J/other/JApA/34.393 X-rays obs. in 8 young open star clusters (Bhatt+, 2013)
X-ray observations of eight young open star clusters:
I. Membership and X-ray luminosity.
Bhatt H., Pandey J.C., Singh K.P., Sagar R., Kumar B.
<J. Astrophys. Astron., 34, 393 (2013)>
=2013JApA...34..393B 2013JApA...34..393B
ADC_Keywords: Clusters, open ; X-ray sources ; Infrared sources
Keywords: open clusters and associations: NGC 663, NGC 869, NGC 884, NGC 7380,
Berkeley 86, IC 2602, Trumpler 18, Hogg15 - stars: pre-main sequence -
X-rays: massive stars, intermediate mass stars, low mass stars
Abstract:
We present a detailed investigation of X-ray source contents of eight
young open clusters with ages between 4 to 46Myr using archival X-ray
data from XMM-Newton. The probable cluster memberships of the X-ray
sources have been established on the basis of multi-wavelength
archival data, and samples of 152 pre-main sequence (PMS) low mass
(<2M☉), 36 intermediate mass (2-10M☉) and 16 massive
(>10M☉) stars have been generated. X-ray spectral analyses of
high mass stars reveal the presence of high temperature plasma with
temperature <2keV, and mean LX/Lbol of 10-6.9. In the case of
PMS low mass stars, the plasma temperatures have been found to be in
the range of 0.2keV to 3keV with a median value of ∼1.3keV, with no
significant difference in plasma temperatures during their evolution
from 4 to 46Myr. The X-ray luminosity distributions of the PMS low
mass stars have been found to be similar in the young star clusters
under study. This may suggest a nearly uniform X-ray activity in the
PMS low mass stars of ages ∼4--14Myr. These observed values of
LX)/Lbol_ are found to have a mean value of 10-3.6±0.4, which is
below the X-ray saturation level. The LX/Lbol values for the PMS
low mass stars are well correlated with their bolometric luminosities,
that implies its dependence on the internal structure of the low mass
stars. The difference between the X-ray luminosity distributions of
the intermediate mass stars and the PMS low mass stars has not been
found to be statistically significant. Their LX/Lbol values,
however have been found to be significantly different from each other
with a confidence level greater than 99.999% and the strength of
X-ray activity in the intermediate mass stars is found to be lower
compared to the low mass stars. However, the possibility of X-ray
emission from the intermediate mass stars due to a low mass star in
close proximity of the intermediate mass star can not be ruled out.
Description:
X-ray information of all detected sources in detection procedure
within the field of view of XMM-newton along with their
cross-identification with the 2MASS infrared catalogue (Cutri et al.
2003, Cat. II/246) for eight yong open clusters - NGC 663, NGC 869,
NGC 884, NGC 7380, Berkeley 86, IC 2602, Trumpler 18, Hogg15.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 159 1026 X-ray source detected in eight clusters with
their identification
table4.dat 132 16 X-ray temperatures and luminosities of massive
stars in the eight clusters
table5.dat 131 188 Spectral and timing properties of intermediate
and low mass stars in eight young open clusters
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Cluster Name of the Cluster
16- 18 I3 --- ID [1/208] Identification number of X-ray sources
detected using SAS task edetect_chain,
within the cluster
20- 29 F10.6 deg RAdeg Right ascension of source (J2000)
31- 40 F10.6 deg DEdeg Declination of source (J2000)
42- 45 F4.1 arcsec ePos Error in the estimation of position from
X-ray source detection algorithm
47- 52 F6.1 ct/ks CRpn Count rates in energy band 0.3-7.5keV from
