Search Publications
The Tycho-2 catalogue of the 2.5 million brightest stars
Makarov, V. V.; Bastian, U.; Fabricius, C. +6 more
The Tycho-2 Catalogue presented here is an astrometric reference catalogue containing positions and proper motions as well as two-colour photometric data for the 2.5 million brightest stars in the sky. The Tycho-2 positions and magnitudes are based on precisely the same observations as the original Tycho Catalogue (hereafter Tycho-1) collected by …
The Effect of the Outer Lindblad Resonance of the Galactic Bar on the Local Stellar Velocity Distribution
Dehnen, Walter
Hydrodynamic modeling of the inner Galaxy suggests that the radius of the outer Lindblad resonance (OLR) of the Galactic bar lies in the vicinity of the Sun. How does this resonance affect the distribution function in the outer parts of a barred disk, and can we identify any effect of the resonance in the velocity distribution actually observed in…
Abundances and Kinematics of Field Halo and Disk Stars. I. Observational Data and Abundance Analysis
Fulbright, Jon P.
We describe observations and abundance analysis of a high-resolution, high signal-to-noise ratio survey of 168 stars, most of which are metal-poor dwarfs. We follow a self-consistent LTE analysis technique to determine the stellar parameters and abundances, and we estimate the effects of random and systematic uncertainties on the resulting abundan…
Distances, Ages, and Epoch of Formation of Globular Clusters
Fusi Pecci, Flavio; Carretta, Eugenio; Clementini, Gisella +1 more
We review the results on distances and absolute ages of Galactic globular clusters (GCs) obtained after the release of the Hipparcos catalog. Several methods aimed at the definition of the Population II local distance scale are discussed, and their results compared, exploiting new results for RR Lyraes in the Large Magellanic Cloud (LMC). We find …
Revision of the initial-to-final mass relation
Weidemann, V.
The initial-to final mass relation is revised in view of new theoretical and observational data. Recent stellar evolution models predict core masses at the beginning of the thermally pulsing asymptotic giant branch which practically coincide with final white dwarf masses derived for NGC 3532 and the binary white dwarf PG 0922+162. The Hyades white…
A catalogue of symbiotic stars
Ivison, R. J.; Munari, U.; Friedjung, M. +2 more
We present a new catalogue of symbiotic stars. In our list we include 188 symbiotic stars as well as 30 objects suspected of being symbiotic. For each star, we present basic observational material: coordinates, V and K magnitudes, ultraviolet (UV), infrared (IR), X-ray and radio observations. We also list the spectral type of the cool component, t…
The local density of matter mapped by Hipparcos
Flynn, Chris; Holmberg, Johan
We determine the velocity distribution and space density of a volume-complete sample of A and F stars, using parallaxes and proper motions from the Hipparcos satellite. We use these data to solve for the gravitational potential vertically in the local Galactic disc, by comparing the Hipparcos measured space density with predictions from various di…
Models for Old, Metal-poor Stars with Enhanced α-Element Abundances. I. Evolutionary Tracks and ZAHB Loci; Observational Constraints
VandenBerg, Don A.; Alexander, David R.; Swenson, Fritz J. +2 more
Stellar evolutionary tracks have been computed for 17 [Fe/H] values from -2.31 to -0.30 assuming, in each case, [α/Fe]=0.0, 0.3, and 0.6. The helium abundance was assumed to vary from Y=0.2352 at [Fe/H]=-2.31 to Y=0.2550 at [Fe/H]=-0.30 and held constant for the different choices of [α/Fe] at a fixed iron content. Masses in the range 0.5<=M
Chemical composition of 90 F and G disk dwarfs
Zhao, G.; Nissen, P. E.; Chen, Y. Q. +2 more
High resolution, high S/N spectra have been obtained for a sample of 90 F and G main-sequence disk stars covering the metallicity range -1.0 < [Fe/H] < +0.1, and have been analysed in a parallel way to the work of Edvardsson et al. (\cite{Edvardsson93a}) in order to re-inspect their results and to reveal new information on the chemical evolu…
The Nature of the lithium rich giants. Mixing episodes on the RGB and early-AGB
Charbonnel, C.; Balachandran, S. C.
We present a critical analysis of the nature of the so-called Li-rich RGB stars. For a majority of the stars, we have used Hipparcos parallaxes to determine masses and evolutionary states by comparing their position on the Hertzsprung-Russell diagram with theoretical evolutionary tracks. Among the twenty Li-rich giants whose location on the HR dia…