Algol — Stella variabile in Perseo

ADS 2362A is the prototype Algol star, first discovered as variable by Montanari in 1669. The first period determined by | Goodricke in 1783, who also interpreted the variations as due to eclipses. The prototype star proves to be a more | a complicated system than most of the Algol-type stars, i.e., compact triple system with separation of the components | well under 0.1". The components usually designated Algol A, B, C, sometimes A, a, P. Two formerly additionally desig- | nated components D and E, inferred on the basis of an apparent 32 year apsidal motion, are now considered spurious. | The various Algol components must not be confused with the visual components ADS 2362 B-E, optical companions at much | greater distances from A. ADS 2362A, EA 2.12 - 3.40V, 2.86732442d, abrupt period changes. Orbital and rotation periods | synchronized. Rotational velocity 65k/s. Radio flares extending to about 1 A.U., not associated with X-ray activity. | Radio flare activity appears correlated with period discontinuities, attributed to "starquakes." Mass flow from K to B8 | component at rate of 1.8x10E-08 solar masses/year. Possible circumstellar material associated with radio or H alpha | emission.