J/AJ/135/693 X-ray and IR sources in RCW 108 (Wolk+, 2008)
X-ray and IR point source identification and characteristics in the embedded,
massive star-forming region RCW 108.
Wolk S.J., Spitzbart B.D., Bourke T.L., Gutermuth R.A., Vigil M.,
Comeron F.
<Astron. J., 135, 693-721 (2008)>
=2008AJ....135..693W 2008AJ....135..693W
ADC_Keywords: H II regions ; Photometry, infrared ; X-ray sources
Keywords: H II regions - ISM: individual (RCW 108) - stars: formation -
X-rays: stars
Abstract:
We report on the results of an approximately 90ks Chandra observation
of a complex region that hosts multiple sites of recent and active
star formation in ARA OB1a. The field is centered on the embedded
cluster RCW 108-IR and includes a large portion of the open cluster
NGC 6193. We detect over 420 X-ray sources in the field and combined
these data with deep near-IR, Spitzer/IRAC and Midcourse Space
Experiment (MSX) mid-IR data. We find about 360 of the X-ray sources
have near-IR counterparts. We divide the region into five parts based
on the X-ray point source characteristics and extended 8um emission.
The most clearly defined regions are the central region, identified by
embedded sources with high luminosities in both the near-IR and X-ray
as well as high X-ray temperatures (∼3keV), and the eastern region,
identified by low extinction and ∼1keV X-ray temperatures. The cluster
members range in X-ray luminosity from 1029 to 1033erg/s. Over 18% of
the cluster members with over 100 counts exhibit flares. All sources
with over 350 counts are variable. Overall about 10% (16% in RCW
108-IR) appear to have optically thick disks as derived from their
position in the (J-H), (H-K) diagram. The disk fraction becomes much
higher when IRAC data are employed. We fit the bulk of the X-ray
spectra as absorbed Raymond-Smith-type plasmas, and find that the
column to the RCW 108-IR members varies from 1021 to 1023cm-2. We
find that the field contains 41 candidate O or B stars, and estimate
that the total number of pre-main-sequence stars in the field is about
1600±200.
Description:
The field was observed by Chandra on 2004 October 25, the aimpoint was
at 16:39:58.7, -48:51:54.4 (J2000.0). The MSX obtained observations
of RCW 108-IR and its surroundings at 8.3, 12.1, 14.7, and 21.3um as
part of its Galactic plane survey. In the near-IR we use J, H, and
Ks photometry obtain from 2MASS project and from a deep pointed
observation of RCW 108-IR. RCW 108-IR was observed with the Infrared
Array Camera (IRAC) on board the Spitzer Space Telescope in 2005
September (PID 112). Observations at 1.2mm were obtained in 2002
September and 2002 November with the 37-channel hexagonal bolometer
array SIMBA at the SEST, located in La Silla, Chile.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 73 337 Bright X-ray sources detected in the RCW 108 field
table2.dat 71 87 Faint X-ray sources detected in the RCW 108 field
table5.dat 58 336 Quartile values of X-ray sources
table7.dat 64 337 One temperature spectral fits
table10.dat 115 367 Near-IR observations of X-ray sources
table11.dat 75 235 IRAC detections of X-ray sources in the RCW 108 field
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See also:
J/A+A/473/149 : Sources in IRAS 16362-4845 cluster photometry (Comeron+, 2007)
J/AJ/132/1100 : X-ray and IR sources in RCW 38 (Wolk+, 2006)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Src Running source number ([WSB2008] in Simbad)
5- 21 A17 --- CXOWSB Official IAU style identification
(HHMMSS.s+DDMMSS.s)
23- 24 I2 h RAh X-ray centroid hour of Right Ascension (J2000)
26- 27 I2 min RAm X-ray centroid minute of Right Ascension (J2000)
29- 34 F6.3 s RAs X-ray centroid second of Right Ascension (J2000)
36 A1 --- DE- X-ray centroid sign of the Declination (J2000)
37- 38 I2 deg DEd X-ray centroid degree of Declination (J2000)
40- 41 I2 arcmin DEm X-ray centroid arcminute of Declination (J2000)
43- 47 F5.2 arcsec DEs X-ray centroid arcsecond of Declination (J2000)
49- 53 F5.1 arcsec Off Off axis angle
55- 60 F6.1 ct Rcts ? Raw counts (only for table1)
62- 64 F3.1 ct Ssig ? Source signal (only for table2)
66- 71 F6.1 ct Ncts Net counts
73 I1 --- Var [1/7]? Number of Bayesian block >95% confidence
required to describe the lightcurve (table1) (1)
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Note (1): Any number >1 indicates variability at 95% confidence.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Loc1 Location (Inner/East/West/North/South)
7- 9 I3 --- Src Running source number
11- 15 F5.3 --- Q25 ? The bottom (25%) quartile value
17- 21 F5.3 --- e_Q25 ? Error in Q25
23- 27 F5.3 --- m ? The median quartile (=Q50)
29- 33 F5.3 --- e_m ? Error in m
35- 39 F5.3 --- Q75 ? The top (75%) quartile value
41- 45 F5.3 --- e_Q75 ? Error in Q75
47- 52 F6.3 [-] log(m/(1-m)) ? Log of the m/(1-m) value
54- 58 F5.3 --- 3*Q25/Q75 ? Three times Q25 divided by Q75
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Loc Location (RCW 108-IR/East/West/North/South)
12- 14 I3 --- Src Running source number
16- 19 F4.2 --- chi2 The χ2 value (1)
21- 25 F5.2 10+22/cm2 NH Model hydrogen column density
27- 30 F4.2 10+22/cm2 e_NH ? Error in NH
32 A1 --- l_kT Limit flag on kT
34- 38 F5.2 keV kT Model temperature
40- 44 F5.2 keV e_kT ? Error in kT
46- 51 F6.2 [mW/m2] AFlux Absorbed flux
53- 58 F6.2 [mW/m2] UFlux Unabsorbed flux
60- 64 F5.2 [10-7W] LogLx Log of X-ray luminosity
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Note (1): Per degree of freedom. χ2/d.o.f is included for
completeness. These models were calculated with C statistics, it is
unclear how χ2/d.o.f relates to goodness of fit. The formal
errors are unbiased however. See text.
