An analysis of STIS HST UV spectra of M 33 early B supergiants^*

¹ Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
² Departamento de Astrofísica, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez, s/n, 38071 La Laguna, Spain
³ Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA
⁴ Universitäts-Sternwarte München, Scheinerstr. 1, 81679 München, Germany

Corresponding author: M. A.  Urbaneja, maup@ll.iac.es

Received: 7 February 2002
Accepted: 4 March 2002

Abstract

We present terminal velocities of M 33 B-supergiants, obtained from STIS HST spectra as part of our programme to investigate the Wind Momentum – Luminosity Relationship (WLR) in the Local Group. Terminal velocities are derived from their , , and resonance lines in UV spectra. Comparing with IUE spectra of Galactic B-supergiants we found evidence of low metallicity in three of our objects. The terminal velocities are consistent with the corresponding values of Galactic stars, except for B-133. For this star we find a very large and a red component deeper than the blue one, that might be an indication of binarity. The average ratio between terminal and turbulent wind velocities is 0.25, well above the value found for Galactic stars.