Fact Sheet
Nova
Astronomers may have to revise their theories about novae after seeing images like this one of T Pyxidis, a star that regularly ejects gas into space in brilliant explosions. The color-enhanced Hubble Space Telescope image shows that debris from the star’s eruptions have formed a halo of gaseous blobs around the unstable star rather than a smooth shell of gas as had been seen with ground-based telescopes. Eight concentric rings of stellar shrapnel spanning about one light-year have formed around the star, each one perhaps marking a boundary between the slow-moving debris of an older eruption and the fast-moving debris of a more recent one. Astronomers hope to use the rings to learn more about the star’s previous eruptions, which have been observed about every 20 years. Novae occur when white dwarfs like T Pyxidis have stolen so much hydrogen gas from their binary companion (in this case, a red dwarf) that the gas explodes, temporarily increasing the white dwarf’s brightness.
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