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The yellow hypergiant star V509 Cas is currently undergoing an extreme phase of evolution. Having experienced eruptive mass-loss outbursts in the 20th century, the star's effective temperature reached record high values in the early 2000s.…
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…
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…
The extreme NLS1 galaxy IRAS 13224-3809 shows significant variability, frequency depended time lags, and strong Fe K line and Fe L features in the long 2011 XMM-Newton observation. In this work we study the spectral properties of IRAS…
We present a new analysis of the physical conditions in three Herbig-Haro complexes (HH 54, HH 212, and the L 1157 protostellar jet) using archival data from the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. As described in…
We summarize the results of long-term spectral monitoring of yellow hypergiants (YHGs) of northern hemisphere with a R$\ge$60000 resolution. The spectra of these F-G stars of extremely high luminosity, compactly located at the top of the…
Aiming to perform a study of the warm dust and gas in the luminous blue variable star G79.29+0.46 and its associated nebula, we present infrared Spitzer imaging and spectroscopy, and new CO J=2-->1 and 4-->3 maps obtained with the IRAM 30m…
We analyze the differences in infrared circumstellar dust emission between oxygen rich Mira and non-Mira stars, and find that they are statistically significant. In particular, we find that these stars segregate in the K-[12] vs. [12]-[25]…
We describe and discuss remarkable infrared spectra, covering key portions of the $2-5$ $\mu$m wavelength interval, of the probable OH/IR supergiant 2MASS J17470898$-$2829561 (2M1747), located in direction of the Sgr B molecular cloud…
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…
We report on the discovery of a double nucleus in M 83, based on measurements of the line of sight velocity distribution of stars observed at near infrared wavelengths with the VLT ISAAC spectrograph. We observe two peaks separated by 2.7"…
We present the asteroseismic study of the early red-giant star KIC 4448777, complementing and integrating a previous work (Di Mauro et al. 2016), aimed at characterizing the dynamics of its interior by analyzing the overall set of data…
We present a study of McNeil's Nebula, a newly appeared reflection nebula in the L1630 cloud, together with photometry and spectroscopy of its source. New IR photometry compared to earlier 2MASS data shows that the star has brightened by…
The availability of precisely determined frequencies of radial and non-radial oscillation modes in red giants is finally paving the way for detailed studies of the internal structure of these stars. We look for the seismic signature of…
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…
Aims: Revealing the fragmentation, infall, and outflow processes in the immediate environment around massive young stellar objects is crucial for understanding the formation of the most massive stars. Methods: With this goal in mind we…
Warm debris disks are a sub-sample of the large population of debris disks, and display excess emission in the mid-IR. Around solar-type stars, very few objects show emission features in mid-IR spectroscopic observations, that are…
The high-resolution ($R\sim48\,000$) optical spectrum of the B-type supergiant LS 5112, identified as the optical counterpart of the post-AGB candidate IRAS 18379-1707, is analysed. We report the detailed identifications of the observed…
The dynamics of the surface and inner atmosphere of the red supergiant star Betelgeuse are the subject of numerous high angular resolution and spectroscopic studies. Here, we present three-telescope interferometric data obtained at 11.15…
At present there are many studies concerning jets towards low-mass young stellar objects, while equivalent studies towards massive or intermediate-mass young stellar objects are scarce. In a previous study, we found highly misaligned…