2002ApJ...568L..19B

We present far-UV spectroscopy of the giant elliptical galaxy NGC 1399, obtained with the Far Ultraviolet Spectroscopic Explorer. Of all quiescent ellipticals, NGC 1399 has the strongest known ``UV upturn''–a sharp spectral rise shortward of 2500 Å. It is now well established that this emission comes from hot horizontal branch stars and their progeny; however, the chemical composition of these stars has been the subject of a longstanding debate. For the first time in observations of any elliptical galaxy, our spectra clearly show photospheric metallic absorption lines within the UV upturn. The abundance of N is at 45% solar, Si is at 13% solar, and C is at 2% solar. Such abundance anomalies are a natural consequence of gravitational diffusion. These photospheric abundances fall in the range observed for subdwarf B stars of the Galactic field.

Although NGC 1399 is at the center of the Fornax Cluster, we find no evidence for O VI cooling flow emission. The upper limit to λλ1032, 1038 emission is 3.9x10^–15 ergs.s^–1.cm^–2, equivalent to 0.14 M_☉ yr^–1 and less than the value predicted by simple cooling flow models of the NGC 1399 X-ray luminosity.