Search Publications
The supermassive black hole coincident with the luminous transient ASASSN-15lh
Kim, S.; Krühler, T.; Nicuesa Guelbenzu, A. +11 more
The progenitors of astronomical transients are linked to a specific stellar population and galactic environment, and observing their host galaxies hence constrains the physical nature of the transient itself. Here, we use imaging from the Hubble Space Telescope, and spatially resolved, medium-resolution spectroscopy from the Very Large Telescope o…
A new compact young moving group around V1062 Scorpii
Henning, Thomas; Goldman, Bertrand; Röser, Siegfried +3 more
Aims: We are searching for new open clusters or moving groups in the solar neighbourhood.
Methods: We used the Gaia-TGAS catalogue, cut it into narrow proper motion and parallax slices and searched for significant spatial over-densities of stars in each slice. We then examined stars forming over-densities in optical and near-infrared col…
Study of a sample of faint Be stars in the exofield of CoRoT. II. Pulsation and outburst events: Time series analysis of photometric variations
Eggenberger, P.; Frémat, Y.; Zorec, J. +5 more
Context. The class of Be stars are the epitome of rapid rotators in the main sequence. These stars are privileged candidates for studying the incidence of rotation on the stellar internal structure and on non-radial pulsations. Pulsations are considered possible mechanisms to trigger mass-ejection phenomena required to build up the circumstellar d…
The Gaia-ESO Survey: The N/O abundance ratio in the Milky Way
Gilmore, G.; Bayo, A.; Franciosini, E. +31 more
Context. The abundance ratio N/O is a useful tool to study the interplay of galactic processes, for example star formation efficiency, timescale of infall, and outflow loading factor.
Aims: We aim to trace log(N/O) versus [Fe/H] in the Milky Way and to compare this ratio with a set of chemical evolution models to understand the role of infall…
The Arches cluster revisited. II. A massive eclipsing spectroscopic binary in the Arches cluster
Crowther, P. A.; Evans, C. J.; Najarro, F. +3 more
We have carried out a spectroscopic variability survey of some of the most massive stars in the Arches cluster, using K-band observations obtained with SINFONI on the VLT. One target, F2, exhibits substantial changes in radial velocity (RV); in combination with new KMOS and archival SINFONI spectra, its primary component is found to undergo RV var…
The X-ray/UV ratio in active galactic nuclei: dispersion and variability
Paolillo, M.; Tombesi, F.; Vagnetti, F. +1 more
Context. The well established negative correlation between the αOX spectral slope and the optical/ultraviolet (UV) luminosity, a by-product of the relation between X-rays and optical/UV luminosity, is affected by relatively large dispersion. The main contributors to this dispersion can be variability in the X-ray/UV ratio and/or changes…
Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search
Stock, Stephan; Reffert, Sabine; Quirrenbach, Andreas
Context. The determination of accurate stellar parameters of giant stars is essential for our understanding of such stars in general and as exoplanet host stars in particular. Precise stellar masses are vital for determining the lower mass limit of potential substellar companions with the radial velocity method, but also for dynamical modeling of …
Local measurements of the mean interstellar polarization at high Galactic latitudes
Blinov, D.; Liodakis, I.; Panopoulou, G. V. +4 more
Very little information exists concerning the properties of the interstellar medium (ISM)-induced starlight polarization at high Galactic latitudes. Future optopolarimetric surveys promise to fill this gap. We conduct a small-scale pathfinding survey designed to identify the average polarization properties of the diffuse ISM locally, at regions wi…
Solar meridional circulation from twenty-one years of SOHO/MDI and SDO/HMI observations. Helioseismic travel times and forward modeling in the ray approximation
Gizon, Laurent; Liang, Zhi-Chao; Birch, Aaron C. +2 more
Context. The solar meridional flow is an essential ingredient in flux-transport dynamo models. However, no consensus on its subsurface structure has been reached.
Aims: We merge the data sets from SOHO/MDI and SDO/HMI with the aim of achieving a greater precision on helioseismic measurements of the subsurface meridional flow.
Methods: Th…
SPOTS: The Search for Planets Orbiting Two Stars. III. Complete sample and statistical analysis
Kuzuhara, M.; Marzari, F.; Henning, Th. +8 more
Binary stars constitute a large percentage of the stellar population, yet relatively little is known about the planetary systems orbiting them. Most constraints on circumbinary planets (CBPs) so far come from transit observations with the Kepler telescope, which is sensitive to close-in exoplanets but does not constrain planets on wider orbits. Ho…