ROSAT PSPC Catalog of Canis Major R1 X-Ray Sources

ROSAT PSPC Catalog of Canis Major R1 X-Ray Sources CMAR1XRAY ivo://nasa.heasarc/cmar1xray NASA/GSFC HEASARC Gregorio-Hetem et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The CMa R1 star-forming region contains several compact clusters as well as many young early-B stars. It is associated with a well-known bright rimmed nebula, the nature of which is unclear (fossil HII region or supernova remnant). To help elucidate the nature of the nebula, the authors' goal was to reconstruct the star-formation history of the CMa R1 region, including the previously unknown older, fainter low-mass stellar population, using X-rays. The authors analyzed images obtained with the ROSAT satellite, covering ~5 square degrees. Complementary VRI photometry was performed with the Gemini South telescope. Color-magnitude and color-color diagrams were used in conjunction with pre-main sequence evolutionary tracks to derive the masses and ages of the X-ray sources. The ROSAT images show two distinct clusters. One is associated with the known optical clusters near Z CMa, to which ~ 40 members are added. The other, which the authors name the "GU CMa" cluster, is new, and contains ~ 60 members. The ROSAT sources are young stars with masses down to M_star ~ 0.5 M_sun, and ages up to 10 Myr. The mass functions of the two clusters are similar, but the GU CMa cluster is older than the cluster around Z CMa by at least a few Myr. Also, the GU CMa cluster is away from any molecular cloud, implying that star formation must have ceased; on the contrary (as already known), star formation is very active in the Z CMa region. The two ROSAT observations that the authors analyzed are the following. By order of increasing RA, the first Field ('Field 1' hereafter), HEASARC ID RP201011 pointing axis RA(J2000} = 7h 00m, Dec(J2000) = -11o 30', has an exposure of 19.7 ks. 'Field 2', HEASARC ID RP201277, pointing axis RA(J2000) = 7h 04m, Dec(J2000) = -11o 33', has a much shorter exposure of 4.6 ks. This table contains the complete list of sources detected in CMa R1 by ROSAT. This online catalog was created by the HEASARC in April 2010 based on machine-readable tables obtained from the CDS (their catalog J/A+A/506/711, file tablea1.dat). This is a service provided by NASA HEASARC . 2009A&A...506..711G https://heasarc.gsfc.nasa.gov/W3Browse/all/cmar1xray.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=cmar1xray& GET text/xml 180 99999 true 104.87916667 -11.97166667 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=cmar1xray GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_cmar1xray&Action=More+Options&Action=Parameter+Search&ConeAdd=1 ROSAT 0.0166666666666667 X-ray public cmar1xray ROSAT PSPC Catalog of Canis Major R1 X-Ray Sources name Catalog 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 error_radius Diameter of the Position Error Circle (arcsec) arcsec stat.error;pos short nullable count_rate X-Ray Count Rate ct/s phot.count;em.X-ray.soft double nullable count_rate_error RMS Uncertainty in X-Ray Count Rate ct/s stat.error;phot.count;em.X-ray.soft double nullable log_lx Logarithm of X-Ray Luminosity (in erg/s) log(erg/s) phys.luminosity;em.X-ray.soft double nullable rmag R Magnitude mag phot.mag;em.opt.R double nullable jmag 2MASS J Magnitude mag phot.mag;em.IR.J 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 lii Galactic Longitude degree pos.galactic.lon double nullable other_xray_flag Flag [x] Indicates Objects Detected by XMM-Newton and/or Chandra meta.code;phot;em.X-ray char nullable source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable upper_age Second Value of Age When Interval Myr time.age short nullable snr X-Ray Signal-to-Noise Ratio stat.snr;em.X-ray.soft double nullable age_flag Flag [?] Indicates Uncertainty in Age meta.code;time.age char nullable bii Galactic Latitude degree pos.galactic.lat double nullable mass_flag Flag [?] Indicates Uncertainty in Mass meta.code;phys.mass char nullable mass Mass Estimation Based on Near-IR Data Solar_Mass phys.mass double nullable mass_limit Limit Flag for Mass meta.code;phys.mass char nullable hk_excess_flag Flag [e] Indicates H-K Excess in Relevant Source meta.note;phot.color.excess char nullable age_limit Limit Flag for Age meta.code;time.age char nullable a_vmag Extinction in V Band mag phys.absorption;em.opt.V double nullable source_flags Flags Indicates Individual Notes Regarding Source char nullable age Age Estimation Based on Near-IR Data Myr time.age short nullable hmag 2MASS H Magnitude mag phot.mag;em.IR.H double nullable upper_mass Second Value of Mass When Interval Solar_Mass phys.mass double nullable kmag 2MASS K Magnitude mag phot.mag;em.IR.K double nullable position_flag Flag [X] Indicates Uncertainty in Optical Position meta.code;pos char nullable