IUE observations of X Per, the proposed optical counterpart of the X-ray source 4U 0352+30.

Abstract

The O 9.5 (III-V) pe star X Persei, proposed optical counterpart of the X-ray source 4U 0352+30, has been observed on October 14, 1978, with the SWP Camera on board the IUE satellite in the low and high resolution modes. The ultraviolet continuum, in the range 1000-1900 A, can adequately be fitted to the emergent flux from a model atmosphere having 7; 30,000 K, in agreement with the spectral type of the star. The Si iv and C iv resonance lines show the presence of a dense envelope around the star, expanding with a terminal velocity of 650 km s^-1. The mass loss rate is estimated of the order of 10^-9 M_sun/yr. Comparison with previous results obtained by means of IUE suggests that fluctuations both in velocity and in mass loss rate might occur in the envelope of this star.