<?xml version="1.0" encoding="UTF-8"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:ns0="http://www.ivoa.net/rdf/uat#" xmlns:owl="http://www.w3.org/2002/07/owl#" xmlns:skos="http://www.w3.org/2004/02/skos/core#" xmlns:metadata_def="http://data.bioontology.org/metadata/def/" xmlns:ns1="http://astrothesaurus.org/uat/"> <owl:NamedIndividual rdf:about="http://www.ivoa.net/rdf/uat#o-stars"> <rdf:type rdf:resource="http://www.w3.org/2004/02/skos/core#Concept"/> <skos:prefLabel>O stars</skos:prefLabel> <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.</skos:definition> <metadata_def:mappingLoom>ostars</metadata_def:mappingLoom> <metadata_def:mappingSameURI rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> <skos:exactMatch rdf:resource="http://astrothesaurus.org/uat/1137"/> <skos:broader rdf:resource="http://www.ivoa.net/rdf/uat#early-type-stars"/> <skos:broader rdf:resource="http://www.ivoa.net/rdf/uat#stellar-spectral-types"/> <skos:related rdf:resource="http://www.ivoa.net/rdf/uat#stellar-classification"/> </owl:NamedIndividual> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#o-dwarf-stars"> <skos:broader> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#o-stars"> <metadata_def:mappingSameURI rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> </rdf:Description> </skos:broader> </rdf:Description> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#o-giant-stars"> <skos:broader rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> </rdf:Description> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#o-subdwarf-stars"> <skos:broader rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> </rdf:Description> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#o-subgiant-stars"> <skos:broader rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> </rdf:Description> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#o-supergiant-stars"> <skos:broader rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> </rdf:Description> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#oe-stars"> <skos:broader rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> </rdf:Description> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#oef-stars"> <skos:broader rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> </rdf:Description> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#of-stars"> <skos:broader rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> </rdf:Description> <rdf:Description rdf:about="http://www.ivoa.net/rdf/uat#stellar-classification"> <skos:related rdf:resource="http://www.ivoa.net/rdf/uat#o-stars"/> </rdf:Description> </rdf:RDF>