J/A+A/668/A101 Flaring giants (Olah+, 2022)
Characteristics of flares on giant stars.
Olah K., Seli B., Kovari Zs., Kriskovics L., Vida K.
<Astron. Astrophys. 668, A101 (2022)>
=2022A&A...668A.101O 2022A&A...668A.101O (SIMBAD/NED BibCode)
ADC_Keywords: Stars, flare ; Stars, giant ; Photometry ; Optical
Keywords: stars: activity - stars: late-type - stars: flare
Abstract:
Although late-type dwarfs and giant stars are substantially different,
their flares are thought to originate in similar physical processes
and differ only by a scale factor in the energy levels. We study the
validity of this approach.
We search for characteristics of flares on active giants, which might
be statistically different from those on main-sequence stars.
We used nearly 4000 flares of 61 giants and 20 stars of other types
that were observed with Kepler in long-cadence mode, which is the only
suitable database for this comparative study. For every flare, we
derived the duration and energy and gathered stellar parameters.
Correlations between the flare characteristics and various stellar
parameters were investigated.
Strong correlations are found between the flare duration and the
surface gravity, luminosity, and radii of the stars. Scaled flare
shapes appear to be similar on giants and dwarfs with a 30 min
cadence. The logarithmic relation of flare energy and duration is
steeper for stars with lower surface gravity. Observed flares are
longer and more energetic on giants than on dwa rfs on average.
The generalized linear scaling for the logarithmic relation of flare
energy and duration with a universal theoretical slope of 1/3 should
slightly be modified by introducing a dependence on surface gravity.
Description:
We present the parameters of the 86 studied stars, and the catalog of
flares observed by the Kepler space telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 86 Stellar parameters
table2.dat 66 4368 Flare parameters
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC Kepler Input Catalog ID
10- 13 I4 K Teff ? Effective temperature
15- 18 F4.2 [cm/s2] logg ? Surface gravity
20- 24 F5.2 --- [Fe/H] ? Metallicity
26- 29 F4.2 Msun Mass ? Mass
31- 35 F5.2 Rsun Rad ? Radius
37- 42 F6.2 Lsun Lbol ? Bolometric luminosity
44- 48 A5 --- LumClass Luminosity class (dwarf or giant)
50- 55 F6.1 min taumedian Median flare duration
57- 59 I3 --- Nflares Number of Kepler flares
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC Kepler Input Catalog ID
10- 28 F19.14 d tpeak Peak time in BJD
30- 35 F6.1 min t12 Flare width time scale
37- 42 F6.1 min tau Duration
44- 48 F5.2 min ED Equivalent duration
50- 58 E9.3 10-7W EKepler ?=- Flare energy in the Kepler band
60- 66 A7 --- Type Simple or complex flare
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Acknowledgements:
Balint Seli, seli.balint(at)csfk.org
(End) Patricia Vannier [CDS] 17-Oct-2022