J/A+A/694/A161 Stellar flare morphology with TESS (Seli+, 2025)
Stellar flare morphology with TESS across the main sequence.
Seli B., Vida K., Olah K., Gorgei A., Soos S., Pal A., Kriskovics L.,
Kovari Z.
<Astron. Astrophys. 694, A161 (2025)>
=2025A&A...694A.161S 2025A&A...694A.161S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, flare ; Optical
Keywords: Sun: flares - stars: activity - stars: flare - stars: statistics
Abstract:
Stellar flares are abundant in space photometric light curves. As they
are now available in large enough numbers, the statistical study of
their overall temporal morphology is timely.
We use light curves from the Transiting Exoplanet Survey Satellite
(TESS) to study the shapes of stellar flares beyond a simple
parameterization by duration and amplitude, and we reveal possible
connections to astrophysical parameters.
We retrained and used the flatwrm2 long-short term memory neural
network to find stellar flares in 2-min cadence TESS light curves from
the first five years of the mission (sectors 1-69). We scaled these
flares to a comparable standard shape and used principal component
analysis to describe their temporal morphology in a concise way. We
investigated how the flare shapes change along the main sequence and
tested whether individual flares hold any information about their host
stars. We also applied similar techniques to solar flares, using
extreme ultraviolet irradiation time series.
Our final catalog contains ∼120000 flares on ∼14000 stars. Due to the
strict filtering and the final manual vetting, this sample contains
virtually no false positives, although at the expense of reduced
completeness. Using this flare catalog, we detected a dependence of
the average flare shape on the spectral type. These changes are not
apparent for individual flares; they only appear when averaging
thousands of events. We find no strong clustering in the flare shape
space. We have created new analytical flare templates for different
types of stars, and we present a technique to sample realistic flares
and a method to locate flares with similar shapes. The flare catalog
along with the extracted flare shapes and the data used to train
flatwrm2 are publicly available.
Description:
To search for stellar flares we used 2-min cadence Pre-search Data
Conditioning Simple Aperture Photometry (PDCSAP) light curves provided
by the Science Processing Operations Center pipeline (SPOC) from the
first five years of the TESS mission, up to sector 69.
We collected the following astrophysical parameters from version 8.2
of the TESS Input Catalog (TIC; Stassun et al., 2019AJ....158..138S 2019AJ....158..138S,
cat. IV/38): effective temperature (Teff), surface gravity (logg),
bolometric luminosity (Lbol), Gaia DR2 (Gaia Collaboration,
2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345) GBP-GRP color index, Gaia DR2
MG absolute G magnitude calculated from the observed G magnitude and
the parallax.
The stellar astrophysical parameters are presented in Table 2, and the
flare catalog is presented in Table 3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 63 15130 Astrophysical parameters of the flaring stars
table3.dat 66 121895 Final flare catalog
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 I10 --- TIC TIC identifier
12- 21 F10.7 mag Bp-Rp ? Gaia DR2 Bp-Rp colour index
23- 30 F8.5 mag GMAG ? Gaia DR2 absolute G magnitude
32- 40 E9.4 K Teff ? Effective temperature from TIC v8.2
42- 46 F5.3 [cm/s2] logg ? Surface density from TIC v8.2
48- 56 E9.4 10-7W LTESS ? TESS quiesent luminosity
58- 60 I3 --- Nflare [1/726] Number of flares
62- 63 I2 --- Nsect [1/35] Number of sector the target was
observed with 2-min cadence up to sector 69
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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- 10 I10 --- TIC TIC identifier
12- 13 I2 --- Sector [1/69] Sector number
15- 25 F11.6 d Tpeak Peak time
27- 33 F7.3 min TimeScale Time scale
35- 44 F10.5 --- Amp Amplitude
46- 56 F11.5 mm ED Equivalent duration
58- 66 E9.3 10-7J ETESS ? Flare energy in the TESS band
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History:
Copied at https://zenodo.org/records/14179313
(End) Patricia Vannier [CDS] 22-May-2025