Search Publications
The velocity ellipsoid in the Galactic disc using Gaia DR1
Majewski, Steven R.; Anguiano, Borja; Freeman, Kenneth C. +2 more
The stellar velocity ellipsoid of the solar neighbour (d < 200 pc) is re-examined using intermediate-old mono-abundance stellar groups with high-quality chemistry data together with parallaxes and proper motions from Gaia DR1. We find the average velocity dispersion values for the three space velocity components for the thin and thick discs of …
Verifying reddening and extinction for Gaia DR1 TGAS giants
Gontcharov, George A.; Mosenkov, Aleksandr V.
Gaia DR1 Tycho-Gaia Astrometric Solution parallaxes, Tycho-2 photometry, and reddening/extinction estimates from nine data sources for 38 074 giants within 415 pc from the Sun are used to compare their position in the Hertzsprung-Russell diagram with theoretical estimates, which are based on the PARSEC and MIST isochrones and the TRILEGAL model of…
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 …