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Loc Location (RCW 108-IR/East/West/North/South)
12- 14 I3 --- Src Running source number
16 A1 --- f_Src [a] double source (1)
18- 19 I2 h RAh IR source hour of Right Ascension (J2000)
21- 22 I2 min RAm IR source minute of Right Ascension (J2000)
24- 28 F5.2 s RAs IR source second of Right Ascension (J2000)
30 A1 --- DE- IR source sign of the Declination (J2000)
31- 32 I2 deg DEd IR source degree of Declination (J2000)
34- 35 I2 arcmin DEm IR source arcminute of Declination (J2000)
37- 40 F4.1 arcsec DEs IR source arcsecond of Declination (J2000)
42- 46 F5.3 arcsec Offset ? Offset from X-ray centroid position
48- 52 F5.1 arcsec Off Off axis angle
54- 58 F5.2 mag Jmag ? The J band magnitude
60- 65 F6.4 mag e_Jmag ? Error in Jmag
67- 71 F5.2 mag Hmag ? The H band magnitude
73- 78 F6.4 mag e_Hmag ? Error in Hmag
80- 85 F6.3 mag Ksmag ? The KS band magnitude
87- 92 F6.4 mag e_Ksmag ? Error in Kmag
94- 98 F5.2 mag Qmag ? Infrared excess, reddening free quantity (2)
100-104 F5.2 mag AV ? The V band extinction
106-111 A6 --- Model Stellar model used (Disk, M star or
HMS = Higher mass star)
113-115 A3 --- Flag Source flag (4)
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Note (1): VLT adaptive optics data indicate this source is a double.
Note (2): Using the reddening free quantity: Q=(J-H)-1.70*(H-KS).
Note (4): Sources flag as follows:
VLT = data are from the Very Large Telescope, reduction discussed in
Comeron & Schneider (2007, Cat. J/A+A/473/149);
NTT = data are from New Technology Telescope, reduction discussed in
Comeron et al. (2005A&A...433..955C 2005A&A...433..955C);
The codes AAA, UAB, UAU, AAU, etc. represent the 2MASS (Cat. II/246)
photometry quality codes for the JHK channels:
A = error<10.9%,
B = error<15.6%,
E = This category includes detections where the goodness-of-fit
quality of the profile-fit photometry was very poor
U = upper limit
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Byte-by-byte Description of file: table11.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Loc Location (RCW 108-IR/East/West/North/South)
12- 14 I3 --- Src Running source number
16- 20 F5.3 arcsec Offset Offset from X-ray centroid position
22- 27 A6 arcsec Off Off axis angle
29- 33 F5.2 mag 3.6mag ? Spitzer/IRAC 3.6 micron band magnitude
35- 39 F5.2 mag 4.5mag ? Spitzer/IRAC 4.5 micron band magnitude
41- 45 F5.2 mag 5.8mag ? Spitzer/IRAC 5.8 micron band magnitude
47- 51 F5.2 mag 8.0mag ? Spitzer/IRAC 8.0 micron band magnitude
53- 56 F4.2 mag e_3.6mag ? Error in 3.6mag
58- 61 F4.2 mag e_4.5mag ? Error in 4.5mag
63- 66 F4.2 mag e_5.8mag ? Error in 5.8mag
68- 71 F4.2 mag e_8.0mag ? Error in 8.0mag
73- 75 A3 --- Class IR evolution class (I=protostars, II=PMS with
disk, III=diskless PMS star)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 18-Jun-2010