Detection of Accreting, Circumstellar Gas in a lambda Bootis Star: 131 Tauri

Abstract

We present IUE high-dispersion spectra of the lambda Boo star, 131 Tau (HD 38545), confirming the presence of shell spectral features and also providing the first detection of accreting, circumstellar gas in the spectrum of a lambda Boo star. Accreting gas can be followed in the mid-UV Fe II transitions to +80 km s-1 relative to the star. Circumstellar material can be followed to +60 km s-1 relative to the star in Zn II and is detected, albeit with low S/N, in Si II, Al II, and C I. The IUE data for 131 Tau were compared with archival spectra of other lambda Boo stars with optical detections of narrow absorption features, which have previously been interpreted as signatures of circumstellar gas. We find that the circumstellar absorption in 131 Tau more closely resembles similar features that are routinely observed in beta Pic and recently detected in other field A-shell stars.