UV upturn in elliptical galaxies: Theory

The UV upturn phenomenon found in bright elliptical galaxies has notable implications for stellar evolution, galaxy evolution and even for cosmology. The recent space observations of three galaxy clusters made by Brown and his collaborators shed great lights on this field of study. Theoretical models are being improved based on such data. While the core-helium burning stars remain the strongest candidate for the UV upturn, there is a growing concern that the canonical models may be missing important elements, such as binaries. I review the current theoretical understanding and future prospects.