Search Publications
Universal bolometric corrections for active galactic nuclei over seven luminosity decades
Maiolino, R.; Fiore, F.; Bianchi, S. +12 more
Context. The AGN bolometric correction is a key element for understanding black hole (BH) demographics and computing accurate BH accretion histories from AGN luminosities. However, current estimates still differ from each other by up to a factor of two to three, and rely on extrapolations at the lowest and highest luminosities.
Aims: Here we …
Temperature profiles of young disk-like structures. The case of IRAS 16293A
van Dishoeck, Ewine F.; Jørgensen, Jes K.; van 't Hoff, Merel L. R. +1 more
Context. Temperature is a crucial parameter in circumstellar disk evolution and planet formation because it governs the resistance of the gas to gravitational instability and sets the chemical composition of the planet-forming material.
Aims: We set out to determine the gas temperature of the young disk-like structure around the Class 0 proto…
Non-stoichiometric amorphous magnesium-iron silicates in circumstellar dust shells. Dust growth in outflows from supergiants
Tamanai, Akemi; Pucci, Annemarie; Dohmen, Ralf +1 more
Aims: We study the growth of dust in oxygen-rich stellar outflows in order to find out to which extent dust growth models can quantitatively reconcile with the quantities and nature of dust as derived from observations of the infrared emission from circumstellar dust shells.
Methods: We use a set of nine well-observed massive supergiants…
Li-rich K giants, dust excess, and binarity
Jorissen, A.; Pourbaix, D.; Escorza, A. +3 more
The origin of the Li-rich K giants is still highly debated. Here, we investigate the incidence of binarity among this family from a nine-year radial-velocity monitoring of a sample of 11 Li-rich K giants using the HERMES spectrograph attached to the 1.2 m Mercator Telescope. A sample of 13 non-Li-rich giants (8 of them being surrounded by dust acc…
How to disentangle geometry and mass-loss rate from AGB-star spectral energy distributions. The case of EP Aquarii
Jorissen, A.; Decin, L.; Groenewegen, M. A. T. +2 more
Context. High-angular-resolution observations of asymptotic giant branch (AGB) stars often reveal non-spherical morphologies for the gas and dust envelopes.
Aims: We aim to make a pilot study to quantify the impact of different geometries (spherically symmetric, spiral-shaped, and disc-shaped) of the dust component of AGB envelopes on spectra…
Mechanochemical synthesis of aromatic infrared band carriers. The top-down chemistry of interstellar carbonaceous dust grain analogues
Engrand, C.; Dartois, E.; Charon, E. +2 more
Context. Interstellar space hosts nanometre- to micron-sized dust grains, which are responsible for the reddening of stars in the visible. The carbonaceous-rich component of these grain populations emits in infrared bands that have been observed remotely for decades with telescopes and satellites. They are a key ingredient of Galactic radiative tr…
Validating post-AGB candidates in the LMC and SMC using SALT spectra
Szczerba, R.; Gezer, I.; Hrivnak, B. J. +8 more
We selected a sample of post-AGB candidates in the Magellanic Clouds on the basis of their near- and mid-infrared colour characteristics. Fifteen of the most optically bright post-AGB candidates were observed with the South African Large Telescope in order to determine their stellar parameters and thus to validate or discriminate their nature as p…
Extended view on the dust shells around two carbon stars
Groenewegen, M. A. T.; Kerschbaum, F.; Aringer, B. +4 more
Context. Stars on the asymptotic giant branch lose considerable amounts of matter through their dust-driven stellar winds. A number of such sources have been imaged by Herschel/PACS, revealing a diverse sample of different morphological types. Among them are a few examples which show geometrically thin, spherically symmetric shells which can be us…
Infrared interferometric imaging of the compact dust disk around the AGB star HR3126 with the bipolar Toby Jug Nebula
Weigelt, G.; Hofmann, K. -H.; Schertl, D. +1 more
Aims: The asymptotic giant branch (AGB) star HR3126, associated with the arcminute-scale bipolar Toby Jug Nebula, provides a rare opportunity to study the emergence of bipolar structures at the end of the AGB phase. Our goal is to image the central region of HR3126 with high spatial resolution.
Methods: We carried out long-baseline inter…