USS NOVA Namesake: Difference between revisions

When a white dwarf has a close companion star, the companion will often begin to have its outer atmosphere drawn away from it by the white dwarf's gravity as the companion star ages and expands into a red giant.  The captured gases consist primarily of hydrogen and helium, the two principal constituents of matter in the universe.  The gases are compacted on the white dwarf's surface by its enormous gravity, compressed and heated to enormous temperatures as additional material is drawn in.  Eventually, the pressures and temperatures within the hydrogen layer becomes great enough to trigger a nuclear fusion reaction that rapidly converts a large amount of the hydrogen into helium and other heavier elements.

A white dwarf can potentially generate multiple novae over time as additional hydrogen continues to accrete onto its surface from its companion star.  An example is RS Ophiuchi, which is known to have flared five times (in 1898, 1933, 1958, 1967, and 1985).  Eventually, however, either the companion star will either run out of material, or the white dwarf will undergo a nova so powerful that it is completely destroyed in the process.  This is somewhat similar to a type Ia supernova.  Supernovae in general, however, involve different processes as well as much higher energies, and should not be confused with ordinary novae.