Search Publications
A synthetic view on structure and evolution of the Milky Way
Reylé, C.; Robin, A. C.; Derrière, S. +1 more
Since the Hipparcos mission and recent large scale surveys in the optical and the near-infrared, new constraints have been obtained on the structure and evolution history of the Milky Way. The population synthesis approach is a useful tool to interpret such data sets and to test scenarios of evolution of the Galaxy. We present here new constraints…
3D mapping of the dense interstellar gas around the Local Bubble
Crifo, F.; Lallement, R.; Welsh, B. Y. +2 more
We present intermediate results from a long-term program of mapping the neutral absorption characteristics of the local interstellar medium, motivated by the availability of accurate and consistent parallaxes from the Hipparcos satellite. Equivalent widths of the interstellar NaI D-line doublet at 5890 Å are presented for the lines-of-sight toward…
Distances and ages of NGC 6397, NGC 6752 and 47 Tuc
Grundahl, F.; Clementini, G.; Bragaglia, A. +4 more
New improved distances and absolute ages for the Galactic globular clusters NGC 6397, NGC 6752, and 47 Tuc are obtained using the Main Sequence Fitting Method. We derived accurate estimates of reddening and metal abundance for these three clusters using a strictly differential procedure, where the Johnson B-V and Strömgren b-y colours and UVES hig…
Abundances for metal-poor stars with accurate parallaxes. I. Basic data
Barbieri, M.; Claudi, R.; Carretta, E. +2 more
We present element-to-element abundance ratios measured from high dispersion spectra for 150 field subdwarfs and early subgiants with accurate Hipparcos parallaxes (errors <20%). For 50 stars new spectra were obtained with the UVES on Kueyen (VLT UT2), the McDonald 2.7 m telescope, and SARG at TNG. Additionally, literature equivalent widths wer…
Vertical distribution of Galactic disk stars. I. Kinematics and metallicity
Soubiran, C.; Siebert, A.; Bienaymé, O.
Nearly 400 Tycho-2 stars have been observed in a 720 square degree field in the direction of the North Galactic Pole with the high resolution echelle spectrograph ELODIE. Absolute magnitudes, effective temperatures, gravities and metallicities have been estimated, as well as distances and 3D velocities. Most of these stars are clump giants and spa…
Multiplicity among solar-type stars. III. Statistical properties of the F7-K binaries with periods up to 10 years
Arenou, F.; Udry, S.; Mayor, M. +1 more
Two CORAVEL radial velocity surveys - one among stars in the solar neighbourhood, the other in the Pleiades and in Praesepe - are merged to derive the statistical properties of main-sequence binaries with spectral types F7 to K and with periods up to 10 years. A sample of 89 spectroscopic orbits was finally obtained. Among them, 52 relate to a fre…
The low-level radial velocity variability in Barnard's star (= GJ 699). Secular acceleration, indications for convective redshift, and planet mass limits
Kürster, M.; Hatzes, A. P.; Cochran, W. D. +6 more
We report results from 2 1/2 yr of high precision radial velocity (RV) monitoring of Barnard's star. The high RV measurement precision of the VLT-UT2+UVES of 2.65 m s-1 made the following findings possible. (1) The first detection of the change in the RV of a star caused by its space motion (RV secular acceleration). (2) An anti-correla…
Reprocessing the Hipparcos data of evolved stars. III. Revised Hipparcos period-luminosity relationship for galactic long-period variable stars
Jorissen, A.; Pourbaix, D.; Platais, I. +1 more
We analyze the K band luminosities of a sample of galactic long-period variables using parallaxes measured by the Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from…
Kinetic equilibrium of iron in the atmospheres of cool stars. III. The ionization equilibrium of selected reference stars
Korn, A. J.; Gehren, T.; Shi, J.
Non-LTE line formation calculations of Fe I are performed for a small number of reference stars to investigate and quantify the efficiency of neutral hydrogen collisions. Using the atomic model that was described in previous publications, the final discrimination with respect to hydrogen collisions is based on the condition that the surface gravit…
Formation scenarios for the young stellar associations between galactic longitudes l = 280degr - 360degr
Dias, W. S.; Lépine, J. R. D.; Sartori, M. J.
We investigate the spatial distribution, the space velocities and age distribution of the pre-main sequence (PMS) stars belonging to Ophiuchus, Lupus and Chamaeleon star-forming regions (SFRs), and of the young early-type star members of the Scorpius-Centaurus OB association. These young stellar associations extend over the galactic longitude rang…