تقرير
Fast optical flares from M dwarfs detected by a one-second-cadence survey with Tomo-e Gozen
| العنوان: | Fast optical flares from M dwarfs detected by a one-second-cadence survey with Tomo-e Gozen |
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| المؤلفون: | Aizawa, Masataka, Kawana, Kojiro, Kashiyama, Kazumi, Ohsawa, Ryou, Kawahara, Hajime, Naokawa, Fumihiro, Tajiri, Tomoyuki, Arima, Noriaki, Jiang, Hanchun, Hartwig, Tilman, Fujisawa, Kotaro, Shigeyama, Toshikazu, Arimatsu, Ko, Doi, Mamoru, Kasuga, Toshihiro, Kobayashi, Naoto, Kondo, Sohei, Mori, Yuki, Okumura, Shin-ichiro, Takita, Satoshi, Sako, Shigeyuki |
| سنة النشر: | 2022 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics |
| الوصف: | We report a one-second-cadence wide-field survey for M-dwarf flares using the Tomo-e Gozen camera mounted on the Kiso Schmidt telescope. We detect 22 flares from M3-M5 dwarfs with rise times and amplitudes ranging from $5\, \mathrm{sec} \lesssim t_\mathrm{rise} \lesssim 100\,\mathrm{sec}$ and $0.5 \lesssim \Delta F/F_{\star} \lesssim 20$, respectively. The flare light curves mostly show steeper rises and shallower decays than those obtained from the Kepler one-minute cadence data and tend to have flat peak structures. Assuming a blackbody spectrum with temperatures of $9,000-15,000\,\mathrm{K}$, the peak luminosities and bolometric energies are estimated to be $10^{29}\,\mathrm{erg\,sec^{-1}} \lesssim L_\mathrm{peak} \lesssim 10^{31}\,\mathrm{erg\,sec^{-1}}$ and $10^{31}\,\mathrm{erg} \lesssim E_{\rm bol} \lesssim 10^{34}\,\mathrm{erg}$, which constitutes the bright end of fast optical flares for M dwarfs. We confirm that more than 90\% of the host stars of the detected flares are magnetically active based on their H$\alpha$ emission line intensities obtained by LAMOST. The estimated occurrence rate of the detected flares is $\sim 0.7$ per day per an active star, indicating they are common in magnetically active M dwarfs. We argue that the flare light curves can be explained by the chromospheric compression model; the rise time is broadly consistent with the Alfv\'en transit time of a magnetic loop with a length scale of $l_\mathrm{loop} \sim 10^4\,\mathrm{km}$ and a field strength of $1,000\,\mathrm{G}$, while the decay time is likely determined by the radiative cooling of the compressed chromosphere down to near the photosphere with a temperature of $\gtrsim 10,000\,\mathrm{K}$. These flares from M dwarfs could be a major contamination source for a future search of fast optical transients of unknown types. Comment: 39 pages, 13 figures, accepted for publication in PASJ |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1093/pasj/psac056 |
| URL الوصول: | http://arxiv.org/abs/2206.12847 |
| رقم الأكسشن: | edsarx.2206.12847 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1093/pasj/psac056 |
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