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 …
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…
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…
A HST spectroscopic study of QSOs with intermediate redshift damped Lyalpha systems
Deharveng, Jean-Michel; Bergeron, Jacqueline; Le Brun, Vincent +1 more
We present HST spectra for a sample of six QSOs with intermediate redshift (z_ale 1.) damped Lyalpha systems. These observations aim at measuring the Hi column density and detect metal lines in order to investigate the metal enrichment of the gas, as well as the presence of neutral species, molecules and dust. All systems selected on the basis of …
Spectral analyses of PG 1159 star: constraints on the GW Virginis pulsations from HST observations
Dreizler, S.; Heber, U.
We present the results of a quantitative analysis of UV and optical spectra of nine PG 0122+200ls, very hot hydrogen-deficient [pre-] white dwarfs, by means of line blanketed NLTE model atmospheres. Four programme stars constitute the GW Vir variables, a class of non-radial g-mode pulsators. Precise effective temperatures, carbon, nitrogen and oxy…
On the age of the nearby blue compact dwarf galaxy SBS 0335-052
Thuan, T. X.; Izotov, Y. I.; Papaderos, P. +2 more
UBVRI surface photometry and long-slit spectrophotometric observations are used to investigate the evolutionary status and put constraints on the age of the underlying stellar population of the eastern component of a nearby pair of dwarf galaxies, the blue compact dwarf galaxy SBS\ 0335-052E. We show that ionized gas emission extending out to dist…
The nucleus and inner coma of Comet 46P/Wirtanen
Jorda, L.; Lamy, P. L.; Toth, I. +2 more
We report the detection of the nucleus of comet 46P/Wirtanen from analysis of images taken with the Planetary Camera (WFPC2) of the Hubble Space Telescope (HST) on 28 August 1996. The high spatial resolution (a WFPC2 pixel projects to 50 km at the distance of the comet) allowed us to separate the signal of the nucleus from that of the coma and to …
Hubble Space Telescope observations of the nucleus and inner coma of comet 19P/1904 Y2 (Borrelly)
Weaver, Harold A.; Toth, Imre; Lamy, Philippe L.
The nucleus of comet 19P/Borrelly was detected using the Planetary Camera (WFPC2) of the Hubble Space Telescope (HST). During the time of our observations, the comet was 0.62 AU from the Earth, 1.40 AU from the Sun, and had a solar phase angle of 38°. The high spatial resolution of the HST images allowed us to discriminate clearly between the sign…
The beta Pictoris circumstellar disk. XXIV. Clues to the origin of the stable gas
Deleuil, M.; Spyromilio, J.; Feldman, P. D. +11 more
GHRS high resolution spectra of {beta \:Pictoris} were obtained to study the stable gas around this star. Several elements are detected and their abundances measured. Upper limits to the abundances of others are also measured. The data permit improved chemical analysis of the stable gas around {beta \:Pictoris}, and yield new and more accurate est…
Detection of spatial variations in the (D/H) ratio in the local interstellar medium
Vidal-Madjar, Alfred; Koester, Detlev; Ferlet, Roger +6 more
We present high resolution (Delta lambda = 3.7 km.s^{-1}) HST-GHRS observations of the DA white dwarf G191-B2B, and derive the interstellar D/H ratio on the line of sight. We have observed and analysed simultaneously the interstellar lines of Hi, D i, N i, O i, Si ii and Si iii. We detect three absorbing clouds, and derive a total Hi\ column densi…