Search Publications
Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models
Przybilla, N.; Nieva, M. -F.
Context. Early B-type stars are ideal indicators for present-day cosmic abundances since they preserve their pristine abundances and typically do not migrate far beyond their birth environments over their short lifetimes, in contrast to older stars like the Sun. They are also unaffected by depletion onto dust grains, unlike the cold/warm interstel…
Rotational velocities of A-type stars. IV. Evolution of rotational velocities
Royer, F.; Zorec, J.
Context. In previous works of this series, we have shown that late B- and early A-type stars have genuine bimodal distributions of rotational velocities and that late A-type stars lack slow rotators. The distributions of the surface angular velocity ratio Ω/Ωcrit (Ωcrit is the critical angular velocity) have peculiar shapes a…
Analysis of astrometric catalogues with vector spherical harmonics
Mignard, F.; Klioner, S.
Aims: We compare stellar catalogues with position and proper motion components using a decomposition on a set of orthogonal vector spherical harmonics. We aim to show the theoretical and practical advantages of this technique as a result of invariance properties and the independence of the decomposition from a prior model.
Methods: We de…
Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project
de Bruijne, J. H. J.; Eilers, A. -C.
Context. The Hundred-Thousand-Proper-Motion (HTPM) project will determine the proper motions of ~113 500 stars using a ~23-year baseline. The proper motions will be based on space-based measurements exclusively, with the Hipparcos data, with epoch 1991.25, as first epoch and with the first intermediate-release Gaia astrometry, with epoch ~2014.5, …
The SOPHIE search for northern extrasolar planets. IV. Massive companions in the planet-brown dwarf boundary
Bouchy, F.; Moutou, C.; Queloz, D. +20 more
Context. The mass domain where massive extrasolar planets and brown dwarfs lie is still poorly understood. Indeed, not even a clear dividing line between massive planets and brown dwarfs has been established yet. This is partly because these objects are very scarce in close orbits around solar-type stars, the so-called brown dwarf desert. Owing to…
The Penn State-Toruń Centre for Astronomy Planet Search stars. I. Spectroscopic analysis of 348 red giants
Nowak, G.; Zieliński, P.; Adamów, M. +2 more
Aims: We present basic atmospheric parameters (Teff, log g, vt, and [Fe/H]) as well as luminosities, masses, radii, and absolute radial velocities for 348 stars, presumably giants, from the ~1000 star sample observed within the Penn State-Toruń Centre for Astronomy Planet Search with the High Resolution Spectrograph of t…
Infrared excess around nearby red giant branch stars and Reimers law
Groenewegen, M. A. T.
Context. Mass loss is one of the fundamental properties of asymptotic giant branch (AGB) stars, but for stars with initial masses below ~1 M⊙, the mass loss on the first red giant branch (RGB) actually dominates mass loss on the AGB. Nevertheless, mass loss on the RGB is still often parameterised by a simple Reimers law in stellar evolu…
Solar-like oscillations in the G9.5 subgiant β Aquilae
Grundahl, F.; Kjeldsen, H.; Leccia, S. +3 more
Context. An interesting asteroseismic target is the G9.5 IV solar-like star β Aql. This is an ideal target for asteroseismic investigations, because precise astrometric measurements are available from Hipparcos that greatly help in constraining the theoretical interpretation of the results. The star was observed during six nights in August 2009 by…
Distance to northern high-latitude HI shells
Lallement, R.; Puspitarini, L.
Context. A detailed three-dimensional (3D) distribution of interstellar matter in the solar neighborhood is increasingly necessary. It would allow a more realistic computation of photons and cosmic rays propagation, which is of prime importance for microwave and gamma-ray background emission interpretation, as well as a better understanding of the…
The hypergiant HR 8752 evolving through the yellow evolutionary void
Meynet, G.; Lobel, A.; Kolka, I. +5 more
Context. We study the time history of the yellow hypergiant HR 8752 based on high-resolution spectra (1973-2005), the observed MK spectral classification data, B - V- and V-observations (1918-1996) and yet earlier V-observations (1840-1918).
Aims: Our local thermal equilibrium analysis of the spectra yields accurate values of the effective te…