A壳层恒星$Φ$狮子座周围的彗星特征？
Exocomet signatures around the A-shell star $Φ$ Leo?
摘要：
我们提出了一个密集的监测高分辨率光谱的Ca { \sc ii} K线在A7 IV壳星$Φ$狮子座在很短的时间（分钟，小时），短（夜到夜），和中等（周，月）的时间尺度。光谱在小时、天和月的时间尺度上显示出显著的变化。这些零星事件的特征与大多数在碎片盘宿主恒星$β$ Pic观测到的非常相似，通常被解释为固体蒸发的迹象，彗星状的物体擦过或落在恒星上。因此，我们的研究结果表明，固体的存在$Φ$狮子座周围。据我们所知，除了$β$ Pic，我们的监测在上述时间尺度上具有最好的时间分辨率，用于发生系外彗星事件的恒星。假设彗星的情况下，并考虑到我们的监测时间尺度，我们的结果表明，$Φ$狮子座提出了最丰富的环境与彗星一样的事件，迄今为止，仅次于$β$ Pic。
英文摘要：
We present an intensive monitoring of high-resolution spectra of the Ca {\sc ii} K line in the A7IV shell star $Φ$ Leo at very short (minutes, hours), short (night to night), and medium (weeks, months) timescales. The spectra show remarkable variable absorptions on timescales of hours, days, and months. The characteristics of these sporadic events are very similar to most that are observed toward the debris disk host star $β$ Pic, which are commonly interpreted as signs of the evaporation of solid, comet-like bodies grazing or falling onto the star. Therefore, our results suggest the presence of solid bodies around $Φ$ Leo. To our knowledge, with the exception of $β$ Pic, our monitoring has the best time resolution at the mentioned timescales for a star with events attributed to exocomets. Assuming the cometary scenario and considering the timescales of our monitoring, our results indicate that $Φ$ Leo presents the richest environment with comet-like events known to date, second only to $β$ Pic.
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