In this paper, we present the results from spectroscopic and photometric observations of the M-type flare star YZ CMi in the framework of the Optical and Infrared Synergetic Telescopes for Education and Research (OISTER) collaborations during the Transiting Exoplanet Survey Satellite (TESS) observation period. We detected 145 white-light flares from the TESS light curve and 4 H$\alpha$ flares from the OISTER observations performed between 2019-01-16 and 2019-01-18. Among them, 3 H$\alpha$ flares were associated with white-light flares. However, one of them did not show clear brightening in continuum; during this flare, the H$\alpha$ line exhibited blue-asymmetry which has lasted for $\sim 60$ min. The line of sight velocity of the blue-shifted component is $-80$ - $-100$ km s$^{-1}$. This suggests that there can be upward flows of chromospheric cool plasma even without detectable red/NIR continuum brightening. By assuming that the blue-asymmetry in H$\alpha$ line was caused by a prominence eruption on YZ CMi, we estimated the mass and kinetic energy of the upward-moving material to be $10^{16}$ - $10^{18}$ g and $10^{29.5}$ - $10^{31.5}$ erg, respectively. The estimated mass is comparable to expectations from the empirical relation between the flare X-ray energy and mass of upward-moving material for stellar flares and solar CMEs. In contrast, the estimated kinetic energy for the non-white-light flare on YZ CMi is roughly $2$ orders of magnitude smaller than that expected from the relation between flare X-ray energy and kinetic energy for solar CMEs. This could be understood by the difference in the velocity between CMEs and prominence eruptions.

中文翻译：

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带有 OISTER 和 TESS 的 M 矮耀斑星 YZ Canis Minoris 的时间分辨光谱和光度测量：非白光耀斑期间 Hα 线的蓝色不对称

在本文中，我们在凌日系外行星巡天卫星 (TESS) 观测期间，在光学和红外协同教育和研究望远镜 (OISTER) 合作框架内，展示了 M 型耀斑星 YZ CMi 的光谱和光度观测结果时期。我们从 TESS 光变曲线中检测到 145 个白光耀斑，从 2019 年 1 月 16 日至 2019 年 1 月 18 日之间进行的 OISTER 观测中检测到 4 个 H$\alpha$ 耀斑。其中，3个H$\alpha$耀斑与白光耀斑有关。然而，其中之一在连续谱中没有表现出明显的增亮；在这次耀斑期间，H$\alpha$ 线表现出蓝色不对称性，持续了 $\sim 60$ 分钟。蓝移分量的视线速度为 $-80$ - $-100$ km s$^{-1}$。这表明即使没有可检测到的红色/近红外连续谱增亮，也可能存在色球层冷等离子体的向上流动。假设 H$\alpha$ 线中的蓝色不对称是由 YZ CMi 上的日珥爆发引起的，我们估计向上移动材料的质量和动能为 $10^{16}$ - $10^{18 }$ g 和 $10^{29.5}$ - $10^{31.5}$ erg，分别。估计的质量与耀斑 X 射线能量与恒星耀斑和太阳 CME 向上移动物质质量之间的经验关系的预期相当。相比之下，YZ CMi 上非白光耀斑的估计动能比根据耀斑 X 射线能量与太阳 CME 动能之间的关系所预期的动能大约小 2 美元数量级。