Variable Radio Sources in the Corona Australis Cloud

Abstract

The radio continuum emission from pre-main-sequence stars in the Corona Australis star formation region has been studied over the period 1985-1992 using the Very Large Array (VLA) and the Australia Telescope. One source, IRS 5, shows significant long- and short-term variability, while another, Radio Source 5 of Brown [ApJL, 332, L3 1(1987)], is possibly variable. Radio emission is detected from the T Tauri star S CrA. During 1992 IRS 5 underwent a major radio outburst, when the flux increased to over ten times its mean quiescent value. During the period of high emission, the flux was stable over time periods of less than 24 h, in contrast with the radio outburst of another young star, DoAr 21 [Feigelson & Montmerle, ApJL, 289, L19 (1985)]. The spectra of all three objects studied appear consistent with a thermal emission process, and that of IRS 1 may be from an optically thick region.