Red Giant Survival

Astronomers have detected an exoplanet that most likely survived the red giant phase of its parent star. V391 Pegasi belongs to a class of subdwarf stars that vary in brightness every few minutes. Researchers noticed a regular variation in the timing of these pulsations, which indicates the presence of a planet at least 3.2 times the mass of Jupiter. The nature of subdwarfs implies that the planet once orbited about one Earth-sun distance, or astronomical unit (AU), from V391 Pegasi; the gap closed to 0.3 AU during the star's red giant phase. After V391 Pegasi lost its outer mass to become a dwarf—it has shrunk from 0.9 to 0.5 solar mass—the planet migrated farther away.

The finding, which arguably supports the theory that Earth might survive the sun's red giant phase (as it might appear in the illustration), is in the September 13 Nature.

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