Related papers: Quantitative Spectroscopy of Supergiants
I briefly mention a few possible applications of very high spectral resolution spectroscopy with CRIRES to the study of nearby galaxies. This includes the fields of AGN, dynamically cold systems, super stellar and emission line clusters,…
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…
Luminous Blue Variables are massive evolved stars, here we introduce this outstanding class of objects. Described are the specific characteristics, the evolutionary state and what they are connected to other phases and types of massive…
OBSERVATIONS of galaxies to very faint magnitudes have revealed a population of blue galaxies at intermediate redshift$^{1-5}$. These galaxies represent a significant excess over the expectation of standard cosmological models for…
We used the DEIMOS spectrograph on the Keck II Telescope to obtain spectra of galaxies in the fields of five distant, rich galaxy clusters over the redshift range 0.5 < z < 0.9 in a search for luminous, compact, blue galaxies (LCBGs).…
The last ten years have opened up a new parameter space in time-domain astronomy with the discovery of transients defying our understanding of how stars explode. These extremes of the transient paradigm represent the brightest - called…
Main Sequence (MS) stars are by far the most numerous class in the Universe. They are often somewhat neglected as they are relatively quiet objects (but exceptions exist), though they bear testimony of the past and future of our Sun. An…
We present initial results from a wide-field, multi-colour imaging project, designed to study galaxy evolution in X-ray selected clusters at intermediate (z~0.25) and high redshifts (z~0.5). In this paper we give blue galaxy fractions from…
Supernova remnants serve as nearby laboratories relevant to many areas in Astrophysics, from stellar and galaxy evolution to extreme astrophysics and the formation of the heavy elements in the Universe. The Chandra X-ray mission has enabled…
The spectra of stars with the B[e] phenomenon are dominated by features that are related to physical conditions of circumstellar material around these objects and are not intrinsic to the stars. Because of this, they form a very…
We present HR Diagrams for the massive star populations in M31 and M33 including several different types of emission-line stars: the confirmed Luminous Blue Variables (LBVs), candidate LBVs, B[e] supergiants and the warm hypergiants. We…
We analyse emission-line properties of the bj-selected Stromlo-APM spectra (<z> = 0.05). Because this is a representative sample, we can study the global spectral properties of the local galaxy population. We classify spectra according to…
In this study, we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more…
Relativistic transients such as gamma-ray bursts (GRBs), jetted tidal disruption events, luminous fast blue optical transients, and fast X-ray transients, represent the brightest explosions in the Universe and serve dual roles as…
In this study we present an analysis of a sample of field blue straggler (BS) stars that show high ultra violet emission in their spectral energy distributions (SED): indication of a hot white dwarf (WD) companion to BS. Using photometry…
We combine Sloan Digital Sky Survey spectra of 22,000 luminous, red, bulge-dominated galaxies to get high S/N average spectra in the rest-frame optical and ultraviolet (2600A to 7000A). The average spectra of these massive, quiescent…
Thanks to incredible advances in instrumentation, surveys like the Sloan Digital Sky Survey have been able to find and catalog billions of objects, ranging from local M dwarfs to distant quasars. Machine learning algorithms have greatly…
This paper shows a technique for searching for bright massive stars in galaxies beyond the Local Group. To search for massive stars, we used the results of stellar photometry of the Hubble Space Telescope images using the DAOPHOT and…
Blazars dominate the extragalactic $\gamma$-ray sky and show pronounced flares. Using public Fermi-LAT light curves for 732 blazars with secure redshifts, I implement an automated pipeline to identify and characterize $\gamma$-ray bursts…
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…