Related papers: Extragalactic Supergiants
Blue supergiants of spectral types B and A are the visually brightest stars in spiral and irregular galaxies, with their most luminous members (at M_V=-10) outshining entire dwarf galaxies. This characteristic allows us to use them as…
Blue supergiant stars can be exceptionally bright objects in the optical, making them prime targets for the determination of extragalactic distances. I describe how their photometric and spectroscopic properties can be calibrated to provide…
The present generation of large telescopes facilitates spectroscopy of blue supergiants in galaxies out to distances beyond the Local Group. Recent developments in NLTE spectrum synthesis techniques allow for an accurate determination of…
Because of their enormous intrinsic brightness blue supergiants are ideal stellar objects to be studied spectroscopically as individuals in galaxies far beyond the Local Group. Quantitative spectroscopy by means of efficient multi-object…
Measuring distances to galaxies, determining their chemical composition, investigating the nature of their stellar populations and the absorbing properties of their interstellar medium are fundamental activities in modern extragalactic…
A-type supergiants are primary targets for quantitative spectroscopy of individual stars in nearby galaxies because of their intrinsic brightness. An overview is given on the non-LTE techniques required for their analysis. Applications…
A supergiants are objects in transition from the blue to the red (and vice versa) in the uppermost HRD. They are the intrinsically brightest "normal" stars at visual light with absolute visual magnitudes up to -9. They are ideal to study…
Blue Supergiants (BSGs) are the brightest stars in the universe at visual light with absolute magnitudes up to Mv=-10 mag. They are ideal stellar objects for the determination of extragalactic distances, in particular, because the perennial…
An overview is presented of the recent advances in understanding the B[e] phenomenon among blue supergiant stars in light of high-angular resolution observations and with an emphasis on the results obtained by means of long baseline optical…
Massive BA-type supergiants are among the visually brightest stars in galaxies with active star formation. As such they are versatile tools for studies of stellar and galactochemical evolution. Moreover, they can act as distance indicators…
Despite their paucity, massive hot stars are real cosmic engines of fundamental importance in shaping our Universe, from its very early stages up to its current appearance. Understanding the physics of massive stars is then a key issue for…
We review recent advances in our understanding of massive stars through the analysis of their spectra. Improvements in model atmospheres and analysis methods are briefly discussed. Results obtained for stars in the Local Group are compared…
Observational manifestations of far evolved stars at the asymptotic giants branch and their nearest descendants are briefly considered. Main results of their chemical composition determinations based on long term high resolution…
Cool red giants and supergiants are among the most complex and fascinating stars in the Universe. They are bright and large, and thus can be observed to enormous distances allowing us to study the properties of their host galaxies, such as…
Stellar evolution theory is most uncertain for massive stars. For reliable predictions of the evolution of massive stars and their final fate, solid constraints on the physical parameters, and their changes along the evolution and in…
B[e] stars are among the most peculiar objects in the sky. This spectral type, characterised by allowed and forbidden emission lines, and a large infrared excess, does not represent an homogenous class of objects, but instead, a mix of…
Blue straggler stars are unique main-sequence stars that appear more luminous, hotter, and therefore younger, than their coeval counterparts. In star clusters, these stars are located above the cluster turn-off in the Hertzsprung-Russell…
Multi-object spectroscopic observations of blue supergiants in NGC 3621, a spiral galaxy at a distance of 6.7 Mpc, carried out with the ESO VLT and FORS are presented. We demonstrate the feasibility of quantitative stellar spectroscopy at…
Almost all massive stars explode as supernovae and form a black hole or neutron star. The remnant mass and the impact of the chemical yield on subsequent star formation and galactic evolution strongly depend on the internal physics of the…
Regular intrinsic brightness variations observed in many stars are caused by pulsations. These pulsations provide information on the global and structural parameters of the star. The pulsation periods range from seconds to years, depending…