Search Publications
A NLTE line formation for neutral and singly ionized calcium in model atmospheres of B-F stars
Sitnova, T. M.; Mashonkina, L. I.; Ryabchikova, T. A.
We present non-local thermodynamic equilibrium (NLTE) line formation calculations for Ca I and Ca II in B-F stars. The sign and the magnitude of NLTE abundance corrections depend on line and stellar parameters. We determine calcium abundances for nine stars with reliable stellar parameters. For all stars, where the lines of both species could be m…
The phase function and density of the dust observed at comet 67P/Churyumov-Gerasimenko
Lasue, J.; Jorda, L.; Lamy, P. L. +44 more
The OSIRIS camera onboard Rosetta measured the phase function of both the coma dust and the nucleus. The two functions have a very different slope versus the phase angle. Here, we show that the nucleus phase function should be adopted to convert the brightness to the size of dust particles larger than 2.5 mm only. This makes the dust bursts observ…
On the observational diagnostics to separate classical and disk-like bulges
Costantin, Luca; Morelli, L.; Dalla Bontà, E. +3 more
Flattened bulges with disk-like properties are considered to be the end product of secular evolution processes at work in the inner regions of galaxies. On the contrary, classical bulges are characterized by rounder shapes and thought to be similar to low-luminosity elliptical galaxies. We aim at testing the variety of observational diagnostics wh…
The blue straggler V106 in NGC 6791: a prototype progenitor of old single giants masquerading as young
Ryde, N.; Grundahl, F.; Stello, D. +18 more
We determine the properties of the binary star V106 in the old open cluster NGC 6791 . We identify the system to be a blue straggler cluster member by using a combination of ground-based and Kepler photometry and multi-epoch spectroscopy. The properties of the primary component are found to be M_p∼ 1.67 M_{⊙ }, more massive than the cluster turn-o…
Revisiting Stephan's Quintet with deep optical images
Cuillandre, Jean-Charles; Duc, Pierre-Alain; Renaud, Florent
Stephan's Quintet, a compact group of galaxies, is often used as a laboratory to study a number of phenomena, including physical processes in the interstellar medium, star formation, galaxy evolution, and the formation of fossil groups. As such, it has been subject to intensive multiwavelength observation campaigns. Yet, models lack constrains to …
Absorption and emission features of 7Be II in the outburst spectra of V838 Her (Nova Her 1991)
Molaro, P.; Izzo, L.; Selvelli, P.
High- and low-resolution International Ultraviolet Explorer (IUE) spectra of V838 Her in the early outburst stages exhibit a strong absorption feature shortward of λ3130. We discuss the nature of this spectral feature and provide convincing evidence that it corresponds to the blueshifted resonance doublet of singly ionized 7Be recently …
K2-232 b: a transiting warm Saturn on an eccentric P = 11.2 d orbit around a V = 9.9 star
Jones, M. I.; Rabus, M.; Espinoza, N. +12 more
We report the discovery of K2-232 b using photometric data of the Kepler K2 satellite coupled with ground-based spectroscopic observations. K2-232 b has a mass of MP = 0.397 ± 0.037 MJ, a radius of RP = 1.00 ± 0.020 RJ, and a moderately low equilibrium temperature of Teq = 1030 ± 15 K due to i…
A multiwavelength study of SXP 1062, the long-period X-ray pulsar associated with a supernova remnant
Haberl, F.; Gallagher, J.; Guerrero, M. A. +5 more
SXP 1062 is a Be X-ray binary (BeXB) located in the Small Magellanic Cloud. It hosts a long-period X-ray pulsar and is likely associated with the supernova remnant MCSNR J0127-7332. In this work we present a multiwavelength view on SXP 1062 in different luminosity regimes. We consider monitoring campaigns in optical (OGLE survey) and X-ray (Swift …
Galaxy pre-processing in substructures around z ∼ 0.4 galaxy clusters
Demarco, R.; Balestra, I.; Rosati, P. +5 more
We present a detailed analysis of galaxy colours in two galaxy clusters at z ∼ 0.4, MACS J0416.1 - 2403 and MACS J1206.2 - 0847, drawn from the CLASH-VLT survey, to investigate the role of pre-processing in the quenching of star formation. We estimate the fractions of red and blue galaxies within the main cluster and the detected substructures and…
Globular clusters in high-redshift dwarf galaxies: a case study from the Local Group
Weisz, Daniel R.; Zick, Tom O.; Boylan-Kolchin, Michael
We present the reconstructed evolution of rest-frame ultraviolet (UV) luminosities of the most massive Milky Way dwarf spheroidal satellite galaxy, Fornax, and its five globular clusters (GCs) across redshift, based on analysis of the stellar fossil record and stellar population synthesis modelling. We find that (1) Fornax's (proto-)GCs can genera…