Ultraviolet Photometry from the Orbiting Astronomical Observatory. II. Interstellar Extinction

Interstellar extinction curves over the region XX36( 100 for 17 stars are presented. The observations were made by the two Wisconsin spectrometers on board the Orbiting Astronomical Observatory 2, with spectral resolutions of 10 and 20 A. The extinction curves generally show a pronounced maximum at X2175 + 25 a broad minimum in the region XX180O1350, and finally a rapid rise to the far-ultraviolet Large extinction variations from star to star are found, especially in the far-ultraviolet; however, with only two possible exceptions in this sample, the wavelength at the maximum of the extinction bump is essentially constant. These data are combined with visual and infrared observations to display the extinction behavior over a range in wavelength of about a factor of 20. The observations appear to require a multicomponent model of the interstellar dust.