FAR-ULTRAVIOLET STELLAR PHOTOMETRY: FIELDS IN SAGITTARIUS AND SCORPIUS

Authors

• Edward G. Schmidt, University of Nebraska-LincolnFollow
• George R. Carruthers, E.O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, DC

Document Type

Article

Date of this Version

February 1995

Comments

Published inThe Astrophysical Journal Supplement Series 96, pp.605-626 (February 1995). Published by the University of Chicago Press; copyright © 1995 American Astronomical Society; reproduced by permission of the AAS.http://www.noao.edu/apjsup/apjsup.html

Abstract

Far-ultraviolet photometry for 741 objects in a field in Sagittarius centered near M8 and 54 1 objects in a field centered near ζ Scorpii is presented. These data were extracted from electrographic images obtained with two cameras during a shuttle flight in 1991 April/May. The cameras provided band passes with λ_eff= 1375 Å and λ_eff= 1781 Å. Synthetic colors show that these bands are sensitive to effective temperature for hot stars. Our measurements were placed on a quantitative far-ultraviolet magnitude scale by convolving the spectra of stars observed by IUE with our cameras' spectral response functions. Fifty-eight percent of the ultraviolet objects were identified with visible stars using the SIMBAD database while another 40% of the objects are blends of early type stars too close together to separate with our resolution. Our photometry is compared with that from the TD-I, OAO 2, and ANS satellites and the S20 1 (Apollo 16) far-ultraviolet camera and found to agree at the level of a few tenths of a magnitude. Unlike previous studies, almost half of the identified visual counterparts to the ultraviolet objects are early B stars. A plot of distance modulus against ultraviolet color excess reveals a significant population of stars with strong ultraviolet excesses.