Search Publications
Analysing the SEDs of protoplanetary disks with machine learning
Pinte, C.; Woitke, P.; Kamp, I. +2 more
Context. The analysis of spectral energy distributions (SEDs) of protoplanetary disks to determine their physical properties is known to be highly degenerate. Hence, a full Bayesian analysis is required to obtain parameter uncertainties and degeneracies. The main challenge here is computational speed, as one proper full radiative transfer model re…
The intense production of silicates during the final AGB phases of intermediate mass stars
Dell'Agli, F.; Ventura, P.; Fabrizio, M. +7 more
Context. The formation of silicates in circumstellar envelopes of stars evolving through the asymptotic giant branch (AGB) is still highly debated given the uncertainties affecting stellar evolution modelling, the description of the dust formation process, and the capability of silicate grains to accelerate stellar outflows via radiation pressure.…
The hunt for formamide in interstellar ices. A toolkit of laboratory infrared spectra in astronomically relevant ice mixtures and comparisons to ISO, Spitzer, and JWST observations
van Dishoeck, E. F.; Rocha, W. R. M.; Slavicinska, K. +3 more
Context. Although solid-state pathways are expected to dominate the formation mechanisms of many complex organic molecules (COMs), very few COMs have been securely identified in interstellar ices, in stark contrast with the many COM detections in the gas phase. The launch of the James Webb Space Telescope (JWST) and its increase in sensitivity and…
The dusty circumstellar environment of Betelgeuse during the Great Dimming as seen by VLTI/MATISSE
Danchi, W.; Matter, A.; Lopez, B. +23 more
Context. The `Great Dimming' of the prototypical red supergiant Betelgeuse, which occurred between December 2019 and April 2020, gives us unprecedented insight into the processes occurring on the stellar surface and in the inner wind of this type of star. In particular it may bring further understanding of their dust nucleation and mass-loss proce…
OH mid-infrared emission as a diagnostic of H2O UV photodissociation. II. Application to interstellar photodissociation regions
Le Petit, F.; van Dishoeck, E. F.; Bron, E. +3 more
Context. Water photodissociation in the 114-143 nm UV range forms excited OH which emits at mid-infrared (MIR) wavelengths via highly excited rotational lines. These lines have only been detected with Spitzer in proto-planetary disks and shocks. Previous studies have shown that they are a unique diagnostic for water photodissociation. Thanks to it…
A study of carbon-rich post-AGB stars in the Milky Way to understand the production of carbonaceous dust from evolved stars
Dell'Agli, F.; Tailo, M.; Ventura, P. +5 more
Context. Knowledge of the Gaia, DR3 parallaxes of Galactic post-asymptotic giant branch (AGB) stars makes it possible to exploit these objects as tracers of AGB evolution, nucleosynthesis, and dust production as well as to use them to shed new light on still poorly known physical processes experienced by AGB stars.
Aims: The goal of this stud…
Study of oxygen-rich post-AGB stars in the Milky Way as a means to explain the production of silicates among evolved stars
Dell'Agli, F.; Ventura, P.; Marchetti, T. +4 more
Context. The study of post-asymptotic giant branch (post-AGB) stars is a valuable tool in improving our understanding of poorly known aspects of the evolution of the stars throughout the asymptotic giant branch (AGB). This can be done thanks to the availability of more accurate determinations of their surface chemical composition and the peculiar …
Atomic oxygen abundance toward Sagittarius B2
Wiesemeyer, Helmut; Güsten, Rolf; Seo, Youngmin +4 more
A substantial fraction of oxygen in diffuse clouds is unaccounted for by observations and is postulated to be in an unknown refractory form, referred to as unidentified depleted oxygen (UDO), which, depending on the local gas density, may contribute up to 50% of the total oxygen content. Previous Infrared Space Observatory (ISO) observations sugge…
Semi-analytic calculations for extended mid-infrared emission associated with FU Ori-type objects
Liu, Sheng-Yuan; Takami, Michihiro; Wang, Shiang-Yu +4 more
Aims: Near-infrared imaging polarimetry at high-angular resolutions has revealed an intriguing distribution of circumstellar dust toward FU Ori-type objects (FUors). These dust grains are probably associated with either an accretion disk or an infalling envelope. Follow-up observations in the mid-infrared would lead us to a better understandi…
Variations in the intermediate wind region of the blue supergiant 55 Cygni
Kraus, M.; Granada, A.; Arias, M. L. +6 more
Context. The quantitative near-infrared (NIR) spectroscopic synthesis is an important technique for determining wind properties of massive stars. The Brα line is an excellent mass-loss tracer and provides valuable information on the physical conditions of intermediate-wind regions. The knowledge of the wind properties gained by studying the NIR li…