J/ApJ/608/781 NGC 6530 Chandra X-ray catalog (Damiani+, 2004)
A deep Chandra X-ray observation of the rich young cluster NGC 6530.
I. The X-ray source catalog and the cluster population.
Damiani F., Flaccomio E., Micela G., Sciortino S., Harnden F.R.Jr,
Murray S.S.
<Astrophys. J., 608, 781-796 (2004)>
=2004ApJ...608..781D 2004ApJ...608..781D
ADC_Keywords: X-ray sources ; Clusters, open ; Stars, pre-main sequence
Keywords: open clusters and associations: individual (NGC 6530) -
stars: coronae - stars: pre-main-sequence - X-rays: stars
Abstract:
In a deep 60ks Chandra ACIS X-ray observation of the very young
cluster NGC 6530, we detect 884 X-ray point sources and argue that a
very large fraction of them (90%-95%) must be pre-main-sequence (PMS)
cluster members, mostly of low masses. This is a significant
enlargement of the known NGC 6530 stellar population with respect to
previous optical studies, including Hα surveys. We identify 220
X-ray sources with catalogued stars down to V=17, while most
unidentified sources have fainter counterparts. Moreover, we find an
infrared counterpart in the 2MASS (II/246) catalog for 731 X-ray
sources. The optically identified cluster X-ray sources are found in a
band in the H-R diagram above the main sequence, in the locus of
0.5-1.5Myr PMS stars, with masses down to 0.5-1.5M☉.
Description:
NGC 6530 was observed for 60ks with the Chandra ACIS-I CCD detector
on 2001 June 18-19 as part of the GTO program.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 141 901 NGC 6530 X-Ray Source Properties and Identifications
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/AJ/120/333 : UBVRI and Hα in NGC 6530 (Sung+, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [DFM2004] X-ray running number
5- 6 I2 h RAh Hour of Right Ascension (J2000.0)
8- 9 I2 min RAm Minute of Right Ascension (J2000.0)
11- 15 F5.2 s RAs Second of Right Ascension (J2000.0)
17 A1 --- DE- Sign of the Declination (J2000.0)
18- 19 I2 deg DEd Degree of Declination (J2000.0)
21- 22 I2 arcmin DEm Arcminute of Declination (J2000.0)
24- 27 F4.1 arcsec DEs Arcsecond of Declination (J2000.0)
29- 32 F4.2 arcsec e_Pos Position error
34- 40 F7.3 ct/ks CRate Count rate
42- 46 F5.3 ct/ks e_CRate Uncertainty in CRate
48- 53 F6.3 --- PK-S Kolmogorov-Smirnov test probability X-ray
source is constant
55- 60 F6.3 --- HR1 ? First hardness ratio (1)
62- 67 F6.3 --- HR2 Second hardness ratio (2)
69- 71 I3 --- SCB ? Sung et al. (2000, Cat. J/AJ/120/333)
number (Cl* NGC 6530 SCB NNNN in Simbad)
73- 77 F5.2 arcsec OffX-O ? X-ray and SCB optical positions offset
79- 84 F6.3 mag Vmag ? SCB V band magnitude
86- 91 F6.3 mag V-I ? SCB (V-I) color
93- 97 F5.3 mag B-V ? SCB (B-V) color
99-114 A16 --- 2MASS The 2MASS (Cat. II/246) designation
116-119 F4.2 arcsec OffX-IR ? X-ray and 2MASS positions offset
121-126 F6.3 mag Jmag ? 2MASS J band magnitude
128-133 F6.3 mag Hmag ? 2MASS H band magnitude
135-140 F6.3 mag Kmag ? 2MASS K band magnitude
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Note (1): Defined as (H-S)/(H+S) where H and S are the source counts in two
energy bands, here chosen as 0.75-1.5keV and 0.3-0.75keV.
Note (2): Defined as (H-S)/(H+S) where H and S are the source counts in two
energy bands, here chosen as 1.5-8.0keV and 0.75-1.5keV.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 14-Jun-2005