학술논문
Detailed cool star flare morphology with CHEOPS and TESS
Document Type
Working Paper
Author
Bruno, G.; Pagano, I.; Scandariato, G.; Florén, H. -G.; Brandeker, A.; Olofsson, G.; Maxted, P. F. L.; Fortier, A.; Sousa, S. G.; Sulis, S.; Van Grootel, V.; Garai, Z.; Boldog, A.; Kriskovics, L.; Szabó, M. Gy.; Gandolfi, D.; Alibert, Y.; Alonso, R.; Bárczy, T.; Navascues, D. Barrado; Barros, S. C. C.; Baumjohann, W.; Beck, M.; Beck, T.; Benz, W.; Billot, N.; Borsato, L.; Broeg, C.; Cameron, A. Collier; Csizmadia, Sz.; Cubillos, P. E.; Davies, M. B.; Deleuil, M.; Deline, A.; Delrez, L.; Demangeon, O. D. S.; Demory, B. -O.; Ehrenreich, D.; Erikson, A.; Farinato, J.; Fossati, L.; Fridlund, M.; Gillon, M.; Güdel, M.; Günther, M. N.; Heitzmann, A.; Helling, Ch.; Hoyer, S.; Isaak, K. G.; Kiss, L.; Lam, K. W. F.; Laskar, J.; Etangs, A. Lecavelier des; Lendl, M.; Magrin, D.; Mordasini, C.; Nascimbeni, V.; Ottensamer, R.; Pallé, E.; Peter, G.; Piotto, G.; Pollacco, D.; Queloz, D.; Ragazzoni, R.; Rando, N.; Ratti, F.; Rauer, H.; Ribas, I.; Santos, N. C.; Sarajlic, M.; Ségransan, D.; Simon, A. E.; Singh, V.; Smith, A. M. S.; Stalport, M.; Thomas, N.; Udry, S.; Ulmer, B.; Venturini, J.; Villaver, E.; Walton, N. A.; Wilson, T. G.
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Subject
Language
Abstract
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 UV 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. We developed dedicated software for this purpose. Results. Multi-peak flares represent a significant percentage ($\gtrsim 30$\%) 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-peak 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 quasi-periodic pulsations 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 will help in this respect.
Comment: 28 pages, 25 figures, 4 tables, to be published in Astronomy & Astrophysics
Comment: 28 pages, 25 figures, 4 tables, to be published in Astronomy & Astrophysics