ar X iv : a st ro - p h / 98 05 00 5 v 1 1 M ay 1 99 8 1 ULTRAVIOLET ISOTROPIC EMISSION FROM THE BLAZAR

ar X iv : a st ro - p h / 92 05 00 5 v 1 9 M ay 1 99 2 UCSBTH – 92 – 05 April 1992 CHAOTIC DARK MATTER

A very weakly coupled scalar field with mass m and initial vacuum expectation value V will provide enough mass to close the universe provided V ≃ (3 × 10 8 GeV)(100 GeV/m) 1/4. We discuss possible models in which such a field could arise. (a) Electronic address (internet): [email protected].

ar X iv : a st ro - p h / 98 05 04 7 v 1 6 M ay 1 99 8 The energy distribution of β CrB for the specific stellar abundances

The comparison of the observed and computed energy distributions of β CrB has shown that a model with the specific chemical composition of the star can account for the visual enery distribution, while it is still unable to reproduce ultraviolet observations shortward of 1700Å. Furthermore, the predicted absorption of strong Fe ii and Mg ii UV lines is much larger than the observed one.

ar X iv : a st ro - p h / 95 05 14 5 v 1 3 1 M ay 1 99 5 Search for GRB counterparts

ar X iv : a st ro - p h / 98 05 21 3 v 1 1 5 M ay 1 99 8 Light element abundances in He - rich stars

We present an abundance analysis of light elements in He-rich stars. The analysis is based on both low and high resolution observations collected at ESO, La Silla, Chile in the optical region and includes 6 standards and 21 He-rich stars. Light-element abundances display a diverse pattern: they range from under-solar up to above-solar values.

ar X iv : a st ro - p h / 98 05 20 5 v 1 1 5 M ay 1 99 8 The double - lined spectroscopic binary α Andromedae : orbital elements and elemental abundances

We performed a spectroscopic study of the SB2 Mercury-Manganese star α And. Our measurements of the secondary’s radial velocities result in improved orbital elements. The secondary shows abundances typical of the metallic-line stars: a Ca deficiency, small overabundances of the iron-peak elements, and 1.0 dex overabundances of Sr and Ba.