Exocomet signatures around the A-shell star $\Phi$ Leo?

Abstract

We present an intensive monitoring of high-resolution spectra of the Ca {\sc ii} K line in the A7IV shell star $\Phi$ 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 $\beta$ 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 $\Phi$ Leo. To our knowledge, with the exception of $\beta$ 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 $\Phi$ Leo presents the richest environment with comet-like events known to date, second only to $\beta$ Pic.

A&A letters, proof-corrected

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• Debris Disk Evolution Around A Stars
• The Structure of the Local Interstellar Medium V: Electron Densities
• The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets
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Cited by in corpus (6)

• Exocomets from a Solar System Perspective
• TESS observations of Be stars: a new interpretation
• Atomic Gas in Debris Discs
• An Incipient Debris Disk in the Chamaeleon I Cloud
• The A-shell star Phi Leo revisited: its photospheric and circumstellar spectra
• Theoretical Studies of Comets in the 55 Cancri System