Issue |
A&A
Volume 686, June 2024
|
|
---|---|---|
Article Number | A239 | |
Number of page(s) | 27 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361/202348951 | |
Published online | 18 June 2024 |
Detailed cool star flare morphology with CHEOPS and TESS*,**,***
1
INAF, Osservatorio Astrofisico di Catania,
Via S. Sofia 78,
95123
Catania,
Italy
e-mail: giovanni.bruno@inaf.it
2
Department of Astronomy, Stockholm University, AlbaNova University Center,
10691
Stockholm,
Sweden
3
Astrophysics Group, Lennard Jones Building, Keele University,
Staffordshire,
ST5 5BG,
UK
4
Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern,
Gesellschaftsstrasse 6,
3012
Bern,
Switzerland
5
Center for Space and Habitability, University of Bern,
Gesellschaftsstrasse 6,
3012
Bern,
Switzerland
6
Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas,
4150-762
Porto,
Portugal
7
Aix Marseille Univ., CNRS, CNES, LAM,
38 rue Frédéric Joliot-Curie,
13388
Marseille,
France
8
Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège,
Allée du 6 Août 19C,
4000
Liège,
Belgium
9
HUN-REN-ELTE Exoplanet Research Group,
9700
Szombathely,
Szent Imre, h. u. 112,
Hungary
10
ELTE Gothard Astrophysical Observatory,
9700
Szombathely,
Szent Imre, h. u. 112,
Hungary
11
Astronomical Institute, Slovak Academy of Sciences,
05960
Tatranská Lomnica,
Slovakia
12
Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences,
Konkoly Thege út 15-17.,
1121
Budapest,
Hungary
13
CSFK, MTA Centre of Excellence,
Konkoly Thege út 15-17.,
1121
Budapest,
Hungary
14
Dipartimento di Fisica, Università degli Studi di Torino,
via Pietro Giuria 1,
10125
Torino,
Italy
15
Instituto de Astrofísica de Canarias, Vía Láctea s/n,
38200
La Laguna, Tenerife,
Spain
16
Departamento de Astrofísica, Universidad de La Laguna, Astrofísico Francisco Sanchez s/n,
38206
La Laguna, Tenerife,
Spain
17
Admatis,
5. Kandó Kálmán Street,
3534
Miskolc,
Hungary
18
Depto. de Astrofísica, Centro de Astrobiología (CSIC-INTA), ESAC campus,
28692
Villanueva de la Cañada (Madrid),
Spain
19
Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre,
4169-007
Porto,
Portugal
20
Space Research Institute, Austrian Academy of Sciences,
Schmiedlstrasse 6,
8042
Graz,
Austria
21
Observatoire astronomique de l’Université de Genève,
Chemin Pegasi 51,
1290
Versoix,
Switzerland
22
INAF, Osservatorio Astronomico di Padova,
Vicolo dell’Osservatorio 5,
35122
Padova,
Italy
23
Centre for Exoplanet Science, SUPA School of Physics and Astronomy, University of St Andrews, North Haugh,
St Andrews
KY16 9SS,
UK
24
Institute of Planetary Research, German Aerospace Center (DLR),
Rutherfordstrasse 2,
12489
Berlin,
Germany
25
INAF, Osservatorio Astrofisico di Torino,
Via Osservatorio, 20,
10025
Pino Torinese To,
Italy
26
Centre for Mathematical Sciences, Lund University,
Box 118,
221 00
Lund,
Sweden
27
Astrobiology Research Unit, Université de Liège,
Allée du 6 Août 19C,
4000
Liège,
Belgium
28
Institute of Astronomy, KU Leuven,
Celestijnenlaan 200D,
3001
Leuven,
Belgium
29
Centre Vie dans l’Univers, Faculté des sciences, Université de Genève,
Quai Ernest-Ansermet 30,
1211 Genève 4,
Switzerland
30
Leiden Observatory, University of Leiden,
PO Box 9513,
2300
RA Leiden,
The Netherlands
31
Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory,
439 92
Onsala,
Sweden
32
Department of Astrophysics, University of Vienna,
Türkenschanzstrasse 17,
1180
Vienna,
Austria
33
European Space Agency (ESA), European Space Research and Technology Centre (ESTEC),
Keplerlaan 1,
2201
AZ
Noordwijk,
The Netherlands
34
Institute for Theoretical Physics and Computational Physics, Graz University of Technology,
Petersgasse 16,
8010
Graz,
Austria
35
Konkoly Observatory, Research Centre for Astronomy and Earth Sciences,
1121
Budapest,
Konkoly Thege Miklós út 15-17,
Hungary
36
ELTE Institute of Physics,
Pázmány Péter sétány 1/A,
1117
Budapest,
Hungary
37
IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ., Sorbonne Univ.,
77 av. Denfert-Rochereau,
75014
Paris,
France
38
Institut d’astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie,
98bis bd. Arago,
75014
Paris,
France
39
Institute of Optical Sensor Systems, German Aerospace Center (DLR),
