Monday, December 19, 2016

Exocomet signatures around the A-shell star Φ Leo?


Eiroa et al


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 term (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 of the ones observed towards the debris disk host star β Pic, which are usually 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 is the one with the best time resolution at the mentioned timescales done on a star with events attributed to exocomets. Assuming the cometary scenario, and considering the timescales of our monitoring, our results point to Φ Leo presenting the richest environment with comet-like events yet known, second only to β Pic.

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