Concept information
Preferred term
O stars
Definition
- A luminous, hot, blue star whose spectrum is dominated by the lines of hydrogen, atomic helium, and ionized helium; also known as O-type star. This is the earliest spectral type and the only main sequence star in which ionized helium is present. The effective temperatures of these stars range from about 30,000 K to 50,000 K, their luminosities from 50,000 to 1,000,000 times that of solar luminosity, and their masses from about 20 to 100 solar masses. The hottest O-type stars display high ionization emission features such as N III and He II, Of star. They are divided into subtypes O2, the hottest, to O9.7, the coldest. O-type stars are relatively rare, for each star of 100 solar masses there are 10^6 stars of solar mass. They are relatively short-lived since they spend only a few million years on the main sequence. The brightest O-type star in the sky visible with naked eye is Alnitak. (en)
Broader concept
- Early-type stars (en)
- Stellar spectral types (en)
Narrower concepts
- O dwarf stars (en)
- Oef stars (en)
- Oe stars (en)
- Of stars (en)
- O giant stars (en)
- O subdwarf stars (en)
- O subgiant stars (en)
- O supergiant stars (en)
Entry terms
- Class O stars (en)
- O-type stars (en)
Editorial note
URI
http://astrothesaurus.org/uat/1137
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