Rutherfordstrasse 2,
12489
Berlin,
Germany
40
Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università degli Studi di Padova,
Vicolo dell’Osservatorio 3,
35122
Padova,
Italy
41
Department of Physics, University of Warwick,
Gibbet Hill Road,
Coventry
CV4 7AL,
UK
42
ETH Zurich, Department of Physics,
Wolfgang-Pauli-Strasse 2,
8093
Zurich,
Switzerland
43
Cavendish Laboratory,
JJ Thomson Avenue,
Cambridge
CB3 0HE,
UK
44
Institut fuer Geologische Wissenschaften, Freie Universitaet Berlin,
Maltheserstrasse 74-100,
12249
Berlin,
Germany
45
Institut de Ciencies de l’Espai (ICE, CSIC), Campus UAB, Can Magrans s/n,
08193
Bellaterra,
Spain
46
Institut d’Estudis Espacials de Catalunya (IEEC),
Gran Capità 2-4,
08034
Barcelona,
Spain
47
Institute of Astronomy, University of Cambridge,
Madingley Road,
Cambridge,
CB3 0HA,
UK
Received:
13
December
2023
Accepted:
11
March
2024
Context. White-light stellar flares are proxies for some of the most energetic types of flares, but their triggering mechanism is still poorly understood. As they are associated with strong X and ultraviolet emission, their study is particularly relevant to estimate the amount of high-energy irradiation onto the atmospheres of exoplanets, especially those in their stars’ habitable zone.
Aims. We used the high-cadence, high-photometric capabilities of the CHEOPS and TESS space telescopes to study the detailed morphology of white-light flares occurring in a sample of 130 late-K and M stars, and compared our findings with results obtained at a lower cadence.
Methods. We employed dedicated software for the reduction of 3 s cadence CHEOPS data, and adopted the 20 s cadence TESS data reduced by their official processing pipeline. We developed an algorithm to separate multi-peak flare profiles into their components, in order to contrast them to those of single-peak, classical flares. We also exploited this tool to estimate amplitudes and periodicities in a small sample of quasi-periodic pulsation (QPP) candidates.
Results. Complex flares represent a significant percentage (≳30%) of the detected outburst events. Our findings suggest that high-impulse flares are more frequent than suspected from lower-cadence data, so that the most impactful flux levels that hit close-in exoplanets might be more time-limited than expected. We found significant differences in the duration distributions of single and complex flare components, but not in their peak luminosity. A statistical analysis of the flare parameter distributions provides marginal support for their description with a log-normal instead of a power-law function, leaving the door open to several flare formation scenarios. We tentatively confirmed previous results about QPPs in high-cadence photometry, report the possible detection of a pre-flare dip, and did not find hints of photometric variability due to an undetected flare background.
Conclusions. The high-cadence study of stellar hosts might be crucial to evaluate the impact of their flares on close-in exoplanets, as their impulsive phase emission might otherwise be incorrectly estimated. Future telescopes such as PLATO and Ariel, thanks to their high-cadence capability, will help in this respect. As the details of flare profiles and of the shape of their parameter distributions are made more accessible by continuing to increase the instrument precision and time resolution, the models used to interpret them and their role in star-planet interactions might need to be updated constantly.
Key words: methods: data analysis / techniques: photometric / stars: activity / stars: flare / planetary systems
The CHEOPS photometry discussed in this paper is available in electronic form at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/686/A239.
This study used CHEOPS data observed as part of the Guaranteed Time Observation programmes CH_PR100018 (PI: I. Pagano) and CH_PR100010 (PI: G. Szabó).
The main parts of the code we developed can be found on GitHub (https://github.com/giovbruno/flarefinder).
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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