J/ApJS/282/29 Magnetic activity of M-type stars from LAMOST+TESS (Ren+, 2026)
Magnetic activity in M-type stars based on LAMOST DR11 and TESS observations.
Ren L., Zhang L.-Y., Han X.L., Su T., Li W., Wang Y., Misra P.
<Astrophys. J. Suppl. Ser., 282, 29 (2026)>
=2026ApJS..282...29R 2026ApJS..282...29R
ADC_Keywords: Stars, M-type; Spectra, optical; Effective temperatures;
Equivalent widths; Stars, flare; Spectral types; Photometry
Keywords: Stellar chromospheres ; M stars ; Stellar activity
Abstract:
We have used 898,351 M-type stellar spectra released by Large Sky Area
Multi-Object Fiber Spectroscopic Telescope DR11 to calculate the
equivalent width of the CaII infrared triplet (IRT) lines, the
residual chromospheric emission, and the parameter R'8542, which is
defined as the ratio of the luminosity of the 8542Å line to the
stellar bolometric luminosity. The chromospheric activity of M dwarfs
reaches its maximum around an effective temperature of 3700K,
corresponding to a spectral type of approximately M6. The stellar
photospheric activity begins to become significant at around 3800K,
and the trend gradually becomes weaker when approaching 3200K, which
may be due to the influence of the magnetic activity saturation zone.
Furthermore, metallicity also influences the intensity of the
chromospheric activity. We found that chromospheric and photospheric
activity in M dwarfs are correlated, and that both types of activity
are influenced by stellar rotation. Additionally, we crossmatched our
catalog with the Transiting Exoplanet Survey Satellite and identified
23,079 flare events from 3280 stars. Our results show that the
majority of the M dwarf flare radiation energy is below 1036erg, and
the flare duration and energy of nearly all spectral types follow a
power-law distribution, i.e., dN/dE∝E-a with α=2. For
the cumulative flare frequency distribution's power-law index, we
found the range to be between 1.44 and 2. We found that the power-law
index α for fully convective M-type stars is approximately
1.61±0.08, while for non-fully convective M-type stars, it is around
1.78±0.11.
Description:
Based on the LAMOST DR11 data (released on 2024 March 31), LAMOST has
released 11,939,296 low-resolution (R∼1800) spectra.
The three spectral lines of CaII infrared triplet (IRT) have
wavelengths 8498, 8542, and 8662Å, which fall within the wavelength
range observed by LAMOST's low-resolution spectra (with a range of
3700-9100Å). In the present study, we have only used the
low-resolution spectral data.
To date, the TESS mission has observed nearby stars at intervals of
30 and 2 minutes. See Section 2.2.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 144 1035668 LAMOST DR11 low-resolution M-type star catalog
table2.dat 133 23079 Flare parameters of exoplanet system of TESS
table4.dat 73 245939 Remaining chromospheric emission data table
table5.dat 112 4444 LAMOST and TESS common observation source
calculation table
--------------------------------------------------------------------------------
See also:
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
V/162 : LAMOST DR11 catalogs (Luo+, 2026)
J/A+A/327/1039 : Structure and evolution of low-mass stars (Chabrier+ 1997)
J/A+AS/124/359 : Ca II triplet lines in cool stars (Mallik 1997)
J/MNRAS/298/332 : Chromospheric activity-age relation (Rocha-Pinto+ 1998)
J/AJ/128/426 : Subdwarfs in the SDSS (West+, 2004)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/AJ/140/1402 : M dwarf flares from SDSS spectra (Hilton+, 2010)
J/AJ/141/50 : White-light flares on cool stars (Walkowicz+, 2011)
J/AJ/143/67 : SLoWPoKES. II. Wide, low-mass binaries (Dhital+, 2012)
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (Sullivan+, 2015)
J/A+A/594/A39 : LAMOST-Kepler param. and activity indicators (Frasca+, 2016)
J/ApJ/834/85 : Hα emission in nearby M dwarfs (Newton+, 2017)
J/ApJ/849/36 : Flaring activity of M dwarfs in Kepler field (Yang+, 2017)
J/MNRAS/476/908 : Chromospheric activity in 4 open clusters (Fang+, 2018)
J/ApJ/858/55 : K2 ultracool dwarfs survey. III. M6-L0 flares (Paudel+, 2018)
J/ApJS/247/9 : FGK stars magnetic activity in LAMOST-Kepler (Zhang+, 2020)
J/ApJ/906/72 : 2344 superflares on 266 solar-type stars (Okamoto+, 2021)
J/ApJS/253/19 : Halpha and other EWs of LAMOST M-type stars (Zhang+, 2021)
J/ApJ/926/204 : TESS campaign of low-mass flare stars (Howard+, 2022)
