Search Publications
Evolutionary models for solar metallicity low-mass stars: mass-magnitude relationships and color-magnitude diagrams
Hauschildt, P. H.; Allard, F.; Baraffe, I. +1 more
We present evolutionary models for low mass stars from 0.075 to 1 M_sun for solar-type metallicities [M/H]= 0 and -0.5. The calculations include the most recent interior physics and the latest generation of non-grey atmosphere models. We provide mass-age-color-magnitude relationships for both metallicities. The mass-M_V and mass-M_K relations are …
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…
Steps toward interstellar silicate mineralogy. IV. The crystalline revolution
Waters, L. B. F. M.; Mutschke, H.; Henning, Th. +3 more
Mid- and far-infrared spectra gained by the Short Wavelength Spectrometer (SWS) of the Infrared Space Observatory (ISO) satellite have provided striking evidence for the presence of crystalline silicates in comets, circumstellar envelopes around young stars and, most of all, evolved stars and planetary nebulae. Since optical properties of astrophy…
The spectrum of the young star HD 100546 observed with the Infrared Space Observatory
Waters, L. B. F. M.; Vandenbussche, B.; Waelkens, C. +3 more
It is generally assumed that planets form in the dusty disks that surround young stars (Beckwith & Sargent 1996). The Infrared Space Observatory (Kessler et al. 1996) now enables us to determine the characteristics of these disks with unprecedented spectral resolution and signal-to-noise. We present here ISO spectra of the disk that surrounds …
HST study of Lyman-alpha emission in star-forming galaxies: the effect of neutral gas flows
Mas-Hesse, J. M.; Terlevich, E.; Terlevich, R. +3 more
We present high dispersion HST GHRS UV spectroscopic observations of 8 H II galaxies covering a wide range of metallicities and physical properties. We have found Lyalpha \ emission in 4 galaxies with blueshifted absorption features, leading to P Cygni like profiles in 3 of them. In all these objects the O I and Si II absorption lines are also blu…
An ultraviolet, optical and infrared study of Herbig Ae/Be stars
Waelkens, C.; Malfait, K.; Bogaert, E.
We have selected a list of 45 Herbig Ae/Be-type candidates on the base of their IRAS colors and their spectral types. We propose the presence of a broad infrared excess as a defining criterion for these stars, rather than the detection of circumstellar nebulosity. In this way, our selection also includes more evolved young stars, that are no longe…
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…
The dark side of star formation in the Antennae galaxies
Cesarsky, C.; Duc, P. -A.; Madden, S. C. +6 more
We compare mid-infrared images of the Antennae galaxies (NGC4038/39) from the Infrared Space Observatory, with optical images from the Hubble Space Telescope. The mid-infrared observations show that the most intense starburst in this colliding system of galaxies takes place in an off-nucleus region that is inconspicuous at optical wavelengths. The…