Vol. 594
In section 1. Letters to the Editor

Exocomet signatures around the A-shell star φ Leonis?

by C. Eiroa, I. Rebollido, B. Montesinos, et al. A&A 594, L1


About thirty years ago, an extended debris disk was seen for the first time around β Pictoris, a magnitude 3.7, A6V type, young star. Ten years later, changes in the calcium and potassium spectral lines of the star were discovered and shown to be evidence for the evaporation of exocomets in that system. This led to the prediction of the existence of a massive planet in that system. In 2010, a giant planet was imaged directly in the disk of β Pic. Eiroa et al. study a very similar bright A7IV star, φ Leo, of magnitude 4.5 that is known to be seen edge-on. φ Leo is, however significantly older (500-900Myr) than β Pic (~20 Myr). They detect a rich variety of comet-like signatures in the Ca and K spectral lines, raising several questions: Why are comets still seen frequently in this relatively old system? What sends them close to the star? It will be extremely interesting to pursue the analysis, both to determine whether an imbalance of blue-shifted to red-shifted signatures may betray the presence of an eccentric planet, and to directly image this system.