CEPBOB3CXO ivo://nasa.heasarc/cepbob3cxo NASA/GSFC HEASARC Getman et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains the Cepheus B star formation region (the Cep B molecular cloud and the Cep OB3b OB association) Chandra X-Ray point source catalog. The Cepheus B (Cep B) molecular cloud and a portion of the nearby Cep OB3b OB association, one of the most active regions of star formation within 1 kpc, have been observed with the ACIS detector on board the Chandra X-Ray Observatory. 431 X-ray sources have been detected, of which 89% are confidently identified as clustered pre-main-sequence (PMS) stars. Two main results are obtained. First, the best census to date for the stellar population of the region has been made, with many members of two rich stellar clusters, the lightly obscured Cep OB3b association and the deeply embedded cluster in Cep B, whose existence was previously traced only by a handful of radio sources and T Tauri stars, being identified. Second, a discrepancy between the X-ray luminosity functions of the Cep OB3b and the Orion Nebula cluster has been found. This may be due to the different initial mass functions of the two regions (an excess of ~=0.3 M_solar stars) or different age distributions. Several other results are obtained. A diffuse X-ray component seen in the field is attributed to the integrated emission of unresolved low-mass PMS stars. The X-ray emission from HD 217086 (O7n), the principle ionizing source of the region, follows the standard model, involving many small shocks in an unmagnetized radiatively accelerated wind. X-ray source 294 joins a number of similar superflare PMS stars for which long magnetic structures may connect the protoplanetary disk to the stellar surface. The Chandra observation of Cep B and Cep OB3b was obtained on 2003 March 11.51-11.88 with the ACIS camera. Only results from the imaging array (ACIS-I) covering about 17' x 17' on the sky are considered here. The aim point of the array was 22 56 49.4 +62 39 55.6 (J2000.0 RA and Dec), and the satellite roll angle was 7.9 degrees. The total net exposure time was 30 ksec, with no background flaring or data losses. This table was created by the HEASARC in February 2007 based on the merger of electronic versions of tables 1, 2 and 3 from the above reference which were obtained from the ApJS website. This is a service provided by NASA HEASARC . 2006ApJS..163..306G https://heasarc.gsfc.nasa.gov/W3Browse/all/cepbob3cxo.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=cepbob3cxo& GET text/xml 180 99999 true 344.009031 62.510958 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=cepbob3cxo GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_cepbob3cxo&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 Infrared X-ray public cepbob3cxo Cep B/OB3 Star-Forming Region Chandra X-Ray Point Source Catalog source_number CepB Source Number meta.id short nullable name IAU Source Designation (CXOCEPB+) meta.id;meta.main char nullable twomass_name 2MASS Source Identification 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 Total Band (0.5-8.0 keV) Counts ct phot;em.X-ray double nullable counts_error Error in Net Total Band Counts ct stat.error;phot;em.X-ray double nullable log_lx_corr Log of Estimated Total Band Luminosity Corrected for Absorption log(erg/s) double nullable jmag SDSS J Band Brightness mag 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 log_lx Log of Observed Total Band (0.5-8.0 keV) Luminosity log(erg/s) double nullable log_lx_hb_corr Log of Estimated Hard Band Luminosity Corrected for Absorption log(erg/s) double nullable log_lx_hb Log of Observed Hard Band (2.0-8.0 keV) Luminosity log(erg/s) double nullable alt_name Alternative Catalog Source Designation meta.id char nullable log_lx_error Error in Log of Observed Total Band Luminosity from Simulations log(erg/s) double nullable te_plasma Plasma Energy (keV) keV double nullable hmag SDSS H Band Brightness mag double nullable bii Galactic Latitude degree pos.galactic.lat double nullable log_lx_corr_error Error in Log of Absorption-Corrected Total Band Luminosity from Simulations log(erg/s) double nullable variable_flag Flag Indicates Source Variability from K-S Test char nullable quality_flag_2mass Flag Indicates 2MASS Photometric Quality char nullable median_energy Median Energy in Total Band Corrected for Background (keV) keV double nullable log_lx_hb_error Error in Log of Observed Hard Band Luminosity from Simulations log(erg/s) double nullable log_nh Log of the Hydrogen Column Density log(H-atoms/cm^2) double nullable psf_fraction Point Spread Fraction in Extracted Area at Fiducial Energy 1.5 keV double nullable contcon_flag_2mass Flag Indicates 2MASS Contamination and Confusion char nullable lii Galactic Longitude degree pos.galactic.lon double nullable anomalies_flag Flags Indicates Source Anomalies char nullable off_set Chandra-2MASS Source Positional Offset (arcsec) arcsec double nullable a_vmag Visual Absorption mag double nullable hb_counts Net Hard Band (2.0-8.0 keV) Counts ct double nullable bck_counts Background Total Band (0.5-8.0 keV) Counts extracted ct double nullable log_l_bol Log of Stellar Bolometric Luminosity (in Units of Solar Luminosity) log(Solar_Luminosity) double nullable stellar_mass Stellar Mass Solar_Mass double nullable off_axis Off-Axis Angle (arcmin) arcmin instr.offset double nullable log_lx_hb_corr_error Error in Log of Absorption-Corrected Hard Band Luminosity from Simulations log(erg/s) double nullable kmag SDSS K_s Band Brightness mag double nullable snr Source Significance (in sigma) stat.snr double nullable exposure Effective Exposure (s) s time.duration;obs.exposure double nullable source_flag Flags Indicate Spectroscopy Method, Source Membership, and Stars with K-Disks char nullable