Related papers: Extragalactic Supergiants
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…
Blue compact galaxies are compact objects that are dominated by intense star formation. Most of them have dramatically different properties compared to the Milky Way and many other nearby galaxies. Using the IRAS, HI data, and optical…
We adopt a new approach to explore the puzzling nature of faint blue field galaxies. Instead of assuming that the local luminosity function is well defined, we first determine whether any non-evolving set of luminosity functions for…
Many stars -- if they could be imaged with enough angular resolution -- would exhibit features expected from theory but not possible to extract from spectra. We may group these by increasing complexity as follows. First, smooth variations…
We present a study of the photometric variability of spectroscopically confirmed supergiants in NGC 300, comprising 28 epochs extending over a period of five months. We find 15 clearly photometrically variable blue supergiants in a sample…
Luminous Fast Blue Optical Transients (LFBOTs) are a class of extragalactic transient of uncertain origin. Several hypotheses have been put forward which could feasibly be consistent with the sample number of events discovered thus far,…
Our understanding of large amplitude pulsating stars and their status in stellar evolution is briefly reviewed. The paper then describes the near-infrared light curves of various asymptotic giant branch stars, concentrating on possible…
Massive stars are at the core of our observations of the Universe up to the reionization epoch, both through their intense ionizing fluxes and through the energetic end products that release fresh elements into the interstellar medium. Our…
There is evidence that some red supergiants (RSGs) experience short lived phases of extreme mass loss, producing copious amounts of dust. These episodic outburst phases help to strip the hydrogen envelope of evolved massive stars,…
The Fermi Gamma-ray Observatory discovered about a thousand extragalactic sources emitting energy from 100 MeV to 100 GeV. The majority of these sources belong to the class of blazars characterized by a quasi-featureless optical spectrum…
We report on the first detailed infrared chemical analysis of five binary members (S277, S997, S975, S1031, and S1195) in the open cluster M67 (NGC 2682). These stars are located outside (bluer and/or brighter than) the main-sequence…
An extraordinarily massive cluster of red supergiants has been recently reported in the direction of the galactic coordinates $l = 25\rlap.^\circ3$; $b = -0\rlap.^\circ2$. This cluster is associated with an X-ray source, a very high-energy…
Red supergiants (RSGs) are an evolved He-burning phase in the lifetimes of moderately high mass (10 - 25 solar mass) stars. The physical properties of these stars mark them as an important and extreme stage of massive stellar evolution, but…
It is surprising to find dust around B type stars, as in the case of B[e] stars. These stars exhibit a dense, dusty environment witnessed by their infrared-excess and many emission lines from permitted and forbidden transitions. Given the…
As Be stars are restricted to luminosity classes III-V, but early B-type stars are believed to evolve into supergiants, it is to be expected that the Be phenomenon disappears at some point in the evolution of a moderately massive star,…
By using the high resolution spectrograph FLAMES@VLT we performed the first systematic campaign devoted to measure chemical abundances of blue straggler stars (BSSs). These stars, whose existence is not predicted by the canonical stellar…
The nature of possible evolutionary pathways between various types of dwarf galaxies is still not fully understood. Blue compact dwarf galaxies (BCDs) provide a unique window into dwarf galaxy formation and evolution and are often thought…
Luminous blue variables (LBVs) are rare objects of very high luminosity and mass loss rates, low wind velocities, exhibiting strong irregular photometric and spectral variability. They are generally believed to be a relatively short…
Blue metal-poor stars (BMPs) are main sequence stars that appear bluer and more luminous than normal turnoff stars. They were originally singled out by using B-V and U-B colour cuts. Early studies found that a larger fraction of field BMP…
We present a mini-survey of Galactic B[e] stars mainly undertaken with the Large Binocular Telescope (LBT). B[e] stars show morphological features with hydrogen emission lines and an infrared excess, attributed to warm circumstellar dust.…