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*J/A+A/596/A82* X-ray study of the young cluster NGC6231 (Damiani+, 2016)
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A Chandra X-ray study of the young star cluster NGC 6231:
low-mass population and initial mass function.
Damiani F., Micela G., Sciortino S.
=2016A&A...596A..82D (SIMBAD/NED BibCode)
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*ADC_Keywords*: Clusters, open - Stars, pre-main sequence - X-ray sources
*Keywords*: stars: pre-main-sequence -
open clusters and associations: individual (NGC 6231) -
stars: coronae - stars: luminosity function, mass function -
X-rays: stars
*Abstract*:
NGC 6231 is a massive young star cluster, near the center of the Sco
OB1 association. While its OB members are well studied, its low-mass
population has received little attention. We present high-spatial
resolution Chandra ACIS-I X-ray data, where we detect 1613 point X-ray
sources.
Our main aim is to clarify global properties of NGC 6231 down to low
masses through a detailed membership assessment, and to study the
cluster stars' spatial distribution, the origin of their X-ray
emission, the cluster age and formation history, and initial mass
function.
We use X-ray data, complemented by optical and IR data, to establish
cluster membership. The spatial distribution of different stellar
subgroups also provides highly significant constraints on cluster
membership, as does the distribution of X-ray hardness. We perform
spectral modelling of group-stacked X-ray source spectra.
*Description*:
X-ray properties of sources in the Chandra observations of NGC6231
(columns 1-13), and their identifications in the catalogs of Sung,
Sana and Bessell (2013, Cat. J/AJ/145/37 ; SSB), VPHAS+ (Drew et al.,
2014, Cat. J/MNRAS/440/2036 ), and 2MASS (Cat. II/246 ) (columns 14-25).
The last five columns refer to membership, H? or IR excess, mass
and luminosity. Rows 1-1613 list X-ray candidate members, while rows
1614-1888 list additional candidate members from H? or IR excess.
*File Summary*:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb.dat <#sRM2.1> 229 1888 X-ray, optical, and IR data for Chandra sources
in NGC6231
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*See also*:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/AJ/145/37 : UBVI and H? CCD photometry of NGC 6231 (Sung+, 2013)
J/MNRAS/440/2036 : VPHAS+ survey synthetic colours (Drew+, 2014)
J/AJ/115/734 : NGC 6231 UBVRI and H? photometry (Sung+ 1998)
J/A+AS/137/233 : UBVI imaging photometry of NGC 6231 (Baume+, 1999)
J/MNRAS/372/661 : XMM view of NGC 6231: OB stars (Sana+, 2006)
J/A+A/454/1047 : XMM view of NGC 6231 open cluster (Sana+, 2006)
J/MNRAS/386/447 : RV catalogue of O-type stars in NGC 6231 (Sana+, 2008)
*Byte-by-byte Description of file*: tableb.dat <#sRM-F.47>
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq Star number
6- 9 A4 --- --- [CXOU]
11- 26 A16 --- CXOU IAU X-ray source designation
(JHHMMSS.s+DDMMSS)
28- 36 F9.5 deg RAdeg ? Right ascension (J2000.0)
38- 46 F9.5 deg DEdeg ? Declination (J2000.0)
48- 51 F4.2 arcsec e_Pos ? Position error
53- 58 F6.1 ct CT ? Total X-ray detected counts
60- 66 F7.3 ct/s CR ? X-ray count rate
68- 72 F5.3 ct/s e_CR ? Error on X-ray count rate
74- 78 F5.1 % PK-S ? Probability of not being constant
80- 84 F5.2 --- HR1 ? Hardness ratio 1:
bands [0.3-1.2], [1.2-2.2]keV
86- 90 F5.2 --- HR2 ? Hardness ratio 2:
bands [1.2-2.2], [2.2-8.0]keV
92- 96 F5.2 [10-7W] logLX ? log X-ray luminosity
98-102 F5.2 [10-7W] logLXq ? log quiescent X-ray luminosity
104-108 I5 --- SBB ? Identifier in SBB (Sung et al.,
2013, Cat. J/AJ/145/37 )
110-115 F6.3 mag Vmag ? SSB V magnitude
117-122 F6.3 mag V-I ? SSB V-I Color
124-129 F6.3 mag HalphaS ? SSB H-alpha index
131-148 A18 --- VPHAS VPHAS+ identifier (JHHMMSS.s+DDMMSS.s)
(Drew et al., DR2, 2016, Cat. II/341 )
150-155 F6.3 mag rmag ? VPHAS+ r magnitude
157-162 F6.3 mag imag ? VPHAS+ i magnitude
164-169 F6.3 mag HalphaV ? VPHAS+ H-alpha magnitude
171-188 A18 --- 2MASS 2MASS identifier (JHHMMSSss+DDMMSSs)
190-195 F6.3 mag Jmag ? 2MASS J magnitude
(Cutri et al., 2003, Cat. II/246 )
197-202 F6.3 mag Hmag ? 2MASS H magnitude
204-209 F6.3 mag Kmag ? 2MASS K magnitude
211 I1 --- Group ? Group from color-magnitude diagram
213 A1 --- IRexcess [Y] IR-excess flag
215 A1 --- Haexcess [Y] H-alpha-excess flag
217-222 F6.3 Msun Mass ? Derived Star mass
224-229 F6.3 [Lsun] logLbol ? Star bolometric luminosity
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*Acknowledgements*:
Francesco Damiani, damiani(at)astropa.inaf.it
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*(End)* Francesco Damiani [INAF-OAPA], Patricia Vannier [CDS] 16-Sep-2016
/The document above follows the rules of the Standard Description for
Astronomical Catalogues ; from
this documentation it is possible to generate *f77* program to load
files into arrays
or line by line
/
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