J/A+A/477/147 X-ray sources in Westerlund 1 (Clark+, 2008)
Unveiling the X-ray point source population of the Young Massive Cluster
Westerlund 1.
Clark J.S., Muno M.P., Negueruela I., Dougherty S.M., Crowther P.A.,
Goodwin S.P., De Grijs R.
<Astron. Astrophys., 477, 147-163 (2008)>
=2008A&A...477..147C 2008A&A...477..147C
ADC_Keywords: Clusters, open ; X-ray sources ; Photometry
Keywords: stars: evolution - X rays: stars -
open clusters and associations: individual: Westerlund 1
Abstract:
We investigate the nature of the X-ray point source population within
the Young Massive Cluster Westerlund 1.
Chandra observations of 18 ks and 42 ks were used to determine the
X-ray properties of emitters within Wd 1, while a comprehensive
multiwavelength dataset was employed to constrain their nature.
We find X-ray emission from a multitude of different stellar sources
within Wd 1, including both evolved high mass and low mass pre-MS
stars.
Description:
Wd 1 (l=339.5, b=-0.4) was observed with the Chandra X-ray Observatory
Advanced CCD Spectrometer Spectroscopic array on 2005 May 22 for 18ks
(sequence 6283) and 2005 June 20 for 42ks (sequence 5411).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 97 241 Catalogue of the properties of the 241 X-ray point
sources detected in the 2 epochs of observations
table3.dat 98 53 Summary of the X-ray and optical properties of the
X-ray point sources with high mass stellar
counterparts
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
J/A+AS/127/423 : VI photometry of Westerlund 1 and 2 (Piatti+ 1998)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- [CMN2008] X-ray Identifier (HHMMSS.s+DDMMSS)
17- 25 F9.5 deg RAdeg Right ascension in decimal degrees (J2000)
27- 35 F9.5 deg DEdeg Declination in decimal degrees (J2000)
37- 40 F4.1 arcmin Offset Angular offset from the aim point of the
observation
42- 45 F4.1 arcsec e_Pos Positional uncertainty
47- 50 F4.1 ks LiveTime Detector live time
52- 57 F6.1 ct Counts Net counts in the 0.5-8.0keV band
59- 62 F4.1 ct E_Counts Error on net counts (upper limit)
64- 67 F4.1 ct e_Counts Error on net counts (lower limit)
69- 73 F5.2 --- HR Hardness ratio (G1)
75- 78 F4.2 --- E_HR ?=- Error on hardness ratio (upper limit)
80- 83 F4.2 --- e_HR ?=- Error on hardness ratio (lower limit)
85- 89 F5.1 10-7ph/cm2/s FX X-ray flux in the 0.5-8.0keV band
91- 92 A2 --- Var [sl ] Source variability on (s)hort or
(l)ong timescales
94- 97 A4 --- NCP Counterpart flag (2)
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Note (2): Indicates whether an X-ray source has an optical or near-IR
counterpart. The source catalogues utilised are
1 = Clark et al. (2005A&A...434..949C 2005A&A...434..949C)
2 = Piatti et al. (1998, Cat. J/A+AS/127/423
3 = the 2MASS catalogue (Cutri et al., 2003, Cat. II/246)
4 = the USNO-B1.0 survey (Monet et al., 2003, cat. I/284)
Designations for optical or near-IR counterparts for sources within
the 5'x5' field centred on Wd1 are presented in table3.dat file.
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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- 15 A15 --- [CMN2008] X-ray Identifier (HHMMSS.s+DDMMSS)
17 A1 --- n_[CMN2008] [i] Note on Name (1)
18- 22 F5.1 ct Counts Net counts in the 0.5-8.0keV band
24- 27 F4.1 ct E_Counts Error on net counts (upper limit)
29- 32 F4.1 ct e_Counts Error on net counts (lower limit)
34- 38 F5.2 --- HR Hardness ratio (G1)
40- 43 F4.2 --- E_HR ?=- Error on Harness ratio (upper limit)
45- 48 F4.2 --- e_HR ?=- Error on Harness ratio (lower limit)
50- 51 I2 --- Seq ?=- Number of the source in the finding chart
(Fig. 6) (2)
53- 58 A6 --- OptID Optical designation (3)
61- 64 F4.1 mag Bmag ?=- B magnitude
66- 70 F5.2 mag Vmag ?=- V magnitude
72- 76 F5.2 mag Rmag ?=- R magnitude
78- 82 F5.2 mag Imag ?=- I magnitude
84- 96 A13 --- SpType MK spectral type (4)
98 A1 --- Var [AEP] Variability flag (5)
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Note (1): i: 164706.2-455048 was found to be variable in these observations
Note (2): We strongly advise that these numbers should not form the basis
for a new naming convention.
Note (3): Sources with 2MASS or Piatti et al. (1998, Cat. J/A+AS/127/423,
Cl* Westerlund 1 PBC NNN in Simbad) designations are indicated.
Note (4): For those sources for which no entry is given but for which
photometric data are available, we predict a spectral classification
earlier than B0.5Ia (Sect. A.3).
Note (5): Stars which Bonanos (2007AJ....133.2696B 2007AJ....133.2696B) find to be as follows:
E = Eclipsing photometric variable
P = Periodic photometric variable
A = Aperiodic photometric variables
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Global notes:
Note (G1): HR=(H-S)(H+S) where S is the number of counts in the 0.5-2.0keV
and H number of counts in the 2.0-8.0keV
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 15-Feb-2008