Search Publications
The most obscured AGN in the COSMOS field
Berta, S.; Pozzi, F.; Vignali, C. +11 more
Highly obscured active galactic nuclei (AGN) are common in nearby galaxies, but are difficult to observe beyond the local Universe, where they are expected to significantly contribute to the black hole accretion rate density. Furthermore, Compton-thick (CT) absorbers (NH ≳ 1024 cm-2) suppress even the hard X-ray (2…
Anatomy of the AGN in NGC 5548. IV. The short-term variability of the outflows
Kaastra, J. S.; Kriss, G. A.; Bianchi, S. +16 more
During an extensive multiwavelength campaign that we performed in 2013-2014, we found the prototypical Seyfert 1 galaxy NGC 5548 in an unusual condition of heavy and persistent obscuration. The newly discovered "obscurer" absorbs most of the soft X-ray continuum along our line of sight and lowers the ionizing luminosity received by the classical w…
Molecular ions in the O-rich evolved star OH231.8+4.2: HCO+, H13CO+ and first detection of SO+, N2H+, and H3O+
Menten, K. M.; Sánchez Contreras, C.; Alcolea, J. +8 more
OH 231.8+4.2, a bipolar outflow around a Mira-type variable star, displays a unique molecular richness amongst circumstellar envelopes (CSEs) around O-rich AGB and post-AGB stars. We report line observations of the HCO+ and H13CO+ molecular ions and the first detection of SO+, N2H+,…
A radio map of the colliding winds in the very massive binary system HD 93129A
Nelan, E.; Marcote, B.; De Becker, M. +4 more
Context. Radio observations are an effective tool for discovering particle acceleration regions in colliding-wind binaries through detection of synchrotron radiation. Wind-collision region (WCR) models can reproduce the radio continuum spectra of massive binaries. However, key constraints for models come from high-resolution imaging. Only five WCR…
The structure of the Cepheus E protostellar outflow: The jet, the bowshock, and the cavity
Eislöffel, J.; Codella, C.; Benedettini, M. +7 more
Context. Protostellar outflows are a crucial ingredient of the star-formation process. However, the physical conditions in the warm outflowing gas are still poorly known.
Aims: We present a multi-transition, high spectral resolution CO study of the outflow of the intermediate-mass Class 0 protostar Cep E-mm. The goal is to determine the struc…
The photospheric solar oxygen project. III. Investigation of the centre-to-limb variation of the 630 nm [O I]-Ni I blend
Steffen, M.; Schmidt, W.; Ludwig, H. -G. +5 more
Context. The solar photospheric abundance of oxygen is still a matter of debate. For about ten years some determinations have favoured a low oxygen abundance which is at variance with the value inferred by helioseismology. Among the oxygen abundance indicators, the forbidden line at 630 nm has often been considered the most reliable even though it…
A steady-state supersonic downflow in the transition region above a sunspot umbra
Andretta, Vincenzo; Straus, Thomas; Fleck, Bernhard
We investigate a small-scale (~1.5 Mm along the slit), supersonic downflow of about 90 km s-1 in the transition region above the lightbridged sunspot umbra in AR 11836. The observations were obtained with the Interface Region Spectrograph (IRIS) on 2013 September 2 from 16:40 to 17:59 UT. The downflow shows up as redshifted "satellite" …
Stellar laboratories. IV. New Ga iv, Ga v, and Ga vi oscillator strengths and the gallium abundance in the hot white dwarfs G191-B2B and RE 0503-289
Rauch, T.; Werner, K.; Kruk, J. W. +1 more
Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, advanced non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These atmospheres are strongly dependent on the reliability of the atomic data that are used to calculate them.
Aims: Reliable Ga iv-vi oscillator stren…
Models of red giants in the CoRoT asteroseismology fields combining asteroseismic and spectroscopic constraints
Eggenberger, P.; Valentini, M.; Poretti, E. +17 more
Context. The availability of asteroseismic constraints for a large sample of red giant stars from the CoRoT and Kepler missions paves the way for various statistical studies of the seismic properties of stellar populations.
Aims: We use a detailed spectroscopic study of 19 CoRoT red giant stars to compare theoretical stellar evolution models …
The Herschel Virgo Cluster Survey. XVIII. Star-forming dwarf galaxies in a cluster environment
Boquien, M.; Bianchi, S.; Fritz, J. +22 more
To assess the effects of the cluster environment on the different components of the interstellar medium, we analyse the far-infrared (FIR) and submillimetre (submm) properties of a sample of star-forming dwarf galaxies detected by the Herschel Virgo Cluster Survey (HeViCS). We determine dust masses and dust temperatures by fitting a modified black…