Glossary term: Nova

Description: A nova is a star that suddenly brightens, becoming many times brighter than before. The name derives from the Latin nova stella or new star, which was used in early-Modern Europe to describe bright stars that suddenly appeared in the sky. Novae have been observed as "guest stars" by many different cultures.

Novae are caused by white dwarfs which accrete gas from a close binary star companion. This gas builds up in the white dwarf's atmosphere until it is hot enough to ignite through nuclear fusion. This nuclear fireball causes the white dwarf to brighten by several orders of magnitude. Unlike a Type Ia supernova, the white dwarf remains intact after this explosion. This means that the whole process can start again and the nova can recur.

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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".