ChaMP Extended Stellar Survey (ChESS) X-Ray Catalog

ChaMP Extended Stellar Survey (ChESS) X-Ray Catalog CHESSCAT ivo://nasa.heasarc/chesscat NASA/GSFC HEASARC Covey et al. 2026-10-02 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The ChaMP Extended Stellar Survey (ChESS) X-ray catalog contains 348 X-ray-emitting stars identified from correlating the Extended Chandra Multiwavelength Project (ChaMP), a wide-area serendipitous survey based on archival X-ray images, with the Sloan Digital Sky Survey (SDSS). The authors used morphological star/galaxy separation, matching to an SDSS quasar catalog, an optical color-magnitude cut, and X-ray data-quality tests to create this catalog, from a sample of 2121 matched ChaMP/SDSS sources. Their cuts retain 92% of the spectroscopically confirmed stars in the original sample while excluding 99.6% of the 684 spectroscopically confirmed extragalactic sources. Fewer than 3% of the sources in their final catalog are previously identified stellar X-ray emitters. For 42 catalog members, spectroscopic classifications are available in the literature. New spectral classifications and H-alpha measurements are presented for an additional 79 stars. The catalog is dominated by main-sequence stars; the authors estimate the fraction of giants in ChESS to be ~10%. They identify seven giant stars (including a possible Cepheid and an RR Lyrae star) as ChaMP sources, as well as three cataclysmic variables. They derive distances from ~10 to 2000 pc for the stars in the catalog using photometric parallax relations appropriate for dwarfs on the main sequence and calculate their X-ray and bolometric luminosities. These stars lie in a unique space in the LX-distance plane, filling the gap between the nearby stars identified as counterparts to sources in 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, the authors calculated LH-alpha/Lbol. The quantities LH-alpha/Lbol and LX/Lbol are linearly related below LX/Lbol ~ 3 x 10-4, while LH-alpha/Lbol appears to turn over at larger LX/Lbol 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 that the sample is evenly 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. This table was created by the HEASARC in January 2009 based on the electronic version of Tables 2 and 3 from the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC . 2008ApJS..178..339C https://heasarc.gsfc.nasa.gov/W3Browse/all/chesscat.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=chesscat& GET text/xml 180 99999 true 340.91625 -9.563333333333 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=chesscat GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_chesscat&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray Optical public chesscat ChaMP Extended Stellar Survey (ChESS) X-Ray Catalog name CXOMP Source Designation meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable counts Net Broadband (0.3-8.0 keV) X-Ray Counts ct phot;em.X-ray double nullable counts_error Uncertainty in Net Broadband (0.3-8.0 keV) X-Ray Counts ct stat.error;phot;em.X-ray double nullable flux Broadband (0.3-8.0 keV) X-Ray Flux (erg/s/cm^2) erg/s/cm^2 phot.flux;em.X-ray double nullable flux_error Uncertainty in Broadband (0.3-8.0 keV) X-Ray Flux (erg/s/cm^2) erg/s/cm^2 stat.error;phot.flux;em.X-ray double nullable off_set Separation Between SDSS and Chandra Positions (arcsec) arcsec pos.angDistance;em.X-ray;em.opt double nullable imag SDSS i Band Magnitude mag phot.mag;em.opt.I double nullable imag_error Uncertainty in SDSS i Band Magnitude mag stat.error;phot.mag;em.opt.I double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable jh_color_error Uncertainty in J-H mag stat.error;phot.color;em.IR.J;em.IR.H double nullable synth_gmag_error Uncertainty in Synthetic SDSS g Band Magnitude mag stat.error;phot.mag;em.opt double nullable gr_color_error Uncertainty in g-r mag stat.error;phot.color;em.opt double nullable bii Galactic Latitude degree pos.galactic.lat double nullable sb_counts Net Soft (0.5-2.0 keV) X-Ray Counts ct phot;em.X-ray.soft double nullable obsid Chandra Observation Identification meta.id;obs short nullable jmag 2MASS J Band Magnitude mag phot.mag;em.IR.J double nullable synth_gmag Synthetic SDSS g Band Magnitude mag phot.mag;em.opt double nullable source_flags Flag(s) [bcde] Indicating Note(s) about Source meta.code char nullable sdss_saturation_flag Flag [0-2] Indicates SDSS Saturation meta.code short nullable gr_color SDSS (g-r) color mag phot.color;em.opt double nullable hardness_ratio Hardness Ratio phot.flux;arith.ratio;em.X-ray double nullable iz_color_error Uncertainty in i-z mag stat.error;phot.color;em.opt double nullable jh_color 2MASS (J-H) Color mag phot.color;em.IR.J;em.IR.H double nullable ri_color SDSS (r-i) color mag phot.color;em.opt double nullable log_lx_lbol Log of Ratio of 0.3-8.0 keV to Bolometric Luminosities phys.luminosity;arith.ratio double nullable lii Galactic Longitude degree pos.galactic.lon double nullable sb_flux_error Uncertainty in Soft (0.5-2.0 keV) X-Ray Flux (erg/s/cm^2) erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable log_sb_lx_lbol_error Uncertainty in Log of Ratio of 0.5-2.0 keV to Bolometric Luminosities stat.error;phys.luminosity;arith.ratio double nullable log_sb_lx Log of Soft (0.5-2.0 keV) X-Ray Luminosity (in units of erg/s) log(erg/s) phys.luminosity;em.X-ray.soft double nullable ug_color SDSS (u-g) Color mag phot.color;em.opt double nullable log_sb_lx_error Uncertainty in Log of Soft (0.5-2.0 keV) X-Ray Luminosity (in units of erg/s) log(erg/s) stat.error;phys.luminosity;em.X-ray.soft double nullable hk_color_error Uncertainty in H-K_s_ mag stat.error;phot.color;em.IR.H;em.IR.K double nullable jmag_error Uncertainty in 2MASS J Band Magnitude mag stat.error;phot.mag;em.IR.J double nullable log_sb_lx_lbol Log of Ratio of 0.5-2.0 keV to Bolometric Luminosities phys.luminosity;arith.ratio double nullable log_lx Log of Broadband (0.3-8.0 keV) X-Ray Luminosity (in units of erg/s) log(erg/s) phys.luminosity;em.X-ray double nullable ri_color_error Uncertainty in r-i mag stat.error;phot.color;em.opt double nullable log_lx_error Uncertainty in Log of Broadband X-Ray Luminosity (in units of erg/s) log(erg/s) stat.error;phys.luminosity;em.X-ray double nullable sb_counts_error Uncertainty in Net Soft (0.5-2.0 keV) X-Ray Counts ct stat.error;phot;em.X-ray.soft double nullable sb_flux Soft (0.5-2.0 keV) X-Ray Flux (erg/s/cm^2) erg/s/cm^2 phot.flux;em.X-ray.soft double nullable ug_color_error Uncertainty in u-g mag stat.error;phot.color;em.opt double nullable log_lx_lbol_error Uncertainty in Log of Ratio of 0.3-8.0 keV to Bolometric Luminosities stat.error;phys.luminosity;arith.ratio double nullable hk_color 2MASS (H-K_s_) Color mag phot.color;em.IR.H;em.IR.K double nullable iz_color SDSS (i-z) color mag phot.color;em.opt double nullable