J/A+A/564/A120 Chandra X-ray observation of Gum 31 (Preibisch+, 2014)
Chandra X-ray observation of the HII region Gum 31 in the Carina nebula complex.
Preibisch T., Mehlhorn M., Townsley L., Broos P., Ratzka T.
<Astron. Astrophys. 564, A120 (2014)>
=2014A&A...564A.120P 2014A&A...564A.120P
ADC_Keywords: H II regions ; X-ray sources
Keywords: stars: formation - stars: pre-main sequence - X-ray: stars -
open clusters and associations: NGC 3324 -
open clusters and associations: NGC 3372
Abstract:
Gum 31 is a prominent, but still rather poorly studied HII region
around the stellar cluster NGC 3324 at the northwestern periphery of
the Carina nebula complex.
Our aim was to reveal and characterize the young stellar population in
Gum 31. An X-ray survey is the only efficient way to identify young
stars in this region with extremely high galactic field-star
contamination that can avoid the strong biases of infrared excess
selected samples of disk-bearing young stars.
We used the Chandra observatory to perform a deep (70ks) X-ray
observation of the Gum 31 region and detected 679 X-ray point sources.
This extends and complements the X-ray survey of the central Carina
nebula regions performed in the Chandra Carina Complex Project (CCCP).
Using deep near-infrared images from our recent VISTA survey of the
Carina nebula complex, our comprehensive Spitzer point-source catalog,
and optical archive data, we identify counterparts for 75% of these
X-ray sources.
Description:
Basic properties and near- and mid-infrared photometry of the X-ray
sources in Gum 31.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 679 Basic properties of the Chandra X-ray sources
in the Gum 31 region
table3.dat 154 679 Near- and mid-infrared photometry of the
X-ray sources in Gum 31
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/679] X-ray catalog sequence number,
sorted by RA
5- 22 A18 --- Name IAU designation of the X-ray source
(HHMMSS.ss+DDMMSS.s, J2000)
24- 33 F10.6 deg RAdeg Right ascension (J2000)
35- 44 F10.6 deg DEdeg Declination (J2000)
46- 48 F3.1 arcsec ePos [0/1.4] Position error (1)
50- 54 F5.2 arcmin theta Off-axis angle θ
56- 60 F5.1 ct Ctnet Net counts in the total energy band (0.5-8keV)
62- 65 F4.1 ct e_Ctnet 1-σ errors on net counts
67- 70 F4.1 ct Bt Background counts expected in the source
extraction region (total band)
72- 76 F5.1 ct CHnet Net counts in the hard energy band (2-8keV)
78- 81 F4.2 --- fPSF [0/1] Fraction of the PSF (at 1.497keV)
enclosed within the extraction region (2)
83- 86 F4.1 --- Signi [1/30] Photometric significance (3)
88 A1 --- l_logPB Limit flag on logPB
89- 92 F4.1 --- logPB [-5/-2] Logarithmic probability PB that the
extracted counts (total band) are solely
from background (4)
94- 97 A4 --- f_Seq [g.] Source anomalies (5)
99 A1 --- Var [abc] Variability characterization based on
K-S statistic (total band) from the single
ObsId showing the most variability (6)
101-103 F3.1 keV Emed Background-corrected median photon energy
(total band)
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Note (1): Estimated standard deviation of the random component of the position
error, sqrt(σx2+σy2). The single-axis position errors,
σx and σy, are estimated from the single-axis standard
deviations of the PSF inside the extraction region and the number of counts
extracted.
Note (2): A reduced PSF fraction (significantly below 90%) may indicate
that the source is in a crowded region.
Note (3): computed as net counts divided by the upper error on net count.
Note (4): Some sources have PB values above the 1% threshold that defines
the catalog because local background estimates can rise during the final
extraction iteration after sources are removed from the catalog.
Note (5): Source anomalies as follows:
g = fractional time that source was on a detector (FRACEXPO from mkarf)
is <0.9
p = source piled up
s = source on readout streak
a = photometry and spectrum contain >10% afterglow events
Note (6): Variability characterization as follows:
a = no evidence for variability (0.05<P_KS)
b = possibly variable (0.005<PKS<0.05)
c = definitely variable (PKS<0.005)
= no value is reported for sources with fewer than four counts or for
sources in chip gaps or on field edges
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq X-ray catalog sequence number, sorted by RA
5- 22 A18 --- Name IAU designation of the X-ray source
(HHMMSS.ss+DDMMSS.s, J2000)
24- 41 A18 --- VISTA IAU designation of the corresponding VISTA
source (HHMMSS.ss+DDMMSS.s, J2000)
43- 47 F5.2 mag Jmag ?=-9.99 Near-infrared photometry in the J band
49- 53 F5.2 mag Hmag ?=-9.99 Near-infrared photometry in the H band
55- 59 F5.2 mag Ksmag ?=-9.99 Near-infrared photometry in the Ks band
61- 67 F7.1 --- SNRJ ?=0 Signal-to-noise ratio of the J band
flux measurement
69- 75 F7.1 --- SNRH ?=0 Signal-to-noise ratio of the H band
flux measurement
77- 82 F6.1 --- SNRKs ?=0 Signal-to-noise ratio of the Ks band
flux measurement
84 I1 --- Src [1/2]?=0 Flag indicating the source of the
JHK photometry: 1=VISTA, 2=2MASS
86-103 A18 --- Spitzer IAU designation of the corresponding Spitzer
source (HHMMSS.ss+DDMMSS.s, J2000)
105-109 F5.2 mag [3.4] ?=-9.99 Mid-infrared photometry in the Spitzer
IRAC 3.4µm (1) band
111-115 F5.2 mag [4.5] ?=-9.99 Mid-infrared photometry in the Spitzer
IRAC 4.5µm (2) band
117-121 F5.2 mag [5.8] ?=-9.99 Mid-infrared photometry in the Spitzer
IRAC 5.8µm (3) band
123-127 F5.2 mag [8.0] ?=-9.99 Mid-infrared photometry in the Spitzer
IRAC 8.0µm (4) band
129-135 F7.1 --- SNR1 ?=0 Signal-to-noise ratio of IRAC-1 flux
137-142 F6.1 --- SNR2 ?=0 Signal-to-noise ratio of IRAC-2 flux
144-148 F5.1 --- SNR3 ?=0 Signal-to-noise ratio of IRAC-3 flux
150-154 F5.1 --- SNR4 ?=0 Signal-to-noise ratio of IRAC-4 flux
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Acknowledgements:
Thomas Preibisch, preibisch(at)usm.uni-muenchen.de
(End) Patricia Vannier [CDS] 19-Mar-2014