Related papers: The Wind of Variable C in M33

We present progenitor-star detections, light curves, and optical spectra of SN2009ip and the 2009 optical transient in UGC2773 (U2773-OT), which were not genuine SNe. Precursor variability in the decade before outburst indicates that both…

In this poster we present the results of our analyses of three early massive stars in IC 1613, whose spectra have been observed with VIMOS and analyzed with CMFGEN and FASTWIND. One of the targets resulted a possible LBV and the other two…

We analyze STIS spectra in the 1150-1700 Angstrom wavelength range obtained for six early B supergiants in the neighboring galaxy M31. Because of their likely high (nearly solar) abundance, these stars were originally chosen to be directly…

(Shortened) Sequences of spectra of the nova-like cataclysmic variable (CV) BZ Cam were acquired on 9 nights in 2005-2006 in order to study the time development of episodes of wind activity known to occur frequently in this star. We confirm…

We present radiation-driven wind models for Luminous Blue Variables (LBVs) and predict their mass-loss rates. We study the effects of lower masses and modified abundances in comparison to the normal OB supergiants, and we find that the main…

Aims. The high energy spectrum of 3C 273 is usually understood in terms of inverse-Compton emission in a relativistic leptonic jet. This model predicts variability patterns and delays that could be tested with simultaneous observations from…

(Abridged) Stars more massive than $20-30M_{\odot}$ are so luminous that the radiation force on the cooler, more opaque outer layers can balance or exceed the force of gravity. These near or super-Eddington outer envelopes represent a long…

We present the first four years of BVRI photometry from an on-going survey to annually monitor the photometric behavior of evolved luminous stars in M31 and M33. Photometry was measured for 199 stars at multiple epochs, including 9 classic…

We present the first systematic spectropolarimetric study of Luminous Blue Variables (LBVs) in the Galaxy and the Magellanic Clouds, in order to investigate the geometries of their winds. We find that at least half of our sample show…

We present the first systematic spectropolarimetric study of Luminous Blue Variables (LBVs), and find that at least half those objects studied display evidence for intrinsic polarization -- a signature of significant inhomogeneity at the…

In this paper we review the observational data for OB stars in the SMC concentrating on those aspects of their spectra which provide information on processes which may strongly influence their evolution, namely mass-loss, rotational mixing…

If a massive star has lost significant mass during its red-supergiant stage, it would return to blue region in the HR diagram and spend a part of the core-He burning stage as a blue supergiant having a luminosity to mass ratio (L/M)…

We have fitted the Chandra Low Energy Transmission Grating spectrum of SS Cygni in outburst with a single temperature blackbody suffering the photoelectric opacity of a neutral column density and the scattering opacity of an outflowing…

We present photometric and spectroscopic observations of two luminous blue variable (LBV) stars in two extremely metal-deficient blue compact dwarf (BCD) galaxies, DDO 68 with 12+logO/H = 7.15 and PHL 293B with 12+logO/H = 7.72. These two…

The luminous blue variable (LBV) stars are peculiar very massive stars. The study of these stellar objects and their surroundings is important for understanding the evolution of massive stars and its effects on the interstellar medium. We…

A radial velocity (RV) survey to detect central stars in binary systems was carried out between 2002 and 2004. De Marco et al. (2004) reported that 10 out of 11 monitored stars exhibited strong RV variability, but periods were not detected.…

As a byproduct of our search for Galactic stellar systems with gamma-ray emission, we have identified an unrelated cool and evolved star (IRC-10412) that attracted our attention due to its strong radio emission level with a spectral index…

M31-RV was an extraordinarily luminous (~10^6 Lsun) eruptive variable, displaying very cool temperatures (roughly 1000 Kelvins) as it faded. The photometric behavior of M31-RV (and several other very red novae, i.e. luminous eruptive red…

OBA hypergiants (OBAHGs) are evolved massive stars with notable wind features in their optical spectrum. Located at the cool edge of the line-driven wind regime, many are candidate luminous blue variables (LBVs) likely near the Eddington…

For the first time, we obtained the high-resolution (R=15000 and 60000) optical spectra for the extremely luminous star No.12, associated with the IR-source IRAS20308+4104, a member of the CygOB2 association. We have found about 200…