detection. Here we request a 20 ks ACIS observation to study the X-ray emission of PSR J1832+0029 in its on or off state. With a second exposure requested by a companion TOO proposal, the observations would distinguish between radio emission quenching mechanisms that are either intrinsic to the pulsar or caused by accretion from an orbiting companion.

Proposal Number: 09500899

Title: PSRJ1832+0029: a unique target for pulsar emission physics

PI Name: Duncan Lorimer

Type: TOO

We have discovered very unusual behavior in PSR J1832+0029, a 533-ms radio pulsar which switches between on and off states on timescales of several hundred days. Remarkably, the pulsar's spin-down rate almost doubles when the radio emission is on. This is even more dramatic than observed for PSR B1931+24 for which no satisfactory theory presently exists. Unlike PSR B1931+24, J1832+0029 is nearby (1.3 kpc) and an excellent target for X-ray detection. Here we request a 20 ks ACIS TOO to study the X-ray emission of PSR J1832+0029 in its on or off state, triggered by radio monitoring following a companion GO proposal. The observations would distinguish between radio emission quenching mechanisms that are either intrinsic to the pulsar or caused by accretion from an orbiting companion.

Proposal Number: 09610049

Title: Ram Pressure Stripping in the Virgo Cluster - M86 Followup

PI Name: Stephen Murray

Type: GTO

We propose Chandra ACIS-I observations of the "tail" and "head" of M86, a galaxy that is traversing the Virgo cluster with supersonic velocity. The galaxy shows a long tail for which we wish to improve the spectral data by increasing the observing time. In addition, we are searching for a leading shock, either through a surface brightness discontinuity or shocked thermal component in the spectrum. We propose a second pointing at the leading shock region (toward M87) where the ROSAT observation suggests the presence of a sharp feature.

Proposal Number: 09610400

Title: DUST DISKS AND THE EVOLUTION OF S0 GALAXIES

PI Name: Raymond White

Type: GO

We propose Chandra observations of three edge-on S0 galaxies with dusty disks to determine whether their survival against sputtering is due either to their having insubstantial hot atmospheres or ongoing star formation. Since dust is readily destroyed by sputtering in hot atmospheres, one expects only small amounts due to stellar mass loss over a dust sputtering lifetime (~10^7 yr). The more substantial amounts of dust seen in these S0s indicate that dust is replenished by ongoing star formation (either residual secular star formation or that associated with a recent merger) and/or resides in a less hostile sputtering environment: an insubstantial atmosphere characterized by a low X-ray (gas) to optical (stellar) luminosity ratio. Chandra observations can constrain either case.

Proposal Number: 09610464

Title: Dust-to-gas Ratio of High Redshift Galaxies

PI Name: Xinyu Dai

Type: GO

We propose to observe the differential X-ray absorption in three gravitational lenses with significant optical extinctions. By combining the X-ray and optical differential absorption measurements, we will accurately measure the dust-to-gas ratio of the three cosmologically distant galaxies. Combining these new measurements with earlier measurements, we will test whether the dust-to-gas ratio evolves with redshift as predicted by simulations of dust formation and evolution. Such information is to understanding galaxy and star formation and evolution in the presence of an absorbing ISM.

Proposal Number: 09610492

Title: Reading the historical chronicle of activity of the SMBH in NGC5813 using cavities and shocks in the surrounding hot gas

PI Name: William Forman

Type: GO

We propose a deep observation of NGC5813 whose X-ray image shows three pairs of cavities and two shock rings. Combining this observation with the existing data, we can measure the gas temperature and density jumps at the shocks to derive the shock Mach numbers and outburst energies, determine the outburst history by measuring the spatial separation of cavities and shocks, and measure the energy output history of the SMBH by combining the inventory of bubbles and shocks with their ages and models of buoyancy and shock propagation. With its multiple cavities and shocks, NGC5813's X-ray atmosphere provides a rare opportunity to chronicle the activity of its supermassive black hole.

