Hot Subdwarfs
Hot subdwarfs, of spectral types O and B, also termed "extreme horizontal branch stars" are an entirely different class of objects to cool subdwarfs. These stars represent a late stage in the evolution of some stars, caused when a red giant star loses its outer hydrogen layers before the core begins to fuse helium. The reasons why this premature mass loss occurs are unclear, but the interaction of stars in a binary star system is thought to be one of the main mechanisms. Single subdwarfs may be the result of a merger of two white dwarf stars. Subdwarf B stars, being more luminous than white dwarfs, are a significant component in the hot star population of old stellar systems, such as globular clusters and elliptical galaxies.
Read more about this topic: Subdwarf Stars
Famous quotes containing the word hot:
“The fact that the mental health establishment has equated separation with health, equated women’s morality with soft-heartedness, and placed mothers on the psychological hot seat has taken a toll on modern mothers.”
—Ron Taffel (20th century)