By Ron Cowen
PASADENA, Calif. — Betelgeuse, one of the brightest stars visible to the naked eye, has shrunk in diameter by more than 15 percent since 1993.
The star, a red supergiant, has a radius exceeding the distance between the sun and Jupiter. The shrinkage corresponds to the star contracting by a distance equal to that between Venus and the sun, researchers reported June 9 at an American Astronomical Society meeting and in the June 1 Astrophysical Journal Letters.
No other red supergiant has shown such a dramatic contraction, though others stars known as Mira variables routinely contract or expand by an even greater amount in a single year.