Are Analogues of Hot Subdwarf Stars Responsible for the UVX Phenomenon in Galaxy Nuclei?

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dc.creatorDorman, Ben
dc.creatorO'Connell, R. W.
dc.creatorRood, R. T.
dc.date1994-02-18
dc.date.accessioned2026-07-07T02:19:05Z
dc.date.available2026-07-07T02:19:05Z
dc.descriptionWe present the case that populations of sdB/sdOB/sdO-type stars may be a common constituent of galactic stellar populations, responsible for the UV upturn (`UVX') observed in the spectra of spiral bulges and normal galaxy nuclei. Extreme Horizontal Branch stars with $\log g > 5$ and $\log \teff > 20,000K$ have emerged in the last few years as the most likely candidate for the origin of the UVX. The magnitude of this far-UV flux in some systems (e.g. NGC~1399, NGC~4649) indicates that galactic nuclear regions must contain larger numbers of these subdwarfs than does the solar neighbourhood. This paper summarizes the results of a quantitative study of the UV radiation from evolved stellar populations. We have computed a large grid of stellar models in advanced stages of evolution, as well as a set of isochrones for ages 2-20 Gyr, for a wide range in composition. We use these calculations to derive synthetic UV colour indices for stellar populations with hot components.
dc.descriptionTo appear in `Hot Stars in the Halo' ed. S.J. Adelman (CUP 1994) (uuencoded compressed Postscript file, 12pp.)
dc.identifierhttps://arxiv.org/abs/astro-ph/9402046
dc.identifierhttp://arxiv.org/abs/astro-ph/9402046
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/9728
dc.subjectAstrophysics
dc.titleAre Analogues of Hot Subdwarf Stars Responsible for the UVX Phenomenon in Galaxy Nuclei?
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