{"@context":{"ns0":"http://www.ivoa.net/rdf/uat#","rdf":"http://www.w3.org/1999/02/22-rdf-syntax-ns#","owl":"http://www.w3.org/2002/07/owl#","skos":"http://www.w3.org/2004/02/skos/core#","metadata_def":"http://data.bioontology.org/metadata/def/","ns1":"http://astrothesaurus.org/uat/"},"@graph":[{"@id":"ns0:o-stars","@type":["owl:NamedIndividual","skos:Concept"],"skos:prefLabel":"O stars","skos: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.","metadata_def:mappingLoom":"ostars","metadata_def:mappingSameURI":{"@id":"ns0:o-stars"},"skos:exactMatch":{"@id":"ns1:1137"},"skos:broader":[{"@id":"ns0:early-type-stars"},{"@id":"ns0:stellar-spectral-types"}],"skos:related":{"@id":"ns0:stellar-classification"}},{"@id":"ns0:stellar-classification","skos:related":{"@id":"ns0:o-stars"}},{"@id":"ns0:o-dwarf-stars","skos:broader":{"@id":"ns0:o-stars"}},{"@id":"ns0:o-giant-stars","skos:broader":{"@id":"ns0:o-stars"}},{"@id":"ns0:o-subdwarf-stars","skos:broader":{"@id":"ns0:o-stars"}},{"@id":"ns0:o-subgiant-stars","skos:broader":{"@id":"ns0:o-stars"}},{"@id":"ns0:o-supergiant-stars","skos:broader":{"@id":"ns0:o-stars"}},{"@id":"ns0:oe-stars","skos:broader":{"@id":"ns0:o-stars"}},{"@id":"ns0:oef-stars","skos:broader":{"@id":"ns0:o-stars"}},{"@id":"ns0:of-stars","skos:broader":{"@id":"ns0:o-stars"}}]}