J/A+A/704/A274 Magnetic activity of M dwarfs from LAMOST DR10 (Li+, 2025)
Magnetic activity of M dwarf stars from the LAMOST DR10 medium-Resolution
survey.
Li W., Zhang L., Su T., Wang Y., Han X.L., Misra P.
<Astron. Astrophys. 704, A274 (2025)>
=2025A&A...704A.274L 2025A&A...704A.274L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Stars, flare ; Optical
Keywords: catalogs - surveys - stars: activity - stars: chromospheres
Abstract:
M dwarf stars (red dwarfs), the most common stars in the Milky Way (70
percent of all stars), have low temperatures and masses but exhibit
strong magnetic activity, such as flares, starspots, and coronal mass
ejection (CME). Studying their magnetic activity helps understand the
internal structure and evolutionary processes of stars, as well as
their impact on the environments of surrounding planets. This study
uses medium-resolution spectral (MRS) data of M dwarf stars from the
Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST)
Data Release 10 (DR) to conduct a comprehensive and in-depth
investigation of stellar magnetic activity, flare, and starspot
variations. By cross-matching the low-resolution spectral (LRS) M
dwarf star catalog from LAMOST DR10 MRS data, we have successfully
identified 20279 M dwarfs and obtained a total of 708969
medium-resolution spectral datasets. These data provide a rich
foundation for studying stellar magnetic fields and activity
characteristics. Additionally, we cross-matched the data with light
curves from the Transiting Exoplanet Survey Satellite (TESS),
acquiring light curve data for 2868 stars, among which 891 flare
stars were identified, providing important samples for the statistical
characteristics and physical mechanisms of flare events. By combining
with Gaia data, we clarified the spatial distribution characteristics
of M dwarfs in the Milky Way. In statistical studies of M dwarf stars
magnetic activity using LAMOST medium- resolution spectra, it has been
found that as the effective temperature of M dwarf stars increases,
their stellar activity diminishes, though this trend becomes less
evident for Teff>3600K, and the amplitude of Halpha line
variations becomes more dramatic for later spectral types. In a sample
of 11868 M dwarfs with a signal-to-noise ratio exceeding 10, we found
that 1676 exhibited Halpha emission features, i.e., were active
stars. Also, among the 891 flare stars identified from TESS light
curve data, 7496 flare events were detected. Among the 119 stars with
EW Halpha flare-like variations, 25 were flare stars in TESS light
curve data. Research has also clarified that the activity of M dwarf
stars in the Milky Way decreases with increasing vertical distance
from the galactic disk. Furthermore, by combining LAMOST spectral
surveys with TESS light curve data, a positive correlation between
chromospheric activity, as indicated by Halpha lines, and star spot
area has been established.Additionally, studies show a positive
correlation between flare energy and duration in M dwarf stars, with
the slope of this correlation decreasing for later spectral types.
Finally, through analyzing the asymmetry of Halpha lines, two
potential CME candidates have been identified.
Description:
File table1 present the stellar parameters of M dwarf stars from
LAMOST DR10, encompassing crucial details such as LAMOST name, Local
modified Julian day, signal to noise ratio, spectral types , stellar
effective temperature, stellar surface gravity, and Gaia G-band
magnitude, GBP-GRP magnitude, metallicity.
File table2 compiled the stellar parameters of M dwarf stars obtained
through calculation and cross-matching, it includes LAMOST name, EW
Halpha calculated from the dispersion spectrum, stellar activity
classification, stellar rotation period, Rossby number, chromospheric
activity index, stellar convective turnover time, stellar mass,
stellar radius, EW Halpha energy value of flare-like variable stars.
File table3 present the stellar flare parameters of M dwarf stars, it
includes LAMOST name, flare peak time of stellar flare events, flare
onset time of stellar flare events, flare decay time of stellar flare
events, stellar flare duration, stellar flare amplitude, flare energy,
stellar starspot area.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 110 709103 Stellar parameters of M dwarf stars from
LAMOST DR10
table2.dat 117 14661 The stellar parameters of M dwarf stars obtained
through calculation and cross-matching
table3.dat 98 8585 Stellar flare parameters of M dwarf stars
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See also:
J/ApJ/849/36 : Flaring activity of M dwarfs in the Kepler field (Yang+, 2017)
J/A+A/637/A22 : M dwarfs rotation-activity relations and flares (Raetz+, 2020)
J/ApJ/905/107 : Spectroscopic activity indicators of TIC stars (Medina+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- LAMOST LAMOST Name (JHHMMSS.ss+DDMMSS.s)
21- 29 F9.5 deg RAdeg Right Ascension (J2000)
31- 39 F9.5 deg DEdeg Declination (J2000)
41- 45 I5 --- medLMJD Local modified Julian day
in medium resolution
47 A1 --- medBand [BR] B and R band spectra
in medium resolution
49- 54 F6.2 --- medSNR Signal to noise ratio in medium resolution
56- 57 A2 --- lowSubclass Spectral types in low resolution
59- 66 F8.2 K Teff ? Effective temperature in low resolution
69- 74 F6.2 K e_Teff ? Effective temperature error
76- 80 F5.2 [cm/s2] logg ? Surface gravity in low resolution
82- 88 F7.4 [cm/s2] e_logg ? Surface gravity error
90- 96 F7.3 mag Gmag ? Gaia G-band magnitude
98-103 F6.3 mag Bp-Rp ? GBP-GRP colour
105-110 F6.3 --- [Fe/H] ? Metallicity, [Fe/H]
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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- 19 A19 --- LAMOST LAMOST name (JHHMMSS.ss+DDMMSS.s)
21- 26 E6.1 0.1nm EWHa Hα equivalent width calculated from
the dispersion spectrum
28- 36 F9.4 0.1nm e_EWHa EWHa error
38- 40 A3 --- MA [Yes No] Stellar activity classification
42- 48 F7.3 d Per ? Stellar rotation period
50- 56 F7.4 --- Ro ? Rossby number
58- 67 E10.3 --- RHa ? Chromospheric activity index
69- 77 F9.4 d tao ? Stellar convective turnover time
79- 84 F6.3 Msun Mass ? Stellar mass
86- 93 F8.4 kpc R ? Distance R from the point where the star's
spatial position is projected onto the
Galactic plane to the Galactic center
95-101 F7.4 kpc Z ? Distance perpendicular to the Galactic plane
103-108 F6.3 Rsun Rad ? Stellar radius
110-117 E8.3 --- EWHabol ? EWHa energy value of flare-like
variable stars
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- LAMOST LAMOST name (JHHMMSS.ss+DDMMSS.s)
21- 32 F12.6 d PeakTime ? Flare peak time of stellar flare events
(BJD-2450000)
34- 45 F12.6 d BeginTime ? Flare onset time of stellar flare events
(BJD-2450000)
47- 58 F12.6 d EndTime ? Flare decay time of stellar flare events
(BJD-2450000)
60- 69 F10.5 min Duration ? Stellar flare duration
71- 82 F12.9 mag Amplitude ? Stellar flare amplitude
84- 91 E8.3 10-7J Ebol ? Flare energy of M dwarf stars
93- 98 F6.3 --- Reff ? Stellar starspot area
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Acknowledgements:
Liyun Zhang, 3110953686(at)qq.com
(End) Patricia Vannier [CDS] 02-Oct-2025