SAS task edetect_chain in PN detector
54- 57 F4.1 ct/ks e_CRpn rms uncertainty on CRpn
60- 65 F6.1 ct/ks CRm1 ? Count rate in energy band 0.3-7.5keV from
SAS task edetect_chain in MOS1 detector
67- 69 F3.1 ct/ks e_CRm1 ? rms uncertainty on CRm1
71- 76 F6.1 ct/ks CRm2 Count rate in energy band 0.3-7.5keV from
SAS task edetect_chain in MOS2 detector
78- 80 F3.1 ct/ks e_CRm2 ? rms uncertainty on CRm2
82- 85 F4.1 arcmin Dist Distance of the source from the center of
the cluster
87 I1 --- N2M Number of multiple identifications of a X-ray
source in 2MASS NIR source catalogue within
10" search radius
89- 92 F4.1 arcsec r2M ? Distance between the positions of the X-ray
source and of its closest NIR within 10"
search radius (1)
94- 99 F6.3 mag Jmag ? Magnitude of the closest X-ray counterpart
in J (1.25µm) band
101-105 F5.3 mag e_Jmag ? rms uncertainty on Jmag
107-112 F6.3 mag Hmag ? Magnitude of the closest X-ray counterpart
in H (1.65µm) band
114-118 F5.3 mag e_Hmag ? rms uncertainty on Hmag
120-125 F6.3 mag Ksmag ? Magnitude of the closest X-ray counterpart
in Ks (2.17µm) band
127-131 F5.3 mag e_Ksmag ? rms uncertainty on Ksmag
133 A1 --- Mm [Y/N] Membership of X-ray source in their
corresponding cluster (2)
135-139 A5 Msun Mass Mass of the source estimated from
color-magnitude diagrams of the clusters for
cluster members ("<2", "2-10", or ">10")
142-159 A18 --- Notes The information of the source from Vizier
database (3)
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Note (1): Only the closest identification of the X-ray source has been reported
in this table.
Note (2): 'Y' represent the cluster member while 'N' represent non-member.
Note (3): The references are:
Sk09 = Skiff (2009, Cat. B/mk)
Cu10 = Currie et al. (2010, Cat. J/AJ/137/3210)
S02 = Slesnick, Hillenbrand & Massey (2002, Cat. J/ApJ/576/880)
S05 = Strom, Wolff & Dror (2005, Cat. J/AJ/129/809)
Pic10 = Pickles & Depagne (2010PASP..122.1437P 2010PASP..122.1437P, Cat. VI/135)
Ogu02 = Ogura, Sugitani & Andrew (2002, Cat. J/AJ/123/2597)
Ike08 = Ikeda et al. (2008, Cat. J/AJ/135/2335)
Glebocki05 = Glebocki & Gnacinski (2005, Cat. III/244)
D'orazi09 = D'Orazi & Randich (2009, Cat. J/A+A/501/553)
Delgado11 = Delgado, Alfaro & Yun (2011, Cat. J/A+A/467/1397)
Kher09 = Kharchenko & Roeser (2009, Cat. I/280)
Fab02 = Fabricius et al. (2002A&A...384..180F 2002A&A...384..180F, Cat. I/276)
Fl10 = probability of the X-ray source for being a star from
Flesch (2010PASA...27..283F 2010PASA...27..283F, Cat. V/134).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 15 A15 ---- Cluster Name of the Cluster
16- 18 I3 ---- ID [1/208] Identification number of X-ray source
20- 32 A13 ---- Name Name of the source
34- 44 A11 ---- SpType MK spectral type of the X-ray source
46 A1 ---- Bin [Y] Y: star is in binary system
48- 51 F4.2 arcsec Off Offset between the position of Massive stars
in 2MASS catalogue and their X-ray
counterparts
52- 55 F4.2 keV kTav ? Average X-ray temperature of massive stars
within young clusters
57- 61 F5.2 keV E_kTav ? Error on kTav (upper value)
63- 66 F4.2 keV e_kTav ? Error on kTav (lower value)
67 A1 --- --- [-]
68- 71 F4.1 keV kTavu ? Upper value of kTav interval when interval
73- 77 F5.2 [10-7W] logLX X-ray luminosity of massive stars within
young clusters (1)
78 A1 --- n_logLX [+] Note on logLX (2)
80-126 A47 --- r_logLX Reference for logLX
128-132 F5.2 ---- logLX/b ?=- Ratio of X-ray to bolometric luminosities
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Note (1): X-ray luminosities of massive stars are either derived in present
study or taken from literature.
