J/A+A/474/495 X-ray flares from Cygnus OB2 young stars (Albacete Colombo+, 2007)
X-ray flaring from the young stars in Cygnus OB2.
Albacete Colombo J.F., Caramazza M., Flaccomio E., Micela G., Sciortino S.
<Astron. Astrophys., 474, 495-504 (2007)>
=2007A&A...474..495A 2007A&A...474..495A
ADC_Keywords: Associations, stellar ; Stars, pre-main sequence ; X-ray sources ;
Keywords: stars: activity - stars: corona - stars: low-mass, brown dwarfs -
X-rays: stars
Abstract:
We characterize individual and ensemble properties of X-ray flares
from stars in the Cygnus OB2 and ONC star-forming regions.
We analyzed X-ray light-curves of 1003 Cygnus OB2 sources observed
with Chandra for 100ks and of 1616 ONC sources detected in the
"Chandra Orion Ultra-deep Project" 850ks observation. We employed a
binning-free maximum likelihood method to segment the light-curves
into intervals of constants signal and identified flares on the basis
of both the amplitude and the time-derivative of the source
luminosity. We then derived and compared the flare frequency and
energy distribution of Cygnus OB2 and ONC sources. The effect of the
length of the observation on these results was investigated by
repeating the statistical analysis on five 100ks-long segments
extracted from the ONC data.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 84 147 X-ray properties of flaring sources in the
Cygnus OB2 region.
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See also:
J/AJ/107/1433 : Cygnus OB2 polarimetry (Kobulnicky+, 1994)
J/ApJS/149/123 : WSRT survey of Cygnus OB2 (Setia Gunawan+, 2003)
J/A+A/464/211 : Chandra and near-IR obs. of Cyg OB2 (Albacete Colombo+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [AFM2007] Source number according to Albacete Colombo
et al. (2007, Cat. J/A+A/464/211)
5- 20 A16 --- 2MASSJ Name of the 2MASS counterpart
(HHMMSSss+DDMMSSs)
22- 26 F5.2 solMass Mass ?=- Mass of star from Albacete Colombo et al.
(2007, Cat. J/A+A/464/211)
28- 30 I3 ct Phot Net detected photon from Albacete Colombo
et al. (2007, Cat. J/A+A/464/211)
32- 35 F4.2 keV Ex Median photon energy from Albacete Colombo
et al. (2007, Cat. J/A+A/464/211)
37- 41 F5.2 [10-7W] logLX X-ray luminosity from Albacete Colombo et al.
(2007, Cat. J/A+A/464/211)
43- 47 F5.2 [-] logPKS Logarithm of the KS-test significance (1)
49- 54 F6.3 ct/ks CR Count rate of the characteristic level
from MLB analysis
56- 60 F5.2 s Tflr Flare duration from MLB analysis
62- 66 F5.2 [10-7W] LXpeak Unabsorbed LX at the flare peak was computed
using CF, from MLB analysis
68- 72 F5.2 keV Eflr Flare energy from MLB analysis
74- 78 F5.2 h tau.m Measure of the flare's decay time, Efit/Lmax,
from MLB analysis
80- 84 F5.2 h tau.f ?=- Fitted decay time of flare
from MLB analysis
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Note (1): Logarithm of the KS-test significance with values ←4 truncated
at that value: sources with log(PKS)←3.0 can be considered almost
definitively variable as we expect at most one of the 1003 sources
(i.e. 0.1%) to be erroneously classified as variable.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 30-Nov-2007