Clumpy accretion onto pre-main-sequence stars

Abstract

Medium-resolution spectroscopic observations covering the range 5150-9100 A are made of five premain-sequence stars in the Corona Australis star-forming region. They are the known variable stars R CrA, S CrA, T CrA, TY CrA, and VV CrA. During the week of observation significant changes, sometimes occurring between successive nights, were observed in the spectra of R CrA and S CrA. They are interpreted as being due to variable accretion onto the star. Velocities are measured confirming that the photosphere of R CrA in this region of the spectrum is invisible. Photospheric absorption lines are observed in S CrA, T CrA, and TY CrA. In VV CrA only Li I lambda-6708 is detected. The velocity variation of TY CrA is demonstrated. An infrared image of VV CrA is reproduced which shows the infrared companion 1.9 arcsec NE of the primary star.