Search Publications

The Kinematics and Origin of smr Stars

Grenon, M.

Ages and kinematics are revised for SMR stars ([M/H] >+0.30) common to NLTT and HIPPARCOS catalogues. The origin of MR to SMR stars appears heterogeneous: part of them, of intermediate age, were formed few kpc inside the solar orbit, from slowly enriched gas, whereas the oldest SMRs were born early, closer to the galactic center where the metal…

Kinematics of nearby Subdwarfs

Wielen, R.; Jahreiss, H.; Fuchs, B.

A sample of subdwarfs with accurate space velocities and standarized metallicities is presented. This was constructed by combining Hipparcos parallaxes and proper motions with radial velocities and metallicities from Carney et al. (1994; CLLA). The accurate Hipparcos parallaxes lead to an – upward – correction factor of 11% of the photometric dist…

Old, Low-Mass, Metal-Rich (SMR) Stars

Soubiran, C.; Lebreton, Y.; Cayrel de Strobel, G. +1 more

The authors of this paper try to disentangle the many problems arisen from a new enlarged sample of nearby low-mass,metal-rich-stars. These stars have reliable absolute magnitudes, deduced from Hipparcos parallaxes, precise bolometric corrections, effective temperatures and metal abundances from high resolution detailed spectroscopic analyses. The…

Faint Stars and the Structure of the Galaxy

Wolf, C.; Meisenheimer, K.; Jahreiss, H. +2 more

Sequences of Nearby Open Clusters with Hipparcos

Arenou, F.; Lebreton, Y.; Robichon, N.

An Estimation of the Galactic Escape Velocity From High-Velocity Metal-Poor Stars

Meillon, L.

A large number of high-velocity stars was included in the Hipparcos Input Catalogue for the purpose of determining the galactic escape velocity in the solar vicinity. However, the `fastest' stars known, listed by Carney et al. (1994, CLLA) were not included because they are too faint. In the intersection between the CLLA list and the Hipparcos Cat…

Metallicities of Nearby K-Dwarfs

Flynn, Chris; Kotoneva, Eira

The so-called ``G-dwarf problem'' emerged in the 1960's when it was noticed that the observed metal distribution of nearby stars differs from what is expected in simple models of the evolution of the Galaxy. We have determined metallicities for a sample of over 100 K dwarfs drawn from the Hipparcos catalog, using R-I colours to estimate effective …

Study of Early-Type Stars Populations and of Their Origin

Royer, F.

Eight Gyr Minimum Disk Age from Hipparcos

Jimenez, Raul; Flynn, Chris; Kotoneva, Eira