J/ApJ/961/130 Chandra X-ray flares from CSC 2.0 and Gaia DR3 (Zhao+, 2024)
A statistical study of soft X-ray flares on solar-type stars.
Zhao Z.H., Hua Z.Q., Cheng X., Li Z.Y., Ding M.D.
<Astrophys. J., 961, 130 (2024)>
=2024ApJ...961..130Z 2024ApJ...961..130Z
ADC_Keywords: Stars, flare; X-ray sources; Photometry; Optical; Colors;
Stars, distances
Keywords: X-ray stars ; Stellar activity ; Stellar flares ;
Stellar x-ray flares ; Flare stars ; Magnetic fields ;
Stellar magnetic fields ; Stellar atmospheres ; Stellar astronomy ;
Stellar physics
Abstract:
The statistical characteristics of stellar flares at optical bands
have received extensive study, but they remain to be studied at soft
X-ray bands, in particular for solar-type stars. Here, we present a
statistical study of soft X-ray flares on solar-type stars, which can
help in understanding the multiwavelength behaviors of stellar flares.
We mainly use Chandra Source Catalog Release 2.0, which includes a
number of flaring stars with denoted variability, and Gaia Data
Release 3, which includes the necessary information for classifying
stars. We also develop a set of methods for identifying and
classifying stellar soft X-ray flares and estimating their properties.
A detailed statistical investigation of 129 flare samples on
103 nearby solar-type stars as selected yields the following main
results. (1) The flare energy emitted at the soft X-ray band in our
sample ranges from ∼1033 to ∼1037erg, and the majority of them are
superflares, with the most energetic one having energy of
6.0-4.7+3.2x1037erg. (2) The flare duration is related to its
energy as formulated by
Tduration,SXR∝Eflare,SXR0.201±0.024, which is different
from those derived at optical and near-IR bands, indicating distinct
radiation mechanisms at different bands. (3) The frequency
distribution of stellar flares as a function of energy is formulated
as dNflare/dEflare,SXR∝Eflare,SXR-1.77, which is
similar to the results found at other bands and on other types of
stars, indicating that the energy emitted at the soft X-ray band could
be a constant fraction of the full-band bolometric energy.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table34.dat 328 129 Physical and observational properties of host stars
and properties of stellar flares (Tables 3 and 4)
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See also:
IX/57 : The Chandra Source Catalog (CSC), Release 2.0 (Evans+, 2019)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/ApJ/675/1254 : M37 variable stars (Hartman+, 2008)
J/other/Nat/485.478 : Superflares on solar-type stars (Maehara+, 2012)
J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013)
J/A+A/581/A28 : Stellar X-ray flares from the 2XMM catalog (Pye+, 2015)
J/ApJ/851/91 : Stat. studies of solar white-light flares (Namekata+, 2017)
J/ApJ/849/36 : Flaring activity of M dwarfs in Kepler field (Yang+, 2017)
J/A+A/620/A55 : Magnetic flaring from PMS stars spectra (Flaccomio+, 2018)
J/MNRAS/494/3596 : Superflares in solar-type stars with TESS (Doyle+, 2020)
J/ApJ/890/46 : Superflares on solar-type stars from TESS 1st yr (Tu+, 2020)
J/ApJ/916/32 : X-ray superflares from PMS stars (Getman+, 2021)
J/MNRAS/517/2925 : ORB6 binaries in Gaia EDR3 (Chulkov+, 2022)
