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Proposal Number: 09300001

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

PI Name: Wolfgang Pietsch

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

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

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

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

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

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.

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