A detailed study of a 6° diameter field in Scutum

Autor: Reichen, M., Lanz, T., Golay, M., Huguenin, D.
Zdroj: Astrophysics and Space Science; January 1990, Vol. 163 Issue: 2 p275-332, 58p
Abstrakt: A 6-deg diameter field centered on the star e Scutum has been selected from the SCAP-2000 balloon-borne UV survey for its high apparent stellar density contrast and relatively good transparency on a small projected portion of the galactic plane. In view of a detailed study of the absorption and interstellar matter distribution in this field, a large collection of data has been made and is presented here. Ultraviolet magnitudes at 2000 Å have been obtained from the reduction of three SCAP frames. In addition 322 stars among the 487 stars detected on the UV frames have been mesured in the Geneva photometric system. For a small number of photometrically distant objects, medium resolution spectra have been obtained in order to determine spectral types and confirm the distances determination. An overall description of the distribution of interstellar material in the ultraviolet is made using star counting methods, and is confronted to similar studies in the visible range. A discussion of the variations of the extinction law in different parts of the field is made. A new distance determination of the Sct OB2 asociation is proposed, as well as a list of additional probable members of the association. A certain number of distant hot stars seem to indicate the presence of an unknown OB association at the edge of the Scutum spiral, arm at a distance of over 3 kpc from the Sun.
Databáze: Supplemental Index