Resonance line profiles in A type supergiants from IUE and Copernicus spectra.

Abstract

A comparative study of UV resonance line profiles in one F0 type and four A type supergiants is made from a set of IUE spectra; the O I, C I, C II, Mg II, Al II, Al III, Si II, P II and Fe II ions are considered. Alpha Cyg (A 2 Ia) shows the most prominent velocity field effects on the profiles: they are broadened, asymmetric and shifted up to 240 km/s at the blue edge with a very sharp blue wing. HR 1040 (A 0 Ia) and HR 2874 (A 5 Ib) present the same phenomena to a lesser degree, Mg II resonance being split in two blueshifted components in both stars. The stars Eta Leo and Alpha Car, both Ib, exhibit no evidence for mass outflow, while the mass loss rate for Alpha Cyg is estimated at between 1.1 x 10 to the -8th and 7 x 10 to the -8th solar masses/yr.