EntityQ1504097· pop 15· linked from 236 articlesStrömgren sphereSign in to savesphere of ionized hydrogen around a young star of the spectral classes O or BConnectionsionizationEntitystarEntityhydrogenEntityelectronEntitygasEntitytemperatureEntityprotonEntitykelvinEntityultraviolet radiationEntityelectromagnetic radiationEntitymass densityEntityphotonEntityastrophysicsEntitysupernovaEntitydigital object identifierEntitynucleonEntitystar clusterEntityinterstellar mediumEntitybibcodeEntityH II regionEntityCategories1939 in scienceConcepts in astrophysics