LMC30DRCXO - LMC 30 Doradus Complex Chandra X-Ray Point Source Catalog
This table contains the results of a study of the X-ray
point-source population of the 30 Doradus (30 Dor) star-forming complex in
the Large Magellanic Cloud (LMC) using high spatial-resolution X-ray images
and spatially-resolved spectra obtained with the Advanced CCD Imaging
Spectrometer (ACIS) on board the Chandra X-Ray Observatory. The observation
of ~21 ks was made on 1999 September 21 and placed the cluster R136 at the
aim point of the ACIS Imaging Array (ACIS-I). This table lists the
the X-ray sources detected in the 17' x 17' field centered on R136, the
massive star cluster which lies at the center of the main 30 Dor nebula.
20 of the 32 Wolf-Rayet stars in the ACIS field are detected. The cluster
R136 is resolved at the subarcsecond level into almost 100 X-ray sources,
including many typical O3-O5 stars, as well as a few bright X-ray sources
which hade been previously reported. Over 2 orders of magnitude of scatter
in the X-ray luminosity L_x (calculated assuming a distance of 50 kpc) is
seen among R136 O stars, suggesting that X-ray emission in the most massive
stars depends critically on the details of wind properties and the binarity
of each system, rather than reflecting the widely reported characteristic
value L_x/L_bol ~10^-7. Such a canonical ratio may exist for single massive
stars in R136, but these data are too shallow to confirm this relationship.
Through this and more recent X-ray studies of 30 Dor, the complete life
cycle of a massive stellar cluster can be revealed.
This HEASARC table contains both the primary high-significance X-ray sources
as well as some lower-significance tentative X-ray sources. The latter
sources should not be considered definitive. A subsequent Chandra observation
of this field, with several times the exposure of this observation, will
result in a longer, more complete list of point sources than that given in
A Chandra/ACIS Study of 30 Doradus II. X-ray Point Sources in the Massive Star
Cluster R136 and Beyond
Townsley L.K., Broos P.S., Feigelson E.D., Garmire G.P., Getman K.V.
<Astron. J., 131, 2164-2184 (2006)>
This table was created by the HEASARC in February 2007 based on the merger of
electronic versions of Tables 1, 2 and 5 from the above reference which were
obtained from the AJ website. It does not include the results from the
spectral analysis of 49 of the X-ray sources having a photometric
significance (signal-to-noise ratio) greater than 2 which are presented in
Tables 3 and 4 of the reference paper.
The HEASARC has combined the main list of primary X-ray sources given in
Table 1 of the above reference with the list of tentative sources given in
Table 2 of the same. In order to clearly identify which table an entry was
taken from, the HEASARC has created a parameter called source_sample which is
set to 'primary' for entries from Table 1 and to 'tentative' for entries from
A running X-ray source number in order of increasing J2000.0
An alternative name for the X-ray source using the '[TBF2006]'
prefix (for Townsley, Broos and Feigelson 2006) and the source number,
as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.
The standard Chandra X-ray source designation using the 'CXOU J'
prefix and the truncated J2000.0 coordinates of the source
The Right Ascension of the X-ray source in the selected equinox. This
was given in J2000.0 decimal degrees to a precision of 10^-6 degrees in the
The Declination of the X-ray source in the selected equinox. This
was given in J2000.0 decimal degrees to a precision of 10^-6 degrees in the
The Galactic Longitude of the X-ray source.
The Galactic Latitude of the X-ray source.
The formal 1-sigma radial positional uncertainty (not
inclusing any systematic uncertainty) based on source counts, as calculated
by acis_extract, in arcseconds. See Section 3.1 of the reference paper for
a more detailed discussion of the total positional uncertainty.
The off-axis angle of the X-ray source, in arcminutes.
The net full-band (0.5 - 8 keV) extracted source counts.
The 1-sigma error in the net full-band source counts,
calculated using Gehrels' (1986, ApJ, 303, 336) equation 7.
The estimated number of background counts in the source
The net hard-band (2 - 8 keV) extracted source counts.
The fraction of the PSF used to extract the source counts.
Sources are extracted with a 90% PSF fraction unless they are in a crowded
region. Thus, a value of less than 90% for the PSF fraction indicates that
the source was crowded and that its properties may be influenced by nearby
The photometric significance (signal-to-noise ratio) of the X-ray
source, i.e., the ratio of the full-band counts to the error in the counts.
This flag parameter is set to '<' if the probability
that the source is a background fluctuation rather than a true point source
is an upper limit rather than an actual value.
The (logarithm of the) probability log(P_B) that the source is
solely a background fluctuation in the full-band counts rather than a true
point source. This represents the authors' primary test of source validity.
As described in Section 2.1 of the reference paper, this quantity
differentiates the 117 sources in the main source catalog (Table 1; those
entries in this HEASARC table with source_sample = 'primary') which have
values of P_B <= 0.003 from the 63 tentative source in Table 2 (those
with source_sample = 'tentative') which have final values of P_B > 0.003.
This parameter contains a set of flags which can note
the presence of various observational anomalies:
g = fractional time that source was on a detector (FRACEXPO) is <0.9
e = source on field edge
p = source piled up
This parameter contains a flag which indicates the
likelihood that the X-ray source is displaying variability, based on a
calculation of the Kolmogorov-Smirnov statistic as first defined in
Feigelson & Lawson (2004, ApJ, 614, 267). Notice that no variability test
was performed for sources with fewer than 4 total full-band
counts, and that no value is reported for sources in chip gaps or on field
edges. The flag values are as follows:
a = no evidence for variability
b = possibly variable
The effective exposure time of the X-ray source, in seconds,
namely the length of time that the source would have to be observed at
the Chandra aimpoint in order to collect the same number of counts as
were actually obtained in the observation as performed.
The estimated background-corrected median energy of the
X-ray source in the full spectral band, in keV (see Section 3.1 of the
reference paper for more details).
The angular separation between the Chandra source and its
counterpart, using a hierarchy of matching catalogs, in arcseconds, as
follows: if a match from Malumuth and Heap (1994, AJ, 107, 1054 = MH94)
was available, then that separation is noted; if there was no MH94 match,
then the separation from the 2MASS counterpart is noted; if neither of
these matches exists, the separation between the ACIS source and its match
from SIMBAD or Vizier is given.
The spectral type of the counterpart star or multiple stellar
system, if known, taken from Breysacher et al. (1999, A&AS, 137, 117 = BAT99),
Crowther & Dessart (1998, MNRAS, 296, 622), or SIMBAD.
The Breysacher et al. (1999) catalog number of the counterpart
star. BAT99 is a catalog of Wolf-Rayet stars in the LMC.
The Parker (1993, AJ, 106, 560 = P93) catalog number of the
counterpart star. P93 is a ground-based UBV photometric study of 30 Dor.
The MH94 catalog number of the counterpart star. MH94 is
a UBV photometric study of 30 Dor performed with the Hubble Space Telescope.
The X-ray source identification from Portegies Zwart et al.
(2002, ApJ, 574, 762 = PPL02)
The Right Ascension (J2000) of the 2MASS counterpart, in
The Declination (J2000) of the 2MASS counterpart, in
This field contains matches to the Chandra X-ray source from other
catalogs, common names for well-known sources, and other notes.
The HEASARC has combined the main list of primary
X-ray sources given in Table 1 of the reference paper with the list of
tentative sources given in Table 2 of the same. In order to clearly identify
which table an entry was taken from, the HEASARC has created this parameter
which is set to 'primary' for entries from Table 1 and to 'tentative' for
entries from Table 2.
The HEASARC Browse object classification based on the value of the
spect_type parameter, when the latter is populated.
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