Hotstars

Hotstars is a term used in astronomy to describe stars with high surface temperatures and luminosities, typically corresponding to spectral types O and B. These stars have surface temperatures ranging roughly from 15,000 to over 40,000 Kelvin and emit most of their radiation in the ultraviolet. Their high temperatures give them a blue or blue-white appearance and make them some of the most energetic objects in galaxies.

Physically, hotstars are usually massive, with masses from about eight solar masses up to several tens or more. They possess strong radiation pressure, which drives powerful stellar winds and results in significant mass loss over their short lifetimes. Their interiors are characterized by rapid energy production through hydrogen fusion, and their luminosities can reach hundreds of thousands of times that of the Sun.

Formation and evolution are rapid compared with lower-mass stars. Hotstars form in dense regions of giant molecular clouds and burn their hydrogen fuel in only a few million years. Because of their high masses, they exhaust their nuclear fuel quickly and end dramatically, most commonly in core-collapse supernovae or, for some very massive stars, direct collapse to black holes. Their ejecta contribute substantially to the chemical enrichment of the interstellar medium.

In their environments, hotstars play a crucial role in feedback processes. Their intense ultraviolet radiation ionizes surrounding gas, creating H II regions and influencing subsequent star formation. Winds and supernova explosions inject energy and heavy elements into the galaxy, shaping the evolution of star clusters and galaxies. Observationally, hotstars serve as tracers of recent star formation and are key inputs in models of stellar populations.

Examples include hot, luminous O- and B-type stars found in OB associations and star-forming regions in the Milky Way and nearby galaxies.