Proposal Number: 09610499

Title: ESO 137-001 in A3627: ISM Stripping and Intracluster X-ray Binaries

PI Name: Ming Sun

Type: GO

Stripping the ISM from disk galaxies in clusters has important effects on both galaxies and the ICM, e.g., galaxy transformation, changes in star formation rates and metal enrichment of the ICM. The gaseous stripped tail also permits tests for important micro-physics. However, X-ray tails of late-type cluster galaxies are rare and we have never had a chance to study one in detail. We propose a 150 ks observation of a spectacular X-ray tail of a small starburst galaxy in the rich cluster A3627, for which a 40 kpc Halpha tail and 28 intergalactic HII regions have recently been found. The deep Chandra exposure is essential to: 1) reveal intracluster ULXs and study the XRB population in the tail, 2) understand stripping of the ISM in the strong ICM wind, and 3) constrain the ICM viscosity.

Proposal Number: 09610593

Title: The X-ray emission of the Lyman-alpha emitting galaxies Haro 2 and ESO338-04

PI Name: Miguel Mas-Hesse

Type: GO

We propose to obtain X ray images and spectra with Chandra ACIS-S of the Lyman alpha emitting starburst galaxies ESO 338-04 and Haro 2, aiming to analyze the proposed correlation between X ray luminosity and Lyalpha emission intensity in compact starbursts. This work will be performed within our current project to characterize in detail the properties of Lyman alpha emitting starburst galaxies in the Local Universe, as a first step to properly understand the Lyman alpha emission observed from high-redshift galaxies.

Proposal Number: 09620024

Title: Black Hole X-ray Novae in M31

PI Name: Stephen Murray

Type: GTO

During A01-7 we found >16 Black Hole X-ray Novae (BHXN) in M31 using Chandra, and with HST followup have estimated orbital periods for 6 of these. Observations are underway with HST to attempt to estimate additional periods. We propose to continue this program,mboth concentrating our scarce HST resources on a single transient which exceeds the NS Eddington limit. Only uninterrupted monitoring can yield the duty cycles and long-term lightcurves of BHXN (and other variables) in M31. Our GO+GTO programs have accumulated 590ks (ACIS+HRC) near the M31 bulge, and total Chandra exposure on M31 is now 940ks. By continuing our monitoring program through AO10 we will reach ~750ks on the bulge and >1Msec total Chandra M31 exposure.

Proposal Number: 09620084

Title: X-ray Localization of the Globular Cluster G1 in M31

PI Name: Albert Kong

Type: GO

Localization of the X-ray emission of the globular cluster G1 in M31 will enable us to determine the origin of the X-ray radiation. From previous X-ray observations, the emission could be either due to accretion of cluster gas by the central intermediate-mass black hole, or a typical luminous low-mass X-ray binary. However, all previous X-ray observations do not allow an accurate relative astrometry. Using Chandra, we can achieve ~0.1" relative astrometry between Chandra and optical images by utilizing multiple X-ray sources with optical counterparts. The accuracy of the astrometry will allow us to determine the nature of the X-ray emission and it may provide an independent evidence for intermediate-mass black hole in G1.

Proposal Number: 09620092

Title: Are the X-Ray Binaries in S0 Galaxies Different From Those in Ellipticals?

PI Name: Craig Sarazin

Type: GO

Chandra images of X-ray faint ellipticals (Es) resolved them into low mass X-ray binaries (LMXBs) plus some emission from ISM. We propose Chandra observations of three X-ray faint S0 galaxies for comparison to ellipticals. We will derive the luminosity functions (LF) of LMXBs and compare to Es; LFs provide direct evidence of the history of massive star formation and a measure of the relative numbers of NS and BH binaries. We will search for variability, limiting the duty cycle of LMXBs. We will hunt for luminous X-ray flares which may be due to microblazars. We expect ~80 LMXBs in globular clusters; we will compare these with similar sources in Es, which can constrain the formation mechanism of field LMXBs. The amount, distribution, and spectrum of any ISM gas emission will be derived.

