Flaring-associated Complex Dynamics in Two M-dwarfs Revealed by Fast, Time-resolved Spectroscopy. (arXiv:2206.10412v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Wang_J/0/1/0/all/0/1">J. Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_H/0/1/0/all/0/1">H. L. Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Xin_L/0/1/0/all/0/1">L. P. Xin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_G/0/1/0/all/0/1">G. W. Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bai_J/0/1/0/all/0/1">J. Y. Bai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gao_C/0/1/0/all/0/1">C. Gao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ren_B/0/1/0/all/0/1">B. Ren</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Song_D/0/1/0/all/0/1">D. Song</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Deng_J/0/1/0/all/0/1">J. S. Deng</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Han_X/0/1/0/all/0/1">X. H. Han</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dai_Z/0/1/0/all/0/1">Z. G. Dai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liang_E/0/1/0/all/0/1">E. W. Liang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_X/0/1/0/all/0/1">X. Y. Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wei_J/0/1/0/all/0/1">J. Y. Wei</a>

Habitability of an exoplanet is believed to be profoundly affected by
activities of the host stars, although the related coronal mass ejections
(CMEs) are still rarely detected in solar-like and late-type stars. We here
report an observational study on flares of two M-dwarfs triggered by the
high-cadence survey performed by the Ground Wide-angle Camera system. In both
events, the fast, time-resolved spectroscopy enables us to identify symmetric
broad H$alpha$ emission with not only a nearly zero bulk velocity, but also a
large projected maximum velocity as high as $sim700-800 mathrm{km s^{-1}}$.
This broadening could be resulted from either Stark (pressure) effect or a
flaring-associated CME at stellar limb. In the context of the CME scenario, the
CME mass is estimated to be $sim4times10^{18}$ g and $2times10^{19}$ g. In
addition, our spectral analysis reveals a temporal variation of the line center
of the narrow H$alpha$ emission in both events. The variation amplitudes are
at tens of $mathrm{km s^{-1}}$, which could be ascribed to the chromospheric
evaporation in one event, and to a binary scenario in the other one. With the
total flaring energy determined from our photometric monitor, we show a
reinforced trend in which larger the flaring energy, higher the CME mass is.

Habitability of an exoplanet is believed to be profoundly affected by
activities of the host stars, although the related coronal mass ejections
(CMEs) are still rarely detected in solar-like and late-type stars. We here
report an observational study on flares of two M-dwarfs triggered by the
high-cadence survey performed by the Ground Wide-angle Camera system. In both
events, the fast, time-resolved spectroscopy enables us to identify symmetric
broad H$alpha$ emission with not only a nearly zero bulk velocity, but also a
large projected maximum velocity as high as $sim700-800 mathrm{km s^{-1}}$.
This broadening could be resulted from either Stark (pressure) effect or a
flaring-associated CME at stellar limb. In the context of the CME scenario, the
CME mass is estimated to be $sim4times10^{18}$ g and $2times10^{19}$ g. In
addition, our spectral analysis reveals a temporal variation of the line center
of the narrow H$alpha$ emission in both events. The variation amplitudes are
at tens of $mathrm{km s^{-1}}$, which could be ascribed to the chromospheric
evaporation in one event, and to a binary scenario in the other one. With the
total flaring energy determined from our photometric monitor, we show a
reinforced trend in which larger the flaring energy, higher the CME mass is.

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