Hopkins Ultraviolet Telescope Observations of Six E and S0 Galaxies
Session 20 -- Astro 2
Display presentation, Tuesday, June 13, 1995, 9:20am - 6:30pm

## [20.04] Hopkins Ultraviolet Telescope Observations of Six E and S0 Galaxies

T.M.Brown (JHU), H.C.Ferguson (STScI), A.F.Davidsen (JHU)

In order to better understand the hot stellar populations of E and S0 galaxies, we observed six objects using the Hopkins Ultraviolet Telescope. Through our 11\arcsec\ $\times$ 60\arcsec\ aperture, we obtained one observation each of M~49 (1346~s), M~87 (950~s), M~89 (1682~s), and NGC~3115 (1634~s), two observations of NGC~3379 (3074~s), and four observations of M~60 (5824~s). The far-ultraviolet (FUV) spectra were obtained during orbital night as part of the Astro-2 mission on the space shuttle \it Endeavor \rm in March 1995, and cover the spectral range of 912 \AA\ to 1850 \AA\ with a resolution of 2--4 \AA. This sample quadruples the number of early-type galaxies studied to the Lyman limit.

After correcting for geocoronal emission and interstellar extinction in our own Galaxy, all the spectra are similar, even though the UV upturn'' strength, as characterized by the parameter $m_{1550}-V$, varies over the range of 2.04~mag to 3.86~mag for these galaxies. Comparison with models of evolved stellar populations confirms the conclusion from Astro-1 data that the FUV flux can be explained by stars with a narrow range of temperature and envelope mass on the extreme horizontal branch (EHB).

This work was supported by NASA contract NAS 5-27000 to the Johns Hopkins University.