J/A+A/668/A111 TRAPPIST-1 flares griz data (Maas+, 2022)
Lower-than-expected flare temperatures for TRAPPIST-1.
Maas A., Ilin E., Oshagh M., Palle E., Parviainen H., Molaverdikhani K.,
Quirrenbach A., Esparza-Borges E., Murgas F., Bejar V.J.S., Narita N.,
Fukui A., Lin C.-L., Mori M., Klagyivik P.
<Astron. Astrophys. 668, A111 (2022)>
=2022A&A...668A.111M 2022A&A...668A.111M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry, SDSS
Keywords: stars: flare - stars: activity - stars: individual: TRAPPIST-1 -
stars: low-mass - planets and satellites: atmospheres -
planet-star interactions
Abstract:
Stellar flares emit thermal and non-thermal radiation in the X-ray and
UV regime. Although high energetic radiation from flares is a
potential threat to exoplanet atmospheres and may lead to surface
sterilization, it might also provide the extra energy for low mass
stars needed to trigger and sustain prebiotic chemistry. Despite the
UV continuum emission being constrained partly by the flare
temperature, few efforts have been made to determine the flare
temperature for ultra-cool M-dwarfs. We investigate two flares on
TRAPPIST-1, an ultra-cool dwarf star that hosts seven exoplanets of
which three lie within its habitable zone. The flares are detected in
all four passbands of the MuSCAT2 instrument allowing a determination
of their temperatures and bolometric energies.
We analyze the light curves of the MuSCAT1 and MuSCAT2 instruments
obtained between 2016 and 2021 in g, r, i, zs-filters. We conduct an
automated flare search and visually confirmed possible flare events.
The black body temperatures are inferred directly from the spectral
energy distribution (SED) by extrapolating the filter-specific flux.
We study the temperature evolution, the global temperature, and the
peak temperature of both flares.Results. White-light M-dwarf flares
are frequently described in the literature by a black body with a
temperature of 9000-10000K. For the first time we infer effective
black body temperatures of flares that occurred on TRAPPIST-1. The
black body temperatures for the two TRAPPIST-1flares derived from the
SED are consistent with TSED=7940+430-390K and
TSED=6030+300-270K. The flare black body temperatures at the peak
are also calculated from the peak SED yielding
TSEDp=13620+1520-1220K and TSEDp=8290+660-550K. We update the
flare frequency distribution of TRAPPIST-1 and discuss the impacts of
lower black body temperatures on exoplanet habitability. Conclusions.
We show that for the ultra-cool M-dwarf TRAPPIST-1 the flare black
body temperatures associated with the total continuum emission are
lower and not consistent with the usually adopted assumption of
9000-10000K in the context of exoplanet research. For the peak
emission, both flares seem to be consistent with the typical range
from 9000-14000K, respectively. This could imply different and faster
cooling mechanisms. Further multi-colour observations are needed to
investigate whether our observations are a general characteristic of
ultra-cool M-dwarfs. This would have significant implications for the
habitability of exoplanets around these stars because the UV surface
flux is likely to be overestimated by the models with higher flare
temperatures.
Description:
The catalogue contains the used lightcurves for the two TRAPPIST-1
flares in every filter used in the paper. The flux is given in
normalized units and the time in RJD JD-2454833d. The cadence per
filter varies, usually z < i < r < g.
Objects:
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RA (2000) DE Designation(s)
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23 06 29.37 -05 02 29.0 TRAPPIST-1 = K2-112
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
flare1.dat 158 431 Flare 1 griz data
flare2.dat 158 694 Flare 2 griz data
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See also:
J/AJ/156/178 : NIR transmission spectra of TRAPPIST-1 planets (Zhang+, 2018)
J/AJ/156/218 : Transit light curves of TRAPPIST-1 planets (Ducrot+, 2018)
J/A+A/640/A112 : TRAPPIST-1 transit timings (Ducrot+, 2020)
J/A+A/650/A138 : TRAPPIST-1 analogue stars TESS light curves (Seli+, 2021)
J/A+A/658/A133 : TRAPPIST-1 h NIR spectrum (Gressier+, 2022)
J/A+A/658/A170 : TRAPPIST-1 best-fit parameters (Teyssandier+, 2022)
Byte-by-byte Description of file: flare1.dat flare2.dat
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Bytes Format Units Label Explanations
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1- 18 F18.13 d Timez Time for z band (JD-2454833)
20- 38 F19.16 --- Fluxz ? Flux in z band in normalized units
40- 58 F19.13 d Timei ? Time for i band (JD-2454833)
60- 78 F19.16 --- Fluxi ? Flux in i band in normalized units
80- 98 F19.13 d Timer ? Time for r band (JD-2454833)
100-118 F19.16 --- Fluxr ? Flux in r band in normalized units
120-138 F19.13 d Timeg ? Time for g band (JD-2454833)
140-158 F19.16 --- Fluxg ? Flux in g band in normalized units
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Acknowledgements:
Aaron Maas, aaron.wehlmann(at)gmail.com
(End) Patricia Vannier [CDS] 04-Oct-2022