J/A+A/699/A322 Magnetic activity of RS CVn stars (Xu+, 2025)
Magnetic activity of RS CVn stars based on TESS and LAMOST surveys.
Xu L., Zhang L., Wang Y., Su T., Han X.L., Misra P., Shu A., Pi Q.
<Astron. Astrophys. 699, A322 (2025)>
=2025A&A...699A.322X 2025A&A...699A.322X (SIMBAD/NED BibCode)
ADC_Keywords: Stars, flare ; Spectra, optical ; Abundances
Keywords: stars: activity - stars: flare - stars: statistics
Abstract:
Understanding flare activity in RS CVn stars is crucial for
elucidating their magnetic activity properties. This study aims to
conduct a detailed statistical analysis of stellar flare
characteristics in RS CVn-type stars using data from the Transiting
Exoplanet Survey Satellite (TESS) and the Large Sky Area Multi- Object
Fiber Spectroscopic Telescope (LAMOST) surveys.
We initially identified 80305 candidates from the International
Variable Star Index (VSX) and refined the sample to 1812 RS CVn stars
through SIMBAD cross-matching. Using TESS 2-minute cadence data, we
processed 958 light curves from 246 targets, detecting 1254 flare
events among 144 flare stars. By cross-matching with the LAMOST DR10
data, we obtained 148 and 482 low resolution and medium resolution
spectra for 90 and 37 RS CVn-type sources. With LAMOST data, we
calculated and statistically analyzed several stellar magnetic
activity indicators, like Hα equivalent width. Combining Gaia survey,
TESS Input Catalog, and LAMOST survey data, we investigated
relationships between flare parameters and stellar characteristics.
Of the 1254 observed flare events, over 89% had durations <1 hour, and
more than 90% had amplitudes <0.01. The flare stars concentrate within
temperature (4000-6500K), mass (<1M☉), and radius (0-5R☉)
ranges, with 21 stars deriving parameters from their primary
components. The flare occurrence percentage is higher for temperatures
between 3000-4000K and orbital periods <10 days. The duration ( τ
) is related to the energy (E) by the power law
τ∝E0.3-0.41. The power-law index α of the
cumulative flare frequency distribution is about 1.22±0.09. We
analyzed flare rotational phases and found no preference, indicating
random occurrence. Medium-resolution spectra revealed asymmetry in the
Hα profiles of one source TIC 46296256, which might be caused by
the coronal rain, binary motion, or chromospheric condensation.
Description:
Table A1 lists the parameters of the 1254 flare events, Table A2
presents a comprehensive list of stellar parameters for the RS CVn
stars, including essential details such as effective temperature,
mass, and radius. The parameters related to chromospheric activity,
such as LAMOST Name, OBJECT, OBSID,and Teff are listed in Tables A4 and
A5 for both low resolution and medium resolution spectra.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 82 1254 Parameters of flare events from TESS
tablea2.dat 147 246 Stellar parameters of TESS objects
tablea4.dat 108 99 Parameters of Low Resolution
tablea5.dat 155 482 Parameters of Medium Resolution
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See also:
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- TIC TESS ID, TIC NNNNNNNNN
11- 12 I2 --- Sector [1/74] TESS SECTOR
14- 20 F7.5 --- Amp Flare amplitude
22- 28 E7.5 --- e_Amp Flare amplitude error
30- 37 F8.3 d BeginTime Flare begin time
39- 46 F8.3 d PeakTime Flare peak time
48- 55 F8.3 d EndTime Flare end time
57- 64 F8.6 d Dur Flare Duration
66- 73 E8.3 10-7W Ebol ?=- Bolometric flare energy
75- 82 E8.3 10-7W e_Ebol ?=- Bolometric flare energy error
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [TIC]
5- 13 I9 --- TIC TESS ID, NNNNNNNNN
15- 22 F8.4 deg RAdeg Right ascension (J2000)
24- 31 F8.4 deg DEdeg Declination (J2000)
33- 39 F7.4 mag TESSmag ?=- TESS magnitude
41- 45 F5.3 mag e_TESSmag ?=- TESS magnitude error
47- 52 F6.4 [cm/s2] logg ?=- Log surface gravity
54- 59 E6.4 [cm/s2] e_logg ?=- Log surface gravity error
61- 65 I5 K Teff ?=- Effective temperature
67- 72 F6.1 K e_Teff ?=- Effective temperature error
74- 78 F5.2 Rsun Rad ?=- Radius
80- 84 F5.3 Rsun e_Rad ?=- Radius error
86- 89 F4.2 Msun Mass ?=- Mass
91- 95 F5.3 Msun e_Mass ?=- Mass error
97-103 F7.4 [-] [Fe/H] ?=- Metallicity [Fe/H]
105-109 F5.3 [-] e_[Fe/H] ?=- Metallicity [Fe/H] error
111-116 F6.3 Gyr Age ?=- Age
118-125 F8.4 d Per ?=- Period
127-135 F9.4 pc Dist ?=- Distance
137-144 F8.4 pc e_Dist ?=- Distance error
146-147 I2 --- FlareNum ?=- The counts of flare events
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- LAMOST LAMOST identifier (JHHMMSS.ss+DDMMSS.s)
21- 32 F12.9 0.1nm EWHa Hα equivalent width
34- 44 F11.9 0.1nm e_EWHa Hα equivalent width error
46- 56 F11.7 deg RAdeg Right ascension (J2000)
58- 67 F10.7 deg DEdeg Declination (J2000)
69- 77 I9 --- ObsID LAMOST unique number ID of this spectrum
79- 83 I5 d MJD Modified Julian Date
85- 89 F5.3 [cm/s2] logg ?=- Log surface gravity
91- 94 F4.2 [cm/s2] e_logg ?=- Log surface gravity error
96- 99 I4 K Teff ?=- Effective temperature
101-106 F6.2 K e_Teff ?=- Effective temperature error
108 A1 --- VarEW [Y/N] Variation in EW_Halpha
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Byte-by-byte Description of file: tablea5.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- --- [LAMOST]
8- 26 A19 --- LAMOST LAMOST identifier, JHHMMSS.ss+DDMMSS.s
28- 46 F19.16 0.1nm EWHa Original Hα equivalent width
48- 65 F18.16 0.1nm e_EWHa Original Hα equivalent width error
67- 75 I9 --- ObsID LAMOST unique number ID of this spectrum
77- 86 F10.6 deg RAdeg Right ascension (J2000)
88- 96 F9.6 deg DEdeg Declination (J2000)
98-107 A10 --- ExtName The extension name
109-116 I8 d LMJM ? Local Modified Julian Day
118-123 F6.2 --- SNR Spectrum signal-to-noise ratio
125-128 I4 K Teff Effective temperature
130-135 F6.4 [cm/s2] logg ?=- Log surface gravity
137-143 F7.4 [-] [Fe/H] ?=- Metallicity [Fe/H]
145-153 F9.4 pc Dist ?=- Distance
155 A1 --- VarEW [Y/N] Variation in EW_Halpha
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Acknowledgements:
Liyun Zhang, liy_zhang(at)hotmail.com
Xu Lulu, 2456952726(at)qq.com
(End) Xu Lulu [GZU, P.R. China], Patricia Vannier [CDS] 15-May-2025