Related papers: The rapidly evolving hypergiant IRC+10420: High-re…
Infrared emission from the dust shell around IRC+10216 is analysed in detail, employing a self-consistent model for radiatively driven winds around late-type stars that couples the equations of motion and radiative transfer in the dust. The…
We present two-dimensional (2D) radiative transfer modeling of IRC+10216 at selected moments of its evolution in 1995-2001, which correspond to three epochs of our series of 8 near-infrared speckle images (Osterbart et al. 2000, Weigelt et…
IRC +10420 is one of the extreme hypergiant stars that define the empirical upper luminosity boundary in the HR diagram. During their post--RSG evolution, these massive stars enter a temperature range (6000-9000 K) of increased dynamical…
We have used the sub-millimeter array to image the molecular envelope around IRC+10420. Our observations reveal a large and clumpy expanding envelope around the star. The molecular envelope shows a clear asymmetry in $^{12}$CO J=2--1…
WR 118 is a highly evolved Wolf-Rayet star of the WC10 subtype surrounded by a permanent dust shell absorbing and re-emitting in the infrared a considerable fraction of the stellar luminosity. We present the first diffraction-limited…
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…
(abridged) NML Cyg is a highly evolved OH/IR supergiant and supposed to be among the most luminous supergiants in the galaxy. We present the first diffraction limited 2.13micron observations of NML Cyg with 73mas resolution. The speckle…
IRC +10420 is one of the few known massive stars in rapid transition from the Red Supergiant phase to the Wolf-Rayet or Luminous Blue Variable phase. The star has an ionised wind and using the Br gamma hydrogen recombination emission we…
We present near-infrared speckle interferometry of the OH/IR star OH 104.9+2.4 in the K' band obtained with the 6m telescope of the Special Astrophysical Observatory (SAO). At a wavelength of lambda = 2.12 micron the diffraction-limited…
The evolved carbon-rich AGB star IRC +10216 (CW Leo) is the brightest mid-infrared source outside the solar system, as well as one of the closest examples of an evolved star losing mass. It has a complex and variable circumstellar structure…
We obtained near-infrared long-baseline interferometry of IRC+10420 with the AMBER instrument of ESO's Very Large Telescope Interferometer (VLTI) in low and high spectral resolution (HR) mode to probe the photosphere and the innermost…
We present new near-infrared (JHK) bispectrum speckle-interferometry monitoring of the carbon star IRC+10216 obtained between 1999 and 2001 with the SAO 6m telescope. The J-, H-, and K-band resolutions are 50mas, 56mas, and 73mas, resp. The…
We present the first speckle interferometric observations of R CrB, the prototype of a class of peculiar stars which undergo irregular declines in their visible light curves. The observations were carried out with the 6m telescope at the…
The results of a 7-epoch interferometric imaging study, at wavelengths in the near-infrared K-band, of the carbon star IRC +10216 are presented. The use of non- and partially-redundant aperture masking techniques on the 10-m Keck-I…
To understand the evolutionary stage of the peculiar supergiant IRC+10420, we have been taking spectra for several years at the 6m telescope. The optical spectrum of IRC+10420 of the years from 1992 through 1996 points to the increase in…
Among evolved massive stars likely in transition to the Wolf-Rayet phase, IRC +10420 is probably one of the most enigmatic. It belongs to the category of yellow hypergiants and it is characterized by quite high mass loss episodes. Even…
Our knowledge of the chemical properties of the circumstellar ejecta of the most massive evolved stars is particularly poor. We aim to study the chemical characteristics of the prototypical yellow hypergiant star, IRC +10420. For this…
We present medium resolution spectropolarimetry and long term photo-polarimetry of two massive post-red supergiants, IRC +10420 and HD 179821. The data provide new information on their circumstellar material as well as their evolution. In…
We present NAOMI/OASIS adaptive-optics assisted integral-field spectroscopy of the transitional massive hypergiant IRC +10420, an extreme mass-losing star apparently in the process of evolving from a Red Supergiant toward the Wolf-Rayet…
We investigate the dust growth in oxygen-rich stellar outflows for a set of nine well-observed massive supergiants with optically thin dust shells. Models of the infrared emission from their circumstellar dust shells are compared to their…