Search Publications
The Hyades: distance, structure, dynamics, and age
Brown, A. G. A.; Crifo, F.; Gomez, A. +7 more
{We use absolute trigonometric parallaxes from the Hipparcos Catalogue to determine individual distances to members of the Hyades cluster, from which the 3-dimensional structure of the cluster can be derived. Inertially-referenced proper motions are used to rediscuss distance determinations based on convergent-point analyses. A combination of para…
Nearby stars of the Galactic disk and halo
Fuhrmann, Klaus
Model atmosphere analyses of echelle spectra of some fifty nearby F- and G-type stars are presented. The sample is confined to the main-sequence, turnoff and subgiant region, regardless of the metal abundance. On the base of these data, spectroscopic parallaxes are calculated and compared to the Hipparcos astrometry to explore the reliability of t…
HIPPARCOS photometry of Herbig Ae/Be stars
de Winter, D.; van den Ancker, M. E.; Tjin A Djie, H. R. E.
The photometric behaviour of a sample of 44 Herbig Ae/Be (HAeBe) candidate stars was studied using a uniform set of optical photometry obtained by the Hipparcos mission. Astrophysical parameters (distance, temperature, luminosity, mass, age) of this sample of stars were derived as well by combining the astrometric data provided by Hipparcos with d…
Interstellar reddening from the HIPPARCOS and TYCHO catalogues. I. Distances to nearby molecular clouds and star forming regions
Knude, J.; Hog, E.
The Hipparcos and Tycho Catalogues offer an interesting possibility to study the local distribution of interstellar reddening from the combination of data contained in the catalogues: Hipparcos parallaxes, Tycho B - V and spectral and luminosity classification compiled from the literature. Parallactic distances may be derived for known absorbing f…
Metal-rich globular clusters in the galactic disk: new age determinations and the relation to halo clusters
Salaris, M.; Weiss, A.
New age determinations of the galactic disk globular clusters 47 Tuc, M 71 and NGC 6352 have been performed with our up-to-date alpha -enhanced stellar models. We find that all three clusters are about 9.2 Gyr old and therefore coeval with the oldest disk white dwarfs. Several arguments are presented which indicate that the initial helium content …
The distribution of nearby stars in phase space mapped by Hipparcos. I. The potential well and local dynamical mass
Pichon, C.; Creze, M.; Chereul, E. +1 more
Hipparcos data provide the first, volume limited and absolute magnitude limited homogeneous tracer of stellar density and velocity distributions in the solar neighbourhood. The density of A-type stars more luminous than M_v=2. 5 can be accurately mapped within a sphere of 125 pc radius, while proper motions in galactic latitude provide the vertica…
The TYCHO Reference Catalogue
Makarov, V. V.; Lindegren, L.; Bastian, U. +5 more
The Tycho Reference Catalogue\ (TRC) contains high-quality positions and proper motions for 990 182\ stars of the Tycho Catalogue. The proper motions were derived from Tycho positions and Astrographic Catalogue\ positions reduced to the Hipparcos system. The median accuracy of the TRC position components is 40 mas at J1991.25. The median precision…
Mixing processes during the evolution of red giants with moderate metal deficiencies: the role of molecular-weight barriers
Wallerstein, George; Charbonnel, Corinne; Brown, Jeffery A.
We have assembled accurate abundance data for Li, C, and N as well as the (12}C/({13)) C ratio for five field giants with [Fe/H] =~ - 0.6 including Arcturus and two stars in the globular cluster 47 Tuc. Using their very precise Mbol values obtained from HIPPARCOS parallaxes, we can place them into an evolutionary sequence. The sequence …
The absolute magnitudes of RR Lyraes from HIPPARCOS parallaxes and proper motions
Garrido, R.; Evans, D. W.; Solano, E. +5 more
We have used HIPPARCOS proper motions and the method of Statistical Parallax to estimate the absolute magnitude of RR Lyrae stars. In addition we used the HIPPARCOS parallax of RR Lyrae itself to determine it's absolute magnitude. These two results are in excellent agreement with each other and give a zero-point for the RR Lyrae M_v,[Fe/H] relatio…
HIPPARCOS subdwarfs and globular cluster ages: the distance and age of M 92
Pont, F.; Turon, C.; Mayor, M. +1 more
A new determination of the distance and age of the old globular cluster M 92 (NGC 6341) is obtained from a consideration of a set of more than 500 subdwarf candidates with Hipparcos parallaxes. Precise [Fe/H] values are derived for most stars using the equivalent width of the Coravel cross-correlation function. We examine at some length the biases…