The ChaMP Extended Stellar Survey (ChESS): Photometric and Spectroscopic Properties of Serendipitously Detected Stellar X-ray Sources

Abstract

We present 348 X-ray emitting stars identified from correlating the Extended Chandra Multiwavelength Project (ChaMP), a serendipitous wide-area X-ray survey, with the Sloan Digital Sky Survey (SDSS). We use morphological star/galaxy separation, an SDSS quasar catalog, an optical color-magnitude cut, and X-ray data quality tests to create our catalog, the ChaMP Extended Stellar Survey (ChESS), from a sample of 2121 matched ChaMP/SDSS sources. Our cuts retain 92% of the spectroscopically confirmed stars while excluding 99.6% of the 684 spectoscopically confirmed extragalactic sources. Fewer than 3% of the sources in our final catalog are previously identified stellar X-ray emitters; we expect ~10% of the catalog is composed by giants, and identify seven giant stars and three cataclysmic variables. We derive distances, X-ray and bolometric luminosities for these stars, revealing that this catalog fills the gap between the nearby stars identified by the ROSAT All-Sky Survey and the more distant stars detected in deep Chandra and XMM-Newton surveys. For 36 newly identified X-ray emitting M stars we calculate L_(Halpha)/L_(bol). L_(Hα)/L_(bol) and L_(X)/L_(bol) are linearly related below L_(X)/L_(bol) ~ 3 x 10^(-4), while L_(Halpha)/L_(bol) appears to turn over at larger L_(X)/L_(bol) values. Stars with reliable SDSS photometry have an ~0.1 mag blue excess in (u-g), likely due to increased chromospheric continuum emission. Photometric metallicity estimates suggest the sample is split between the young and old disk populations of the Galaxy; the lowest activity sources belong to the old disk population, a clear signature of the decay of magnetic activity with age. Future papers will present analyses of source variability and comparisons of this catalog to models of stellar activity in the Galactic disk.

21 pages, 12 figures, emulateapj format. Accepted for publication in ApJS. Tables 2 and 3 shown as stubs, and figures degraded to meet resolution limits. Full resolution version available from http://www.cfa.harvard.edu/~kcovey/ChESS.fullres.ps

References in corpus (13)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample
• Stellar SEDs from 0.3-2.5 Microns: Tracing the Stellar Locus and Searching for Color Outliers in SDSS and 2MASS
• The Stellar Populations of Praesepe and Coma Berenices
• The first XMM-Newton slew survey catalogue: XMMSL1
• Low-Mass Dwarf Template Spectra from the Sloan Digital Sky Survey
• The Luminosity Function of X-ray Selected Active Galactic Nuclei: Evolution of Supermassive Black Holes at High Redshift
• Chandra Multiwavelength Project X-ray Point Source Catalog
• Chandra Multiwavelength Project X-ray Point Source Number Counts and the Cosmic X-ray Background
• A Large, Uniform Sample of X-ray Emitting AGN from the ROSAT All-Sky and Sloan Digital Sky Surveys: the Data Release 5 Sample
• ChaMP Serendipitous Galaxy Cluster Survey
• The stellar content of the XMM-Newton Bright Serendipitous Survey
• Source Matching in the SDSS and RASS: Which Galaxies are Really X-ray Sources?

Cited by in corpus (8)

• The Factory and The Beehive II. Activity and Rotation in Praesepe and the Hyades
• M Dwarfs in SDSS Stripe 82: Photometric Light Curves and Flare Rate Analysis
• On the Age of the TRAPPIST-1 System
• The Spatial Clustering of ROSAT All-Sky Survey AGN: I. The cross-correlation function with SDSS Luminous Red Galaxies
• X-Ray-Emitting Stars Identified from the ROSAT All-Sky Survey and the Sloan Digital Sky Survey
• The stellar content of the ROSAT all-sky survey
• Classification of 4XMM-DR9 Sources by Machine Learning
• Constraints on the ubiquity of coronal X-ray cycles