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CEPBOB3CXO - Cep B/OB3 Star-Forming Region Chandra X-Ray Point Source Catalog

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Overview

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.


Catalog Bibcode

2006ApJS..163..306G

References

Chandra Study of the Cepheus B Star Forming Region: Stellar Populations and
the Initial Mass Function.
    Getman K.V., Feigelson E.D., Townsley L., Broos P., Garmire G.,
    Tsujimoto, T.
   <Astrophys. J. Suppl., 163, 306-334 (2006)>
   =2006ApJS..163..306G

Provenance

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.

Parameters

Source_Number
A running X-ray source number in order of increasing J2000.0 Right Ascension.

Alt_Name
An alternative name for the catalogued X-ray source based on the '[GFT2006]' prefix (for Getman, Feigelson and Townsley 2006) and the source number, as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

Name
The preferred IAU source designation for the X-ray source using the 'CXOCepB' prefix registered with the CDS Dictionary of Nomenclature of Celestial Objects, and the truncated J2000.0 coordinates (JHHMMSS.ss+DDMMSS.s).

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 decimal degree coordinates to a precision of 10-6 degrees in the original table. An astrometric correction of +0.13" in RA was applied to the original Chandra positions in order to bring them into the 2MASS/Hipparcos reference frame.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 decimal degree coordinates to a precision of 10-6 degrees in the original table. An astrometric correction of -0.14" in Dec was applied to the original Chandra positions in order to bring them into the 2MASS/Hipparcos reference frame.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Off_Axis
The off-axis angle of the X-ray source from the nominal pointing direction, in arcminutes.

Counts
The estimated net counts from the extraction area for the X-ray source in the total energy band (0.5 - 8.0 keV).

Counts_Error
The 1-sigma error in the net total-band counts.

Bck_Counts
The estimated background counts from the extraction area for the X-ray source in the total energy band (0.5 - 8.0 keV).

HB_Counts
The estimated net counts from the extraction area in the hard energy band (2.0 - 8.0 keV).

PSF_Fraction
The fraction of the point-spread function (PSF) at the fiducial energy of 1.497 keV enclosed within the extraction area for the X-ray source. Note that a reduced PSF fraction (significantly below 90%) may indicate that the source is in a crowded region or on the edge of the field.

SNR
The X-ray source significance (in sigma).

Anomalies_Flag
This parameter contains flags indicating the presence of source anomalies:

  g = fractional time when source was on a detector (FRACEXPO from mkarf) is <0.9
  e = source on field edge
  

Variable_Flag
This parameter contains flags which characterize the presence or absence of source variability based on K-S statistics:

  a = no evidence for variability
  b = possibly variable
  c = definitely variable
    = no test was performed for sources with <4 total full-band counts,
      or sources in chip gaps or on field edges
  

Exposure
The effective exposure time of the X-ray source, in seconds.

Median_Energy
The background-corrected median photon energy MedE in the total energy band, in keV.

TwoMASS_Name
The 2MASS counterpart to the X-ray source.

Offset
The Chandra-2MASS positional offset, in arcseconds.

Jmag
The 2MASS J-band magnitude of the infrared counterpart to the X-ray source.

Hmag
The 2MASS H-band magnitude of the infrared counterpart to the X-ray source.

Kmag
The 2MASS Ks-band magnitude of the infrared counterpart to the X-ray source.

Quality_Flag_2MASS
The 2MASS photometric quality flags, namely the ph_qual_flag provided in the 2MASS All-Sky Data Release, where the three characters refer to the J, H, Ks bands, as follows:

       A = very high significance detection (>10 SNR)
       B = high significance detection (>7 SNR)
       C = moderate significance detection (>5 SNR)
       D = low significance detection
       E = point-spread fitting poor
       F = reliable photometric errors not available
       U = upper limit on magnitude (source not detected)
       X = source is detected but no valid brightness estimate is available
  

Contcon_Flag_2MASS
The 2MASS contamination and confusion flags, namely the cc_flg provided in the 2MASS All-Sky Data Release where the three characters refer to the J, H, Ks bands, as follows:

       0 = source unaffected by artifacts
       b = band-merge confusion (possible multiple source)
       c = photometric confusion from nearby star
       d = diffraction spike confusion from nearby star
       p = persistence contamination from nearby star
       s = electronic stripe from nearby star
  

A_Vmag
The visual absorption of the counterpart, in magnitudes, derived from the color-magnitude diagram by dereddening the 2MASS photometric colors to the 1 Myr PMS isochrone.

Stellar_Mass
The stellar mass of the counterpart, in solar masses, derived from the color-magnitude diagram by dereddening the 2MASS photometric colors to the 1 Myr PMS isochrone.

Log_L_Bol
The logarithm of the stellar bolometric luminosity of the counterpart, in solar luminosities, derived from the color-magnitude diagram by dereddening the 2MASS photometric colors to the 1 Myr PMS isochrone.

Log_NH
The logarithm of the estimated hydrogen column density to the X-ray source, in atoms per square cm, derived from spectral fitting.

Te_Plasma
The plasma temperature of the X-ray source, in keV, derived from spectral fitting.

Log_Lx_HB
The logarithm of the observed hard-band (2.0 - 8.0 keV) X-ray luminosity, in erg/s, obtained from spectral analysis (see Section 4 of the published paper for more details).

Log_Lx_HB_Error
The estimated error in the logarithm of the observed hard-band X-ray luminosity, in erg/s, obtained from spectral analysis (see Section 4 of the published paper for more details), and from simulations.

Log_Lx_HB_Corr
The logarithm of the hard-band (2.0 - 8.0 keV) X-ray luminosity, in erg/s, obtained from spectral analysis (see Section 4 of the published paper for more details), and corrected for absorption.

Log_Lx_HB_Corr_Error
The estimated error in the logarithm of the absorption-corrected hard-band X-ray luminosity, in erg/s, obtained from spectral analysis (see Section 4 of the published paper for more details), and from simulations.

Log_Lx
The logarithm of the observed total-band (0.5 - 8.0 keV) X-ray luminosity, in erg/s, obtained from spectral analysis (see Section 4 of the published paper for more details).

Log_Lx_Error
The estimated error in the logarithm of the observed total-band X-ray luminosity, in erg/s, obtained from spectral analysis (see Section 4 of the published paper for more details), and from simulations.

Log_Lx_Corr
The logarithm of the total-band (0.5 - 8.0 keV) X-ray luminosity, in erg/s, obtained from spectral analysis (see Section 4 of the published paper for more details), and corrected for absorption.

Log_Lx_Corr_Error
The estimated error in the logarithm of the absorption-corrected total-band X-ray luminosity, in erg/s, obtained from spectral analysis (see Section 4 of the published paper for more details), and from simulations.

Source_Flag
This parameter contains flags which summarize the spectral method, source membership, and K-disk star information, as follows:

  b =  spectral results from spectral fits of 174 relatively "bright" sources
       with > 20 net counts
  w =  spectral results from N_(H,IR) - MedE interpolation for 212 "weak"
       sources with known N_(H,IR)
  v =  spectral results from fits of ungrouped spectra for 45 "weak" sources
       with unknown N_(H,IR)
  e =  possible members of the embedded cluster
  l =  possible members of the lightly absorbed cluster
  o =  other possible members, found in the molecular cloud, not related to
       the embedded cluster
  a =  AGN candidates
  f =  field star candidates
  d =  possible K-band excesses associated circumstellar disks
  0 =  stars with no K-band excesses or unknown
  

Contact Person

Questions regarding the CEPBOB3CXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 19-Mar-2015