Related papers: Mass-loss and Recent Spectral Changes in the Yello…

The circumstellar dust shells of intermediate initial-mass (about 1 to 8 solar masses) evolved stars are generated by copious mass loss during the asymptotic giant branch phase. The density structure of their circumstellar shell is the…

The fate of a massive star during the latest stages of its evolution is highly dependent on its mass-loss history and geometry, with the yellow hypergiants being key objects to study those phases of evolution. We present near-IR…

gamma Cassiopeiae (gCas) is a B0.5e star with peculiar X-ray emission properties and yet the prototype of its own small class. In this paper we examine the X-ray spectra for a 2004 XMM-Newton observation and a previously published 2001…

This contribution focuses on a rare example of the class of post-Red Supergiants, IRAS 17163-3907, the central star of the Fried Egg nebula. In particular, we discuss some of our recently published results in detail. The inner parts of the…

We present mid- and far- IR imaging of four famous hypergiant stars: the red supergiants $\mu$ Cep and VY CMa, and the warm hypergiants IRC +10420 and $\rho$ Cas. Our 11 to 37 $\mu$m SOFIA/FORCAST imaging probes cool dust not detected in…

We have performed our spectroscopic and multi-color photometric observations of the recurrent nova U Scorpii at the earliest stage of the 2010 outburst. 0.37 days after the discovery of the outburst, we can see broad and prominent emission…

We present results of our modeling the H-alpha line profile along the 2006 RS Oph outburst. At day 1.38 the very broad component of the H-alpha profile was possible to fit by a bipolar wind model. The model corresponds to a very fast…

We present results on spectroscopic observations of the fast-rotating active giant FK Comae, obtained mainly with the ESA-MUSICOS spectrograph at the Isaac Newton Telescope (INT) in 1996 and 1997 and also with the Aurelie spectrograph at…

New results of a Programme of study of BAL + IR + Fe II QSOs (at low and high redshift) are presented. Which are based mainly on deep Gemini GMOS integral field unit (IFU/3D) spectroscopy. We have performed a detailed study of the…

The evolutionary state of blue supergiants is still unknown. Stellar wind mass loss is one of the dominant processes determining the evolution of massive stars, and it may provide clues on the evolutionary properties of blue supergiants. As…

We present the 2.4-45 micrometer ISO-SWS spectrum of the Be star gamma Cas (B0.5 IVe). The spectrum is characterised by a thermal continuum which can be well fit by a power-law S_nu ~ nu^0.99 over the entire SWS wavelength range. For an…

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…

High-resolution spectroscopy was obtained of the FUors FU Ori and V1057 Cyg between 1995 and 2002 with SOFIN at NOT and with HIRES at Keck I. During those years FU Ori remained about 1 mag. (in B) below its 1938-39 maximum brightness, but…

We present near infrared spectroscopy of the recurrent nova RS Oph obtained on several occasions after its latest outburst in 2006 February. The 1-5 mircon spectra are dominated by the red giant, but the H I, He I, and coronal lines present…

Yellow hypergiants are rare and represent a fast evolutionary stage of massive evolved stars. That evolutionary phase is characterised by a very intense mass loss, the understanding of which is still very limited. Here we report ALMA…

We present a multi-wavelength (X-ray to optical) analysis, based on non-local thermodynamic equilibrium photospheric+wind models, of the B0 Ia-supergiant: $\epsilon$~Ori. The aim is to test the consistency of physical parameters, such as…

Red Supergiants (RSGs) are cool, evolved massive stars in their final evolutionary stage before exploding as a supernova. However, the evolution and fate of the most luminous RSGs remain uncertain. Observational evidence for luminous warm,…

B[e] supergiants and yellow hypergiants share a number of common properties regarding their circumstellar environments. Using the forbidden [O I] and [Ca II] lines as disk tracers, we suggest the presence of a Keplerian disk or ring around…

We present infrared interferometric imaging of the S-type Mira star Chi Cygni. The object was observed at four different epochs in 2005-2006 with the IOTA optical interferometer (H band). Images show up to 40% variation in the stellar…

We call attention to the fact that one of the brightest red supergiants in the SMC has recently changed its spectral type from K0-1 I (December 2004) to M4 I (December 2005) and back to K0-1 I (September 2006). An archival spectrum from the…