Note (2): + when LX has been derived from the X-ray flux estimated from the
count rate conversion in PN detector using the WebPIMMS, i.e.,
Flux=CCF*CountRate.
The values of Count Conversion Factors (in units of erg/s/cm^2) have been
derived for massive stars in PN are 3.606*10-12 for NGC 869 and
7.689*10-12 for Hogg 15, respectively.
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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 A1 --- n_ID [IL] Intermediate mass (2-10M☉) or
Low mass (<2M☉) star
3- 17 A15 ---- Cluster Name of the Cluster
19- 21 I3 ---- ID [1/208] Identification number of X-ray source
23- 32 F10.6 deg RAdeg Right ascension of source (J2000)
34- 43 F10.6 deg DEdeg Declination of source (J2000)
45 A1 --- l_kT Limit flag on kT
46- 50 F5.2 keV kT ? X-ray temperatures of intermediate and
low mass stars
52- 56 F5.2 keV E_kT ? Error on kT (upper value)
58- 61 F4.2 keV e_kT ? Error on kT (upper value)
63 A1 --- l_logEM Limit flag on logEM
64- 68 F5.2 [cm-3] logEM ? Emission measure
70- 73 F4.2 [cm-3] E_logEM ? Error on logEM (upper value)
75- 78 F4.2 [cm-3] e_logEM ? Error on logEM (lower value)
80 A1 --- l_logLX Limit flag on logLX
81- 85 F5.2 [10-7W] logLX ? X-ray luminosities of intermediate and
low mass stars (1)
86 A1 --- u_logLX [?] Uncertainty flag on logLX
88 A1 --- l_logLX/b Limit flag on logLX/b
89- 93 F5.2 --- logLX/b ? Ratio of X-ray to bolometric luminosities
94 A1 --- u_logLX/b [?] Uncertainty flag on logLX/b
96- 99 I4 s Tsize ? Time Bin size for timing analysis
101-104 F4.2 ---- Fvar ? Fractional root mean square variability
amplitude
106-109 F4.2 ---- e_Fvar ? rms uncertainty on Fvar
111-131 A21 --- Note Notes
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Note (1): X-ray luminosities are derived from either spectral fitting using
C-statistics or derived from conversion of count rates into X-ray fluxes
using count conversion factors (CCFs).
X-ray flux derived from spectral fitting are converted into luminosities
using the distance to their corresponding clusters.
The spectral parameters are not derived for the stars with poor count
statistics and their unabsorbed X-ray fluxes have been estimated by their
count rates in EPIC detector using CCFs (WebPIMMS), i.e., Flux=CCF*CountRates.
The values of CCFs (in units of erg/s/cm2) are derived for PN and MOS
detectors.
* For Intermediate mass stars:
3.926*10-12 and 1.247*10-11 for NGC 869 at 2.07keV ;
3.528*10-12 and 1.181*10-11 for NGC 884 at 1.30keV ;
4.799*10-12 and 1.433*10^-11 for NGC 7380 at 2.38keV ;
1.835*10-11 and 6.740*10^-11 for Hogg 15 at 0.29keV;
* For Low mass stars:
4.937*10-12 and 1.847*10-11 for NGC 663 at 0.71keV;
3.926*10-12 and 1.292*10-11 for NGC 869 at 2.05keV;
3.610*10-12 and 1.206*10-11 for NGC 884 at 1.59keV;
4.931*10-12 and 1.460*10-11 for NGC 7380 at 2.80keV ;
6.054*10-12 and 1.749*10-11 for Berkeley 86 at 1.87keV;
7.689*10-11 and 2.290*10-11 for Hogg 15 at 0.97keV ;
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Acknowledgements:
Himali Bhatt, mshimali(at)gmail.com
(End) Himali Bhatt [BARC, Mumbai INDIA], Patricia Vannier [CDS] 29-Jan-2014