High-resolution UCLES/AAT spectra are presented for nine B-type supergiants in the SMC, chosen on the basis that they may show varying amounts of nuclear-synthetically processed material mixed to their surface. These spectra have been analysed using a new grid of approximately 12 000 non-LTE line blanketed TLUSTY model atmospheres to estimate atmospheric parameters and chemical composition. The...

We present a combined analysis of the kinematics of the Large Magellanic Cloud through its H I gas, carbon stars, and red supergiant stars. After correcting the line-of-sight velocities for the recent accurate measurement of the LMC’s space motion, we find that each kinematic tracer clearly defines a flat rotation curve with similar shape but different amplitude for each tracer: 61 km s for the...

The problem of the classification of metal poor stars, such as occur in the Small Magellanic Cloud (SMC), is discussed with reference to the applicability of the MK system in such an environment. An alternative method is presented here and applied to B-type supergiants in the SMC. A local reference system is first devised and then a transformation to MK spectral types is determined by comparing...

Physical and wind properties of Galactic B supergiants are presented based upon non-LTE line blanketed model atmospheres, including Sher 25 toward the NGC 3603 cluster. We compare Hα derived wind densities with recent results for SMC B supergiants and generally confirm theoretical expectations for stronger winds amongst Galactic supergiants. Mid B supergiant winds are substantially weaker than ...

We analyze STIS spectra in the 1150-1700 Å wavelength range obtained for six early B supergiants in the neighboring galaxy M31. Because of their likely high (nearly solar) abundance, these stars were originally chosen to be directly comparable to their Galactic counterparts, and represent a much-needed addition to our current sample of B-type supergiants, in our efforts to study the dependence ...

Massive stars are the cosmic engines that shape and drive our Universe. Many issues such as their formation, their stability and the mass loss effects, are far from being completely understood. Recent ground-based and space observations have shown pulsations in massive MS and post-MS stars, such as acoustic and gravity modes excited by the κ-mechanism and even solar-like oscillations. Theoretic...

ASTRONOMY AND ASTROPHYSICS Study of an unbiased sample of B stars observed with Hipparcos: the discovery of a large amount of new Slowly Pulsating B Stars Abstract. We present a classiication of 267 new variable B-type stars discovered by Hipparcos. We have used two diierent classiication schemes and they both result in only a few new Cephei stars, a huge number of new Slowly Pulsating B stars,...

We discuss an interesting feature of the distribution of luminous blue variables (LBVs) on the H-R diagram, and we propose a connection with the bistability jump seen in the winds of earlytype supergiants. There appears to be a deficiency of quiescent LBVs on the S Doradus instability strip at luminosities between log(L/L⊙)≃ 5.6 and 5.8. The upper boundary, interestingly, is also where the temp...

Luminosities and effective temperatures are calculated for 17 nonvariable yellow giants and supergiants and nine Cepheids which were previously identified as members of open clusters. These stars are identified as being in the helium core burning stage of evolution. A comparison with the predictions of pulsation theory does not show any disagreement. O n the other hand, several comparisons with...

We present new calibrations of stellar parameters of O stars at solar metallicity taking non-LTE, wind, and line-blanketing effects into account. Gravities and absolute visual magnitudes are derived from results of recent spectroscopic analyses. Two types of effective temperature scales are derived: one from a compilation based on recent spectroscopic studies of a sample of massive stars – the ...