J/A+A/658/A57 : F-G-K stars activity indicators (Meunier+, 2022)
J/A+A/672/A37 : Activity indicators in M dwarfs (Ibanez Bustos+, 2023)
J/A+A/669/A15 : TESS flare events and physical parameters (Yang+, 2023)
J/ApJS/264/17 : Spectroscopic data of TESS objects with LAMOST (Zhang+, 2023)
J/ApJS/274/36 : Magnetic activity from LAMOST DR9, Gaia & TESS (Li+, 2024)
J/AJ/168/234 : Flares & flaring stars from TESS (Lin+, 2024)
J/A+A/684/A9 : Rotation periods for 261 M dwarfs (Shan+, 2024)
J/ApJS/271/60 : Magnetic activity of G stars from LAMOST+TESS (Su+, 2024)
J/A+A/686/A164 : Magnetic activity of radio stars (Wang+, 2024)
J/A+A/699/A322 : Magnetic activity of RS CVn stars (Xu+, 2025)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.7 deg RAdeg Right Ascension (J2000)
13- 22 F10.7 deg DEdeg [-9.7/89] Declination (J2000)
24- 31 F8.2 --- SNR [0/999]?=-9999 Signal to Noise in the z band
33- 42 A10 --- SpT Stellar spectral type or object type
44- 51 F8.2 [cm/s2] logg [-0.5/9.8]?=-9999 Stellar log surface gravity
53- 60 F8.2 [cm/s2] e_logg [0/24.6]?=-9999 Uncertainty in logg
62- 66 I5 K Teff [2300/60011]?=-9999 Effective temperature
68- 72 I5 K e_Teff [0/2367]?=-9999 Uncertainty in Teff
74- 85 F12.3 0.1nm EW8498 [-105070.3/25173585]?=-9999 Calculated
residual chromospheric from CaII 8498
Angstrom line; Angstroms
87- 95 F9.3 0.1nm e_EW8498 [0.01/17701]?=-9999 Uncertainty in EW8498
97- 108 F12.3 0.1nm EW8542 [-1991058/2074122]?=-9999 Calculated
residual chromospheric from CaII 8542
Angstrom line; Angstroms
110- 120 F11.3 0.1nm e_EW8542 [0.04/2077273]?=-9999 Uncertainty in EW8542
122- 134 F13.3 0.1nm EW8662 [-46215/661894668]?=-9999 Calculated
residual chromospheric from CaII 8662
Angstrom line; Angstroms
136- 144 F9.3 0.1nm e_EW8662 [0.006/2618]?=-9999 Uncertainty in EW8662
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 I10 --- TIC [893123/2053586891] TESS Input Catalog identifier
12- 22 F11.8 --- Amp [0.0026/34.82] Flare amplitude
24- 33 F10.8 --- e_Amp [0/0.55] Uncertainty in Amp
35- 45 F11.6 d Start [1386.27/3339.28] Beginning of the rise time in
light curve; BJD-2457000
47- 57 F11.6 d Peak [1386.27/3339.28] Time when light curve begins
to decline; BJD-2457000
59- 69 F11.6 d End [1386.28/3339.28] Flare end time; BJD-2457000
71- 80 F10.8 d Dur [0.005/5.3] Flare duration
82- 91 A10 --- SpT Stellar spectral type
or object type ("DoubleStar", "WD")
93- 96 I4 K Teff [0/8147] Stellar effective temperature
98- 102 I5 K e_Teff [0/265]?=-9999 Uncertainty in Teff
104- 109 F6.3 mag Tmag [9/16.3] TESS mean magnitude
111- 115 F5.3 mag e_Tmag [0/0.6] Uncertainty in Tmag
117- 124 E8.2 10-7J Eng [0/3.17e+38] Flare energy; erg
126- 133 E8.2 10-7J e_Eng [0/5.32e+35] Uncertainty in Eng
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.7 deg RAdeg Right Ascension (J2000)
13- 22 F10.7 deg DEdeg [-9.4/89] Declination (J2000)
24- 27 A4 --- SpT Stellar spectral type
29- 35 F7.4 0.1nm EW8498 [-1.2/6.1] Calculated residual chromospheric
from CaII 8498 Angstrom line
37- 43 F7.4 0.1nm EW8542 [-1.4/6.7] Calculated residual chromospheric
from CaII 8542 Angstrom line
45- 51 F7.4 0.1nm EW8662 [-0.8/2.9] Calculated residual chromospheric
from CaII 8662 Angstrom line
53- 59 F7.4 0.1nm e_EW8498 [0.008/12] Uncertainty in EW8498
61- 66 F6.4 0.1nm e_EW8542 [0/0.2] Uncertainty in EW8542
68- 73 F6.4 0.1nm e_EW8662 [0/0.2] Uncertainty in EW8662
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 I10 --- ObsID [504135/1127611220] LAMOST ObsID
12- 17 F6.2 --- SNR [40/666] Signal to noise in z band
19- 21 A3 --- SpT Stellar spectral type
23- 26 I4 K Teff [3102/4122] Effective temperature
28- 30 I3 K e_Teff [24/194] Uncertainty in Teff
32- 43 F12.9 d Prot [0.0027/28.8] Stellar rotation period
45- 49 F5.3 [cm/s2] logg [4/5.2] Stellar log surface gravity
51- 55 F5.3 [cm/s2] e_logg [0.03/0.51] Uncertainty in logg
57- 65 E9.2 --- R8542 [-9.01e-06/0.00012] Ratio of spectral line
luminosity to stellar radiance, R'8542
67- 74 E8.2 10-7J EBol [1.48e+32/4.74e+36]? Flare bolometric energy
76- 83 E8.2 --- Reff [0.0002/1.7] Effective range of light curve
fluctuation amplitude
85- 92 E8.2 --- e_Reff [5.8e-09/0.08] Uncertainty in Reff
94- 102 F9.3 --- zeta [-0.11/6.6]?=-9999 The ζ index
(section 3.4)
104- 112 F9.3 --- e_zeta [0/0.3]?=-9999 Uncertainty in zeta
--------------------------------------------------------------------------------
History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Jul-2026