J/MNRAS/505/L79 Characteristic time of stellar flares (Yan+, 2021)
Characteristic time of stellar flares on Sun-like stars.
Yan Y., He H., Li C., Esamdin A., Tan B. L., Zhang L. Y., Wang H.
<Mon. Not. R. Astron. Soc. 505, L79 (2021)>
=2021MNRAS.505L..79Y 2021MNRAS.505L..79Y (SIMBAD/NED BibCode)
ADC_Keywords: Stars, flare ; Stars, G-type
Keywords: stars: activity - stars: flare - stars: solar-type
Abstract:
Using the short-cadence data (1-min interval) of the Kepler space
telescope, we conducted a statistical analysis for the characteristic
time of stellar flares on Sun-like stars (SLS). Akin to solar flares,
stellar flares show rise and decay light-curve profiles, which reflect
the two distinct phases (rise phase and decay phase) of the flare
process. We derived characteristic times of the two phases for the
stellar flares of SLS, resulting in a median rise time of about 5.9min
and a median decay time of 22.6min. It is found that both the rise
time and the decay time of the stellar flares follow a lognormal
distribution. The peak positions of the lognormal distributions for
flare rise time and decay time are 3.5min and 14.8min, respectively.
These time values for stellar flares are similar to the time-scale of
solar flares, which supports the idea that stellar flares and solar
flares have the same physical mechanism. The statistical results
obtained in this work for SLS can be a benchmark of flare
characteristic times when comparing with other types of stars.
Description:
The SLS samples were identified from the objects observed in Kepler's
short-cadence mode by the following criteria: (1) the effective
temperature is in the range of 5600-6000K; (2) the surface gravity
is in the range of 3.9-4.9 (in cgs); (3) they should be ordinary
single stars.
The start, peak, and end times of each flare are defined as follows:
(1) the start time is the time of the data point where the flare flux
suddenly rises from the background level; (2) the peak time is the
time of the data point at which the flare intensity reaches its peak;
(3) the end time is the time of the data point where the flare flux is
asymptotically tangent to the background level. The flare rise time
and decay time are the difference between the peak time and the start
time and the difference between the end time and the peak time,
respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 29 20 Table of star samples
flares.dat 57 184 Table of flare samples
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC Kepler ID
10- 15 F6.3 mag kepmag [7.397/11.662] Kepler magnitude
17- 20 I4 K Teff [5607/5987] Effective temperature
22- 26 F5.3 [cm/s2] logg [4.053/4.802] Surface gravity
28- 29 I2 --- NumFlare [1/39] Number of flares
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Byte-by-byte Description of file: flares.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- No [1/184] Serial Number of flares
5- 12 I8 --- KIC Kepler ID
14- 23 F10.5 d tstart Start time of flare
25- 34 F10.5 d tpeak Peak time of flare
36- 45 F10.5 d tend End time of flare
47- 51 F5.1 min Trise [1.0/152.0] Rise time of flare
53- 57 F5.1 min Tdecay [4.9/216.8] Decay time of flare
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Acknowledgements:
Han He, hehan(at)nao.cas.cn
(End) Yan Yan and Han He [NAOC, China], Patricia Vannier [CDS] 23-Jun-2021