Byte-by-byte Description of file: table34.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [0/128] Running sequence number
5- 9 I5 --- ObsID [606/16444] Chandra observation identifier
11- 19 F9.5 deg RAdeg [6.2/346] CSC 2.0 Right Ascension (J2000)
21- 29 F9.5 deg DEdeg [-74.3/65] CSC 2.0 Declination (J2000)
31- 40 E10.4 kpc Dist [0.066/2.43] Gaia DR3 distance
42- 51 E10.4 kpc e_Dist [4.9e-05/0.45] Uncertainty in Dist
53- 56 I4 K Teff [5110/5990] Gaia DR3 effective temperature
58- 62 F5.3 [cm/s2] logg [4/4.8] Gaia DR3 log surface gravity
64- 69 I6 s Time [10044/175692] Total elapsed time of
observation from CSC 2.0 (gti_elapse)
71- 75 F5.3 mag Bp-Rp [0.76/3.16] Gaia DR3 Blue-Red passband color
77- 82 F6.3 mag Gmag [9.3/17.31] Gaia DR3 mean G band magnitude
84- 88 F5.3 --- RUWE [0.73/5.86] Gaia DR3 renormalized unit
weight error
90- 94 I5 s TRise [0/42756] Chandra soft X-ray band flare rise
time
96- 100 I5 s TDecay [0/30118] Chandra soft X-ray band flare
decay time
102- 106 F5.2 --- Ratio [0/70.76] The TDecay/TRise ratio
108- 112 I5 s TDur [89/71315] Chandra soft X-ray band flare
duration
114- 120 F7.5 ct/s CRquies [0.00015/0.2] Chandra soft X-ray band
quiescent count rate
122- 128 F7.5 ct/s CRpeak [0.003/1.3] Chandra soft X-ray band flare
peak count rate
130- 137 E8.2 mW/m2 FPeak [3e-14/1.62e-10]?=0 Chandra soft X-ray band
flare peak flux; erg/s/cm2
139- 146 E8.2 mW/m2 e_FPeak [1e-14/5.3e-11]?=0 Lower uncertainty in FPeak
148- 155 E8.2 mW/m2 E_FPeak [4.6e-14/1.1e-10]?=0 Upper uncertainty in
FPeak
157- 164 E8.2 10-7W LPeak [1e+29/1e+34]?=0 Chandra soft X-ray band
flare peak luminosity; erg/s
166- 173 E8.2 10-7W e_LPeak [5e+28/1e+34]?=0 Lower uncertainty in LPeak
175- 182 E8.2 10-7W E_LPeak [2.3e+29/1.8e+34]?=0 Upper uncertainty in
LPeak
184- 191 E8.2 10-7J EFlare [9e+32/6e+37]?=0 Chandra soft X-ray band
flare energy; erg
193- 200 E8.2 10-7J e_EFlare [4e+32/4.7e+37]?=0 Lower uncertainty in
EFlare
202- 209 E8.2 10-7J E_EFlare [1.9e+33/7e+37]?=0 Upper uncertainty in
EFlare
211- 219 E9.2 --- aRise [-2.1/6.2]?=0 Chandra soft X-ray band flare
rise spectral index
221- 228 E8.2 --- e_aRise [0.1/5.3]?=0 Lower uncertainty in aRise
230- 237 E8.1 --- E_aRise [-6.2/5.8]?=0 Upper uncertainty in aRise
239- 247 E9.2 --- aDecay [-0.45/10]?=0 Chandra soft X-ray band flare
decay spectral index
249- 256 E8.2 --- e_aDecay [0.16/9.4]?=0 Lower uncertainty in aDecay
258- 266 E9.2 --- E_aDecay [-10/8]?=0 Upper uncertainty in aDecay
268- 276 E9.2 --- aFlare [-0.34/10]?=0 Chandra soft X-ray band flare
spectral index
278- 285 E8.2 --- e_aFlare [0.1/6.7]?=0 Lower uncertainty in aFlare
287- 295 E9.2 --- E_aFlare [-10/6]?=0 Upper uncertainty in aFlare
297- 305 E9.2 --- aRatio [-0.8/3.6]?=0 The alphaDecay/alphaRise ratio
307- 314 E8.2 --- e_aRatio [0.04/1100]?=0 Lower uncertainty in aRatio
316- 324 E9.2 --- E_aRatio [-5400/19]?=0 Upper uncertainty in aRatio
326- 328 A3 --- LC Light curve categories (1)
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Note (1): Light curve category as follows:
F = Flare (27 occurrences)
S = Flare with single Bayesian Block (84 occurrences)
M-F = Flare with multiple flaring phases (extracted into F; 3 occurrences)
M-S = Flare with multiple flaring phases (extracted into S; 15 occurrences)
See Section 2.3 for full details.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Apr-2026