Search Publications
Basic physical parameters of a selected sample of evolved stars
Pasquini, L.; Weiss, A.; de Medeiros, J. R. +6 more
We present the detailed spectroscopic analysis of 72 evolved stars, which were previously studied for accurate radial velocity variations. Using one Hyades giant and another well studied star as the reference abundance, we determine the [Fe/H] for the whole sample. These metallicities, together with the T_eff values and the absolute V-band magnitu…
Revisiting the population of Galactic open clusters
Scholz, R. -D.; Piskunov, A. E.; Kharchenko, N. V. +2 more
We present results of a study of the galactic open cluster population based on the all-sky catalogue ASCC-2.5 (I/280A) compiled from Tycho-2, Hipparcos and other catalogues. The sample of optical clusters from ASCC-2.5 is complete up to about 850 pc from the Sun. The symmetry plane of the clusters' distribution is determined to be at Z_0=-22±4 pc,…
2MASS wide field extinction maps. I. The Pipe nebula
Alves, J.; Lombardi, M.; Lada, C. J.
Context: .
Aims: . We present a 8°×6°, high resolution extinction map of the Pipe nebula using 4.5 million stars from the Two Micron All Sky Survey (2MASS) point source catalog.
Methods: . The use of Nicer (Lombardi & Alves 2001, A&A, 377, 1023), a robust and optimal technique to map the dust column density, allows us to detect a…
Evolutionary state of magnetic chemically peculiar stars
Kochukhov, O.; Bagnulo, S.
Context: .The photospheres of about 5-10% of the upper main sequence stars exhibit remarkable chemical anomalies. Many of these chemically peculiar (CP) stars have a global magnetic field, the origin of which is still a matter of debate.
Aims: .We present a comprehensive statistical investigation of the evolution of magnetic CP stars, aimed at…
Effective temperature scale and bolometric corrections from 2MASS photometry
Ribas, I.; Jordi, C.; Masana, E.
We present a method to determine effective temperatures, angular semi-diameters and bolometric corrections for population I and II FGK type stars based on V and 2MASS IR photometry. Accurate calibration is accomplished by using a sample of solar analogues, whose average temperature is assumed to be equal to the solar effective temperature of 5777 …
Elemental abundances in the atmosphere of clump giants
Soubiran, C.; Korotin, S. A.; Bienaymé, O. +4 more
Aims.The aim of this paper is to provide the fundamental parameters and abundances for a large sample of local clump giants with a high accuracy. This study is a part of a big project, in which the vertical distribution of the stars in the Galactic disc and the chemical and dynamical evolution of the Galaxy are being investigated.
Methods: .Th…
Confirmation of the planet hypothesis for the long-period radial velocity variations of β Geminorum
Guenther, E. W.; Hatzes, A. P.; Cochran, W. D. +8 more
Aims.Our aim is to confirm the nature of the long period radial velocity measurements for β Gem first found by Hatzes & Cochran (1993).
Methods: .We present precise stellar radial velocity measurements for the K giant star β Gem spanning over 25 years. An examination of the Ca II K emission, spectral line shapes from high resolution data …
Newly discovered active binaries in the RasTyc sample of stellar X-ray sources. I. Orbital and physical parameters of six new binaries
Freire Ferrero, R.; Guillout, P.; Frasca, A. +3 more
We present the first results from follow-up optical observations, both photometric and spectroscopic, of stellar X-ray sources, selected from the RasTyc sample, resulting from the cross-correlation of ROSAT All-Sky Survey (RASS) and TYCHO catalogues. In particular, we report on the discovery of six late-type binaries, for which we obtained good ra…
Recovering the star formation rate in the solar neighborhood
Prada Moroni, P. G.; Degl'Innocenti, S.; Cignoni, M. +1 more
Aims.This paper develops a method for obtaining the star formation histories of a mixed, resolved population through the use of color-magnitude diagrams (CMDs). The method provides insight into the local star formation rate, analyzing the observations of the Hipparcos satellite through a comparison with synthetic CMDs computed for different histor…
uvby-β photometry of high-velocity and metal-poor stars. XI. Ages of halo and old disk stars
Moitinho, A.; Schuster, W. J.; Parrao, L. +2 more
New uvby-β data are provided for 442 high-velocity and metal-poor stars; 90 of these stars have been observed previously by us, and 352 are new. When combined with our previous two photometric catalogues, the data base is now made up of 1533 high-velocity and metal-poor stars, all with uvby-β photometry and complete kinematic data, such as proper …