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RCW38CXO2 - RCW 38 Chandra X-Ray Point Source Catalog 2

HEASARC
Archive

Overview

This table contains some of the results from a study of the structure of the high-mass star-forming region RCW 38 and the spatial distribution of its young stellar population. Spitzer Infrared Array Camera (IRAC) photometry (3-8 micron) is combined with Two Micron All Sky Survey (2MASS) near-IR data to identify young stellar objects (YSOs) by IR-excess emission from their circumstellar material. Chandra X-ray data are used to identify class III pre-main-sequence stars lacking circumstellar material. The authors identify 624 YSOs: 23 class 0/I and 90 flat spectrum (FS) protostars, 437 class II stars, and 74 class III stars. They also identify 29 (27 new) O star candidates over the IRAC field. Seventy-two stars exhibit IR-variability, including 7 class 0/I and 12 flat spectrum YSOs. A further 177 tentative candidates are identified by their location in the IRAC [3.6] versus [3.6]-[5.8] color-magnitude diagram. The authors find strong evidence of subclustering in the region. Three subclusters were identified surrounding the central cluster, with massive and variable stars in each subcluster. The central region shows evidence of distinct spatial distributions of the protostars and pre-main-sequence stars. A previously detected IR cluster, DB2001_Obj36, has been established as a subcluster of RCW 38. This suggests that star formation in RCW 38 occurs over a more extended area than previously thought. The gas-to-dust ratio is examined using the X-ray derived hydrogen column density, NH and the K-band extinction, and found to be consistent with the diffuse interstellar medium, in contrast with Serpens and NGC 1333. The authors posit that the high photoionizing flux of massive stars in RCW 38 affects the agglomeration of the dust grains.

This table contains the list of 536 X-ray sources found in the Chandra data using a three-pass method with the CIAO 3.4 Wavdetect tool.


Catalog Bibcode

2011ApJ...743..166W

References

The Structure of the Star-forming Cluster RCW 38
    Winston E., Wolk S.J., Bourke T.L., Megeath S.T., Gutermuth R.,
    Spitzbart B.
   <Astrophys. J., 743, 166 (2011)>
   =2011ApJ...743..166W

Provenance

This table was created by the HEASARC in January 2012 based on an electronic version of Table 2 from the reference paper which was obtained from the ApJ web site.

Parameters

Source_Number
A unique sequential identification number for each Chandra source.

Name
The name for the Chandra source. This was created by the HEASARC using the usual 'CXOU' prefix (for Chandra X-ray Observatory, Unregistered) and the J2000.0 equatorial coordinates in the style recommended by the Dictionary of Nomenclature of Celestial Objects, e.g., 'CXOU J085953.6-472846'.

RA
The Right Ascension of the Chandra X-ray source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original reference.

Dec
The Declination of the Chandra X-ray source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 arcseconds in the original reference.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Raw_Counts
The raw counts in the X-ray source, in the Chandra band, 0.3 - 8.0 keV.

Counts
The net (background-subtracted and aperture-corrected) counts in the X-ray source, in the Chandra band, 0.3 - 8.0 keV.

Obs_Flux
The observed (absorbed) flux of the X-ray source, in erg s-1 cm-2, in the Chandra band, 0.3 - 8.0 keV.

Flux
The total unabsorbed (absorption-corrected) flux of the X-ray source, in erg s-1 cm-2, in the Chandra band, 0.3 - 8.0 keV.

NH
The H I column density towards the X-ray source, in H atoms cm-2.

NH_Error
The uncertainty in the H I column density towards the X-ray source, in H atoms cm-2.

kT
The plasma temperature inferred from the spectrum of the X-ray source, in keV.

kT_Error
The uncertainty in the plasma temperature inferred from the spectrum of the X-ray source, in keV.

Chi_Squared
The reduced chi-squared of the best-fit model spectrum to the observed spectrum.


Contact Person

Questions regarding the RCW38CXO2 database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 10-Jan-2012