OBSERVATIONS OF FAR-UV EMISSION FROM NGC-1275 WITH THE HOPKINS ULTRAVIOLET TELESCOPE

The galaxy NGC 1275 was observed with the Hopkins Ultraviolet Telescop e (HUT) during the Astro-1 space shuttle mission in 1990 December. NGC 1275 lies at the center of the Perseus cluster cooling dow and is sur rounded by a bright emission-line nebula. The galaxy's far-UV spectrum shows a faint continuum and emission from Lyman alpha lambda 1216, C IV lambda lambda 1548, 1551, and He II lambda 1640 at the redshift of the galaxy. The profile of the redshifted Ly alpha line is consistent with the multiple-component feature observed by Johnstone & Fabian wit h HST [MNRAS, 273, 625 (1995)]. The redshifted C IV line has both a br oad component due to the galactic nucleus and a narrow component that we associate with the surrounding nebula. We set an upper limit on the flux of O VI lambda lambda 1032, 1038 and find that the reddening-cor rected ratio I(O VI)/I(C IV)<1.3 is too low for a simple cooling flow, indicating that other processes must contribute to the diffuse C IV e mission. The I(O VI)/I(C IV) and I(Ly alpha)/I(C IV) ratios are consis tent with shock velocities between similar to 100 and 110 km s(-1), bu t the observed line luminosities cannot readily be accounted for by sh ock models. Models assuming either photoionization by a central source or turbulent mixing layers cannot produce the diffuse C IV emission. The continuum spectrum shows evidence of B-star emission from the high -velocity system. It is well fit by a model in which star formation ha s continued for at least 5x10(8) yr with a Salpeter IMF at a constant rate of 30 M. yr(-1), corresponding to a star-formation efficiency in the cooling flow of approximately 15%. (C) 1996 American Astronomical Society.