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NGC6334CXO - NGC 6334 Chandra X-Ray Point Source Catalog

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Overview

The full stellar population of NGC 6334, one of the most spectacular regions of massive star formation in the nearby Galaxy, has not been well sampled in past studies. The authors have analyzed a mosaic of two Chandra X-ray Observatory images of the region using sensitive data analysis methods, giving a list of 1607 faint X-ray sources with arcsecond positions and approximate line-of-sight absorption. About 95% of these are expected to be cluster members, most lower mass pre-main-sequence stars. Extrapolating to low X-ray levels, the total stellar population is estimated to be 20,000 - 30,000 pre-main-sequence stars. The X-ray sources show a complicated spatial pattern with ~10 distinct star clusters. The heavily obscured clusters are mostly associated with previously known far-infrared sources and radio H II regions. The lightly obscured clusters are mostly newly identified in the X-ray images. Dozens of likely OB stars are found, both in clusters and dispersed throughout the region, suggesting that star formation in the complex has proceeded over millions of years. A number of extraordinarily heavily absorbed X-ray sources are associated with the active regions of star formation.

Catalog Bibcode

2009AJ....138..227F

References

Stellar Clusters in the NGC 6334 Star-Forming Complex
    Feigelson E.D., Martin A.L., McNeill C.J., Broos, P.B., Garmire, G.P.
   <Astr. J. 138, 227 (2009)>
   =2009AJ....138..227F

Provenance

This table was created by the HEASARC in August 2009 based on the electronic version of table 1 from the above reference which were obtained from the AJ web site.

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 '[FMM2009]' prefix (for Feigelson, Martin, McNeill 2009) and the X-ray source number (this was created by the HEASARC in anticipation of its recommendation by the CDS Dictionary of Nomenclature of Celestial Objects).

Name
The IAU-style X-ray source designation using the standard 'CXOU' prefix for Chandra sources, and the J2000.0 coordinates, e.g., 'CXOU JHHMMSS.ss+DDMMSS.s'. Notice that these designations are given to higher precision than the current standard CDS-recommended naming convention for such sources, viz., e.g., 'CXOU JHHMMSS.s+DDMMSS'.

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.

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.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Error_Radius
The estimated 1-sigma random position error, in arcseconds. This was computed as ({sigma}_x2 + {sigma}_y2). The single-axis position errors, {sigma}_x and {sigma}_y, were estimated from the single-axis standard deviations of the PSF inside the extraction region and the number of counts extracted.

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 average of the Poisson upper and lower 1-sigma error in the X-ray source net counts (including the background contribition).

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 for the X-ray source 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 that is 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.

Log_Bck_Prob_Limit
This flag parameter is set to '<' if the quoted background probability is an upper limit.

Log_Bck_Prob
The logarithm of the probability that the extracted total-band (0.5 - 8 keV) counts are solely from fluctuations in the local background, based on Poisson statistics.

Median_Energy
The background-corrected median photon energy for the photons from the X-ray source in the total band, in keV.

Kmag_Limit
This flag is set to '>' to indicate that the source was detected in the J or H bands in the 2MASS Point Source Catalog, but not in the K-s band.

Kmag
The 2MASS K_s band magnitude of an infrared counterpart lieing within 1 arcsecond of the X-ray source position.

Kmag_Flag
This flag is set to ':' to indicate that the K_s magnitude is affected by photometric confusion by a nearby star or by nebular emission, or that the photometric accuracy is worse than +/- 0.2 magnitudes.

Ctrprt_Names
The name(s) of possible counterparts within 3 arcseconds of the X-ray source in the SIMBAD database of published objects. FIR-V sources are from Straw & Hyland (1989, ApJ, 340, 318), TPR stars are from Tapia et al. (1996, A&A, 316, 102), and other designations are discussed in the text of the reference paper.


Contact Person

Questions regarding the NGC6334CXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 3-Aug-2009