J/AJ/138/227 Stellar clusters in NGC 6334 complex (Feigelson+, 2009)
Stellar clusters in the NGC 6334 star-forming complex.
Feigelson E.D., Martin A.L., McNeill C.J., Broos P.S., Garmire G.P.
<Astron. J., 138, 227-239 (2009)>
=2009AJ....138..227F 2009AJ....138..227F
ADC_Keywords: Molecular clouds ; H II regions ; Stars, pre-main sequence ;
X-ray sources
Keywords: ISM: clouds - ISM: individual (NGC 6334) - stars: early-type -
stars: formation - stars: pre-main sequence - X-rays: stars
Abstract:
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. We analyze here 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.
Description:
The X-ray observations discussed here were previously presented by
Ezoe et al. (2006ApJ...638..860E 2006ApJ...638..860E). NGC 6334 was observed in two
overlapping exposures of the Imaging Array of the Advanced CCD Imaging
Spectrometer (ACIS-I), each 40ks in duration and covering a ∼17'x17'
field of view.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 143 1607 Chandra catalog of X-ray sources in NGC 6334
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-)
J/ApJS/69/99 : NGC6334 centers of star formation JHK photometry (Straw+ 1989)
J/A+A/316/102 : JHK Photometry in NGC 6334 (Tapia+, 1996)
J/A+A/357/1020 : JHK photometry in NGC 6334 IV (Persi+, 2000)
J/ApJ/668/906 : Massive clumps in NGC 6334 (Munoz+, 2007)
J/AJ/136/2083 : Clumps in NGC 6334 from 450/850um obs. (Matthews+, 2008)
J/A+A/515/A55 : NGC 6334-NGC 6357 complex (Russeil+, 2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/1607] Running sequence number; sorted by RA
6- 23 A18 --- CXOU IAU designation (HHMMSS.ss+DDMMSS.s, CXOU J+)
25- 34 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
36- 45 F10.6 deg DEdeg Declination in decimal degrees (J2000)
47- 49 F3.1 arcsec ePos ? Estimated standard deviation of random
component of position error (1)
51- 54 F4.1 arcmin Offax ? Off-axis angle
56- 61 F6.1 ct CtT ? Net extracted total 0.5-8keV band counts
63- 66 F4.1 ct e_CtT ? Average upper and lower 1σ errors on Ct
68- 72 F5.1 ct BtT ? Expected background total 0.5-8keV band
counts (2)
74- 79 F6.1 ct CtH ? Net extracted hard 2-8keV band counts
81- 84 F4.2 --- PSF ? Fraction of PSF at 1.5keV enclosed in
extraction region (3)
86 A1 --- l_logPb Limit flag on logPb
87- 91 F5.1 [-] logPb Log probability source arises from local
background fluctuations (4)
93- 95 F3.1 keV Emed ? Background-corrected median photon energy;
total band
97 A1 --- l_Ksmag Limit flag on Ksmag (5)
99-103 F5.2 mag Ksmag ? 2MASS/Ks band magnitude (6)
104 A1 --- u_Ksmag [:] Indicates photometric confusion (7)
106-143 A38 --- PosID Possible counterparts (8)
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Note (1): (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): in extraction region.
Note (3): A reduced PSF fraction (significantly below 90%) may indicate
that the source is in a crowded region.
Note (4): Based on Poisson statistics.
Note (5): Indicates source was detected in the J or H bands but not the K band.
Note (6): From 2MASS-Point Source Catalogue (Cat. II/246) within 1 arcsec
of the X-ray position.
Note (7): By a nearby star or nebular emission, or photometric accuracy
worse than ±0.2mag.
Note (8): Within 3 arcsec of the X-ray source in the SIMBAD database of
published objects. FIR-V sources are from Straw & Hyland
(1989ApJ...340..318S 1989ApJ...340..318S), TPR stars are from Tapia et al. (1996, Cat.
J/A+A/316/102), and other designations are discussed in the text.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 15-Nov-2011