High resolution spectroscopy of the R Coronae Borealis star, V854 Centauri, during a deep minimum

Abstract

The R Coronae Borealis star V854 Cen was observed at minimum light (V about 15) at high spectral resolution from 5480 to 7070 A. The spectrum consists of three components: a continuum devoid of photospheric lines, a collection of sharp emission lines of Sc II, Ti II, Y II, and Ba II, and broad emission lines of forbidden O I, forbidden N II, forbidden S II, H-alpha, Na D, and C2 Swan bands. A low resolution spectrum reveals additional lines of Ca II, forbidden C I, and other species. The sharp emission lines are considered to be chromospheric lines. The broad lines with a full width of 400-500 km/s come from an extended region with a temperature of about 7000 K, but an electron density of 50/cu cm or less. It is suggested that V854 Cen may be a bipolar nebula.