The β Pictoris Phenomenon in A-Shell Stars: Detection of Accreting Gas

Abstract

We present the results of an expanded survey of A-shell stars using IUE high-dispersion spectra and find accreting, circumstellar gas in the line of sight to nine stars, in addition to the previously identified β Pic, HR 10, and 131 Tau, which can be followed to between +70 and 100 km s-1 relative to the star. Two of the program stars, HD 88195 and HD 148283, show variable high-velocity gas. Given the small number of IUE spectra for our program stars, detection of high-velocity, accreting gas in 2/3 of the A-shell stars sampled indicates that accretion is an intrinsic part of the A-shell phenomenon and that β Pic is not unique among main-sequence A stars in exhibiting such activity. Our program stars, as a group, have smaller column densities of high-velocity gas and smaller near-IR excesses compared with β Pic. These features are consistent with greater central clearing of a remnant debris disk, compared with β Pic, and suggest that the majority of field A-shell stars are older than β Pic.