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
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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 84 147 X-ray properties of flaring sources in the Cygnus OB2 region.
See also: J/AJ/107/1433 : Cygnus OB2 polarimetry (Kobulnicky+, 1994) J/A+A/464/211 : Chandra and near-IR obs. of Cyg OB2 (Albacete Colombo+, 2007) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
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
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.
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 30-Nov-2007
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