Related papers: Optical/near-infrared observations of the Fried Eg…
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 performed a mid-infrared imaging survey of evolved stars in order to study the dust distribution in circumstellar envelopes around these objects and to better understand the mass-loss mechanism responsible for the formation of these…
The fate of massive stars during the latest stages of their evolution is highly dependent on their mass-loss rate and geometry. These processes have a significant influence on stars with masses between 25 and 40 Msun, i.e., type II SN…
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…
Through CO mm-line and optical spectroscopy, we investigate the properties of the Fried Egg nebula IRAS 17163-3907, which has recently been proposed to be one of the rare members of the yellow hypergiant class. The CO J=2-1 and J=3-2…
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…
Massive evolved stars such as red supergiants and hypergiants are potential progenitors of Type II supernovae, and they are known for ejecting substantial amounts of matter, up to half their initial mass, during their final evolutionary…
Context. The mass-loss mechanism of cool massive evolved stars is poorly understood. The proximity of Betelgeuse makes it an appealing target to study its atmosphere, map the shape of its envelope, and follow the structure of its wind from…
Yellow hypergiants represent a short-lived evolutionary episode experienced by massive stars as they transit to and from a red supergiant phase. As such, their properties provide a critical test of stellar evolutionary theory. The galactic…
We initiated long-term optical interferometry monitoring of the diameters of unstable yellow hypergiants (YHG) with the goal of detecting both the long-term evolution of their radius and shorter term formation related to large mass-loss…
We present optical and near-infrared (NIR) spectroscopic observations of the nearby Type II supernova SN\,2024ggi from 250 and 581 days after the explosion. Comparing the evolution of the [\ion{O}{1}] at 6300, 6363 \text{\AA} doublet…
We present modeling research work of the winds and circumstellar environments of prototypical hot and cool massive stars using advanced radiative transfer (RT) calculations. This research aims at unraveling the detailed physics of various…
In the light of the recent results of the stellar interferometry, we examine the nature of the extra molecular layer outside the photosphere of red super- giant stars, so far studied mostly with the use of the infrared spectra. Although the…
Early-time observations of the Type II supernovae (SNe) 2013cu and 2013fs have revealed an interaction of ejecta with material near the star surface. Unlike the Type IIn SN2010jl, which interacts with a dense wind for ~1yr, the interaction…
Following the recent outburst of the recurrent nova RS Oph on 2006 Feb 12, we measured its near-infrared size using the IOTA, Keck, and PTI Interferometers at multiple epochs. The characteristic size of ~3 milliarcseconds hardly changed…
The yellow hypergiant Rho Cassiopeiae (F-G Ia0) has recently become very active with a tremendous outburst event in the fall of 2000. During the event the pulsating supergiant dimmed by more than a visual magnitude, while its effective…
We present new ISO-SWS data for a sample of 27 starburst galaxies, and with these data examine the issues of formation and evolution of the most massive stars in starburst galaxies. Using starburst models which incorporate time evolution,…
We report the first mid-IR detection of highly disturbed ionized gas in the ultraluminous infrared galaxy IRAS F00183-7111. The gas, traced by the 12.81um [NeII] and 15.56um [NeIII] lines, spans a velocity range of-3500 to 3000 km/s with…
Mass loss during the red supergiant (RSG) phase plays a crucial role in the evolution of an intermediate massive star, however, the underlying mechanism remains unknown. We aim to increase the sample of well-characterized RSGs at subsolar…
The increasing observed number of supernova events allows for finding ever more frequently the progenitor star in archive images. In a few cases, the progenitor star is a yellow supergiant star. The estimated position in the…