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

TL;DR

This study monitors the Ca II K line in star $$ Leo, revealing variable absorption events similar to exocomet signatures observed in other debris disk stars, suggesting the presence of solid bodies around the star.

Contribution

First intensive, high-resolution spectral monitoring of $$ Leo across multiple timescales, revealing exocomet-like activity with unprecedented temporal resolution for this star.

Findings

Variable absorption events similar to exocomet signatures.

$$ Leo hosts the most frequent exocomet-like events after $eta$ Pic.

Star shows a rich environment of solid bodies inferred from spectral variability.

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.