Related papers: Semi-analytical formulas for the fundamental param…
We undertake an optical and ultraviolet spectroscopic analysis of a sample of 20 Galactic B0 - B5 supergiants of luminosity classes Ia, Ib, Iab and II. Fundamental stellar parameters are obtained from optical diagnostics and a critical…
Effective temperatures of early-type supergiants are important to test stellar atmosphere- and internal structure-models of massive and intermediate mass objects at different evolutionary phases. However, these Teff values are more or less…
BA-type supergiants show a high potential as versatile indicators for modern astronomy. The focus here is on the determination of accurate and precise atmospheric parameters for a sample of 35 Galactic BA-type supergiants. Some first…
We present optical studies of the physical and wind properties, plus CNO chemical abundances, of 25 O9.5-B3 Galactic supergiants. We employ non-LTE, line blanketed, extended model atmospheres, which provide a modest downward revision in the…
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…
The following parameters are determined for 63 Galactic supergiants in the solar neighbourhood: effective temperature Teff, surface gravity log g, iron abundance log e(Fe), microturbulent parameter Vt, mass M/Msun, age t and distance d. A…
We present angular diameters for 42 luminosity class I stars and 32 luminosity class II stars that have been interferometrically determined with the Palomar Testbed Interferometer. Derived values of radius and effective temperature are…
We use moderate-resolution optical spectrophotometry and the new MARCS stellar atmosphere models to determine the effective temperatures of 74 Galactic red supergiants. From these we find a new effective temperature scale that is…
We calculate the hydrogen and helium ionization in B[e] envelopes and explore their dependence on mass-loss and effective temperature. We also present simulated observations of the Halpha emission line and the C IV 1550 doublet, and study…
We present a simple model to describe the dark matter density, the gas density, and the gas temperature profiles of galaxy clusters. Analytical expressions for these quantities are given in terms of only five free parameters with a clear…
Semi-analytic models are a powerful tool for studying the formation of galaxies. However, these models inevitably involve a significant number of poorly constrained parameters that must be adjusted to provide an acceptable match to the…
Modern spectroscopic surveys combined with Gaia distances are enabling reliable estimates of fundamental parameters for hundreds of Galactic O-type stars and the full range of spectral types and luminosity classes. Here we provide updated,…
High resolution optical spectra of 57 Galactic B-type supergiant stars have been analyzed to determine their rotational and macroturbulent velocities. In addition, their atmospheric parameters (effective temperature, surface gravity and…
We establish an empirical effective temperature calibration of main sequence, luminosity class V to III B-type stars for the Delta a photometric system which was originally developed to detect magnetic chemically peculiar objects of the…
We present new determinations of bolometric corrections and effective temperature scales as a function of infrared and optical colors, using a large database of photometric observations of about 6500 Population II giants in Galactic…
This work describes a procedure to derive several fundamental parameters such as the effective temperature, surface gravity, equatorial rotational velocity and microturbulent velocity. In this work, we have written a numerical procedure in…
Blue supergiants (BSGs) are key objects for understanding the evolution of massive stars. However, discrepancies between theoretical predictions and empirical observations have opened up important questions yet to be answered. Studying…
Following Bi & Davidsen (1997), we perform one dimensional semi analytic simulations along the lines of sight to model the intergalactic medium (IGM). Since this procedure is computationally efficient in probing the parameter space -- and…
Context. Precise and accurate determinations of effective temperature and surface gravity are mandatory to derive reliable chemical abundances and fundamental parameters like distances, masses, radii, luminosities of OB stars. Aims.…
This work presents the determination of the effective temperature, gravity, metallicity, mass, luminosity and age of 27 young early-type stars, most of them in the age range 1-10 Myr, and three -suspected- hot companions of post-T Tauri…