Astronomy and Astrophysics, volume 434, 677-689 (2005/5-1)
Understanding B-type supergiants in the low metallicity environment of the SMC. II.
TRUNDLE C. and LENNON D.J.
Abstract (from CDS):
Despite a resurgence of effort over the last decade in the area of massive stars there is still ambiguity over their evolutionary path, contamination of their surface abundances and the behaviour of their stellar winds. Here 10 SMC B-type supergiants are analysed applying a unified model atmosphere code fastwind to intermediate resolution spectra from the ESO Multi Mode Instrument (emmi) on the NTT telescope. Combined with the 8 targets analysed in Paper I (Trundle et al., 2004A&A...417..217T), this work provides observational results on the properties of the winds and chemical compositions of B-type supergiants in the SMC. This paper emphasizes and substantiates the implications for stellar evolution from Paper I; that current theoretical models need to produce larger degrees of surface nitrogen enhancements at lower rotational velocities. In addition a significant discrepancy between theoretical and observed mass-loss rates is discussed which will have important implications for the rotational velocities obtained from stellar evolution calculations. Furthermore, an initial calibration of the wind-momentum luminosity relationship for B-type supergiants in a low metallicity environment (Z=0.004) is presented.