Related papers: The Wind of Variable C in M33
High resolution optical spectra (R = 60 000) of the LBV star P Cyg beyond outburst were obtained on the 6-meter BTA telescope in the wavelength range 477-780 nm. We perform a detailed identification of different types lines (photospheric…
We present quantitative studies of 8 late O and early B-type supergiants in the Magellanic Clouds using far-ultraviolet FUSE, ultraviolet IUE/HST and optical VLT-UVES spectroscopy. Temperatures, mass-loss rates and CNO abundances are…
BL Lacertae (BL Lac) is categorized as TeV blazar and considered as a possible source of astrophysical neutrinos. In 2020, the brightest X-ray flare ever detected from it. A detailed study can answer many puzzling questions related to…
Observations of interstellar scintillations at radio wavelengths reveal a Kolmogorov-like scaling of the electron density spectrum with a spectral slope of -5/3 over six decades in wavenumber space. A similar turbulent density spectrum in…
WD J005311 is the peculiar stellar remnant of the Galactic supernova from 1181, and appears to have been the merger of two white dwarfs. We present time-resolved spectroscopy of WD J005311 showing emission line variability on a wide range…
We present velocity spectra measured in three cryogenic liquid 4He steady flows: grid and wake flows in a pressurized wind tunnel capable of achieving mean velocities up to 5 m/s at temperatures above and below the superfluid transition,…
Towards the end of their evolution hot massive stars develop strong stellar winds and appear as emission line stars, such as WR stars or LBVs. The quantitative description of the mass loss in these important pre-SN phases is hampered by…
[Abridged] We have studied the optical spectra of 28 O- and early B-type stars in the Large Magellanic Cloud, 22 of which are associated with the young star-forming region N11. Stellar parameters are determined using an automated fitting…
We present the results of an extensive analysis of the optical, ultraviolet, X-ray and $\gamma$-ray data collected from the observations of the BL Lac objects prototype BL Lacertae carried out over a period of nearly 13 years, between…
Condensate clouds strongly impact the spectra of brown dwarfs and exoplanets. Recent discoveries of variable L/T transition dwarfs argued for patchy clouds in at least some ultracool atmospheres. This study aims to measure the frequency and…
Different types of hot subdwarfs may have different origins, which will cause them to present different radial velocity (RV) variability properties. Only 6$\pm$4% of our single-lined He-rich hot subdwarfs that only show spectroscopic…
Recent work suggests that many luminous blue variables (LBVs) and B[e] supergiants (sgB[e]) are isolated, implying that they may be products of massive binaries, kicked by partner supernovae (SNe). However, the evidence is somewhat complex…
Mass loss from massive stars located in the part of the Hertzsprung-Russell diagram (HRD) where we find luminous blue variables (LBVs) is profoundly important for stellar evolution yet poorly understood. We use time-dependent…
We present photoelectric and spectral observations of a hot candidate proto-planetary nebula - early B-type supergiant with emission lines in spectrum - IRAS 19336-0400. The light and color curves display fast irregular brightness…
We report the results of optical spectroscopy of the candidate evolved massive star MN44 revealed via detection of a circular shell with the Spitzer Space Telescope. First spectra taken in 2009 May--June showed the Balmer lines in emission…
M dwarf stars are currently the main targets in searches for potentially habitable planets. However, their winds have been suggested to be harmful to planetary atmospheres. Here, in order to better understand the winds of M dwarfs and also…
We discuss properties of oscillatory convective modes in low-mass red giants, and compare them with observed properties of the long secondary periods (LSPs) of semi-regular red giant variables. Oscillatory convective modes are very…
Luminous Blue Variables (LBVs) are massive stars that are likely to be a transitionary phase between O stars and hydrogen-free classical Wolf-Rayet stars. The variability of these stars has been an area of study for both professional and…
Widespread galactic winds emanate from the Large Magellanic Cloud (LMC), with the 30 Doradus starburst region generating the fastest and most concentrated gas flows. We report on the gas distribution, kinematics, and ionization conditions…
In this Letter, we report the results of spectroscopic and photometric monitoring of the candidate luminous blue variable (LBV) WS1, which was discovered in 2011 through the detection of a mid-infrared circular shell and follow-up optical…