J/A+A/698/A180 Short-term stellar activity in dM stars (Galletta+, 2025)
Exploring short-term stellar activity in M dwarfs: A volume-limited perspective.
Galletta G., Colombo S., Prisinzano L., Micela G.
<Astron. Astrophys. 698, A180 (2025)>
=2025A&A...698A.180G 2025A&A...698A.180G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Stars, M-type ; Photometry ; Optical
Keywords: catalogs - stars: activity - stars: flare
Abstract:
Flares are a form of stellar activity that occur over short timescales
but produce highly energetic outbursts. Studying stellar flares is
crucial because they can significantly alter the circumstellar
environment by producing intense high-energy radiation. Understanding
stellar flares is essential for clarifying the environment in which
planets evolve, as flares can influence planetary atmospheres by
driving photoevaporation and photochemical processes. M dwarfs are of
significant interest due to their high flare activity rates and the
potential presence of exoplanets within their habitable zones, whose
atmospheres may be influenced by flare-emitted radiation.
We aimed to define the flaring properties of an unbiased sample of M
dwarfs with limited volume. Using data from the Transiting Exoplanet
Survey Satellite (TESS), we characterized the frequency, energy
distribution, and temporal properties of flares in nearby stars.
We selected a volume-limited sample of M dwarfs within 10pc from
Earth from the Gaia DR3 catalog. We analyzed TESS light curves using
an iterative Gaussian process fitting technique to remove long-term
stellar activity signals, enabling the identification and
characterization of impulsive flare events. For each flare, we derived
the amplitudes, timescales, and total energy emitted.
We analyzed 173 stars and detected 17229 flares, with 0 to 76
flares per TESS sector. We examined the frequency and energy
distribution of stellar flares using three representative stars to
illustrate the diversity in flare activity. We observed flares with a
minimum energy of ∼1029erg and typical durations ranging from 2
to 8000 seconds. We modeled the cumulative flare energy distribution
using one-slope and two-slope fits, yielding average slopes of
-0.79±0.64 and -1.23±1.32, respectively. We defined
the Flare Energy Index (GF.01) to characterize the flare frequency and
revealed two distinct populations. Fainter stars exhibited fewer
high-energy flares, whereas brighter stars exhibited more frequent
low-energy flares. We analyzed two highly active stars with the
largest number of TESS sectors, G 227-22 and G 258-33, were analyzed
over a long time baseline to explore their flare properties and energy
distributions.
Description:
The objective of this work is to define the flaring properties of an
unbiased, volume-limited sample of M-type stars. Using the Transiting
Exoplanet Survey Satellite (TESS), we aim to characterize the
frequency, energy distribution, and temporal properties of flares in
nearby stars. We selected a volume-limited sample of M-type stars
within 10 parsecs from the Gaia DR3 catalog. TESS light curves were
analyzed using an iterative Gaussian process fitting technique to
remove long-term stellar activity signals, allowing us to identify and
characterize impulsive flare events. For each flare, we derived
amplitudes, timescales, and the total energy emitted.We analyzed 173
stars and detected 17229 flares, with 0 to 76 flares per TESS sector.
Table shows the name of the stars analyzed, the TESS sectors, the
number of flares, the Lbol, the slopes and the energy breaks. The
value --- indicates the one-segment fit cases that is without energy
break.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 46 172 List of targets
table3.dat 71 751 Table of TESS sector activity
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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: stars.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- Name Name of the target star
24- 25 I2 h RAh Simbad right ascension (J2000)
27- 28 I2 min RAm Simbad right ascension (J2000)
30- 34 F5.2 s RAs Simbad right ascension (J2000)
36 A1 --- DE- Simbad declination sign (J2000)
37- 38 I2 deg DEd Simbad declination (J2000)
40- 41 I2 arcmin DEm Simbad declination (J2000)
43- 46 F4.1 arcsec DEs Simbad declination (J2000)
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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- 22 A22 --- Name Name of the target star
24- 26 A3 --- Sector TESS sector (e.g., "s39", "s2", etc.)
28- 30 I3 --- Flare Number of flares detected
32- 40 F9.7 Lsun Lbol Bolometric luminosity
42- 50 F9.7 Lsun e_Lbol Bolometric luminosity error
52- 57 F6.2 --- Slope Slope of the flare distribution
59- 62 F4.2 --- e_Slope Slope of the flare distribution error
64- 71 E8.3 10-7W EBreak ?=- Break energy in erg
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Acknowledgements:
Gabriele Galletta, gabriele.galletta(at)inaf.it
References:
Ricker et al., 2016, in Space Telescopes and Instrumentation 2016:
Optical, Infrared, and Millimeter Wave, Vol. 9904, SPIE, 767-78
Prusti et al., 2016A&A...595A...1G 2016A&A...595A...1G, Cat. I/337
(End) Patricia Vannier [CDS] 18-Apr-2025