论文标题
在年轻的太阳能恒星Ek Draconis上发现了长期的超氟，h $α$和白光排放的时间几乎相似
Discovery of a Long-Duration Superflare on a Young Solar-Type Star EK Draconis with Nearly Similar Time Evolution for H$α$ and White-Light Emissions
论文作者
论文摘要
众所周知，年轻的太阳能型恒星会显示出频繁的“超级弹药”，这可能会严重影响年轻行星的可居住世界，并通过强烈的辐射和冠状质量弹出。在这里，我们报告了对年轻的太阳能型明星Ek Draconis（50-120 Myr Age）的长期超级荧光的光学光谱和光度观察，其中包括Seimei望远镜和$ Transing $ $ $ $ $ $ $ exoplanet $ $ $ $ $ $ usize $ sublise $ $ satellite $ satellite $（$ tess $）。耀斑能量2.6 $ \ times $ 10 $^{34} $ ERG和白色光明持续时间2.2小时比最大的太阳能耀斑大得多，这是由光谱检测到的太阳能型明星上最大的超弹力。 H $α$排放概况没有显着的线不对称，这意味着没有丝状喷发的签名，这与以前对这颗恒星的超级面前的检测不同（Namekata etal。2021，$ nat.astron $）。同样，它没有显示出明显的线扩展，表明耀斑脚点的非热加热不是必不可少的，或者脚步在肢体后面。 H $α$耀斑的时间演变和持续时间与白光耀斑的时间相同，这与一般的M-dwarf（Super-）耀斑和太阳耀斑不同。这种出乎意料的时间演化可能表明，与一般太阳耀斑相比，不同的辐射机制是主要的，如下所示：（1）辐射（非LIMB）火炬回路，（2）（2）通过辐射回压重新辐射，在这两种情况下，在这两种情况下都可以确定h $ a $ a $α$α$α$α$α$α$α$α$α$α$α$α$α$和白色的时标。
Young solar-type stars are known to show frequent "superflares", which may severely influence the habitable worlds on young planets via intense radiations and coronal mass ejections. Here we report an optical spectroscopic and photometric observation of a long-duration superflare on the young solar-type star EK Draconis (50-120 Myr age) with the Seimei telescope and $Transiting$ $Exoplanet$ $Survey$ $Satellite$ ($TESS$). The flare energy 2.6$\times$10$^{34}$ erg and white-light flare duration 2.2 hr are much larger than those of the largest solar flares, and this is the largest superflare on a solar-type star ever detected by optical spectroscopy. The H$α$ emission profile shows no significant line asymmetry, meaning no signature of a filament eruption, unlike the only previous detection of a superflare on this star (Namekata et al. 2021, $Nat.Astron$). Also, it did not show significant line broadening, indicating that the non-thermal heating at the flare footpoints are not essential or that the footpoints are behind the limb. The time evolution and duration of the H$α$ flare are surprisingly almost the same as those of the white-light flare, which is different from general M-dwarf (super-)flares and solar flares. This unexpected time evolution may suggest that different radiation mechanisms than general solar flares are predominant, as follows: (1) radiation from (off-limb) flare loops, and (2) re-radiation via radiative backwarming, in both of which the cooling timescales of flare loops could determine the timescales of H$α$ and white light.
