Showing papers by "Alan Fitzsimmons published in 1990"

The chemical composition of a main-sequence star in the Small Magellanic Cloud

Abstract: High-resolution echelle spectra of a main-sequence B type star (AV 304) in the Small Magellanic Cloud are analyzed using model atmosphere techniques to derive its atmospheric parameters and chemical composition. Because AV 340 is at an early evolutionary stage, its chemical composition should reflect that of its progenitor interstellar material. A general heavy element depletion of approximately -0.6 to -0.8 dex is deduced with nitrogen being more severely depleted and oxygen possibly less depleted. Helium has an approximately normal abundance. The high quality of the observational data coupled with the very small projected rotational velocity implies that depletions should normally be accurate to better than + or - 0.2 dex, with the oxygen abundance probably being accurate to + or - 0.1 dex. 43 refs.

Narrow-band photometry of Comet P/Halley - OH and H2O scalelengths and pre-perihelion production rates

Abstract: Les observations photometriques de la comete de Halley au post-perihelion , du 7 au 10 decembre 1985, sont presentees. Les taux de production et les largeurs d'echelle des molecules OH et H 2 O du noyau sont determinees.

Spectra of Six Asteroids Obtained at La-Palma

Abstract: Les spectres de 6 asteroides, 624 Hektor, 153 Hilda, 279 Thule, 334 Chicago, 1269 Rollandia et 1167 Dubiago, sont presentes. Des caracteristiques d'absorption sont determinees dans les spectres de facteur de reflexion de 1269 Rollandia et 279 Thule.

The chemical composition of the northern double cluster H and KHI Persei and the loose association Cepheus OB III.

Abstract: Les observations spectroscopiques des amas doubles h et χ Per et de l'association lointaine Cep OB III sont presentees. Les largeurs equivalentes, les profils de raies et les abondances (calculees avec un modele d'atmosphere ETL) des etoiles (proches) de la sequence principale sont determines.