Proposal Number: 09620136

Title: Continued M31 Monitoring for Black Hole X-ray Nova

PI Name: MICHAEL GARCIA

Type: GO

During A01-7 we found >16 Black Hole X-ray Novae (BHXN) in M31 using Chandra, and with HST followup have estimated orbital periods for 6 of these. Observations are underway with HST to attempt to estimate additional periods. We propose to continue this program, concentrating our scarce HST resources on a single transient which exceeds the NS Eddington limit. Only uninterrupted monitoring can yield the duty cycles and long-term lightcurves of BHXN (and other variables) in M31. Our GO+GTO programs have accumulated 300ks (ACIS) near the M31 bulge, and total ACIS exposure on M31 is now 620ks. Our monitoring program alone can amass 500ks on the bulge if continued through AO12, and combined with other programs will reach >1Msec ACIS exposure on the bulge.

Proposal Number: 09620187

Title: The Remarkably Steady Nature of Luminous LMXBs in Elliptical Galaxies

PI Name: Jimmy Irwin

Type: GO

Multi-epoch Chandra observations of two elliptical galaxies have shown that the most luminous LMXBs are remarkably steady, with none of the 33 >8e38 ergs/s sources in both galaxies having turned off in a 3-5 yr timespan. As a group, the minimum outburst duration must be at least 50 yr such that all of the sources remained on during this time. The two most likely explanations for this behavior is they are transient long-period, wide-orbit red giant black hole LMXBs like GRS1915+105, or persistent ultracompact black hole LMXBs. We propose to reobserve NGC1399 to establish an 8-yr baseline for monitoring its luminous sources. Along with archival data of M87, this will place stringent limits on their outburst duration to distinguish between the two competing scenarios.

Proposal Number: 09620205

Title: Monitoring the brightest ULXs in the Cartwheel

PI Name: Anna Wolter

Type: GO

A Chandra observation detected 16 ULXs, in the starforming southern ring of the Cartwheel, one of the most outstanding and rare examples of intense star formation triggered by the propagation of density waves.Subsequent XMM-Newton data allowed us to witness a flux variation of the brightest of these (source N.10), unraveling its compact nature. We propose a deeper look to explore further the variability properties of N.10, and that of at least 9 of the brightest ULXs, in order to asses their link with the HMXB population. A total of 200 ksec, split in 2 segments, will allow us to obtain crucial details (variability pattern, and possibly spectral shape variation) to assess the physical nature of the sources. The observation will also probe into the physics of the diffuse gas.

Proposal Number: 09620250

Title: Untangling Sombrero's X-ray Emission from Coronally Active Binaries, Cataclysmic Variables, LMXBs, and Hot Gas

PI Name: Christine Jones

Type: GO

We propose a deep (180 ks) ACIS-I observation of the Sombrero galaxy. At a distance of 9 Mpc, this isolated, large bulge Sa galaxy, with a highly inclined disk and surprisingly little X-ray gas, offers a unique opportunity to study the diffuse emission and the point source population. Our primary goals are 1) to examine the contribution to the ISM of mass lost from stars and the energy input to drive a wind from type Ia SN and the central AGN and 2) to take a census of the bulge X-ray populations, including LMXBs, supersoft sources, and the unresolved emission from coronally active binaries (ABs) and CVs and measure their contribution to the diffuse X-ray emission. With ~160 expected globular cluster sources, we will derive the cluster luminosity function.

Proposal Number: 09620513

Title: Galaxies across the Octaves: A Chandra Legacy Survey of SINGS Galaxies

PI Name: Leigh Jenkins

Type: LP

We propose to complete a rich, X-ray unbiased, multiwavelength Legacy dataset for a sample of 40 nearby galaxies. These galaxies are a distance limited (d < 10 Mpc) sample from the Spitzer Infrared Nearby Galaxy Survey (SINGS) Legacy program. The sample is now 45% complete. Our observations will detect X-ray binaries as faint as 3e36-1e37 erg/s, allowing us to constrain the X-ray binary/SFR correlation over a large range of galaxy properties and build X-ray binary Luminosity Functions for galaxies across a range of star formation histories. We will produce Legacy datasets and source catalogs for the community, and run theoretical binary population synthesis models in support of this effort.