Algol

This is Algol in the sky

English: Algol (β Persei) is a triple-star system (Algol A, B, and C) in the constellation Perseus. The large and bright primary Algol A is regularly eclipsed by the dimmer Algol B every 2.87 days. The pair is separated by only 0.062 astronomical units (AU) from each other, so close that Algol A is slowly stripping off Algol B's outer layers.

Algol, also known as the Demon Star, is a bright star in the Perseus constellation. It is one of the best known double stars that can only be seen in spectroscopes, the first star of its type discovered, and one of the first variable stars to be discovered before it explodes. Algol is made of three stars (Beta Persei A, B and C) and the brightest is Persei A. These stars partly eclipse each other every 2 days, 20 hours and 49 minutes for 10 hours.

Algol Media

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  The Algol system on 12 August 2009. This is a CHARA interferometer image with 1/2-milliarcsecond resolution in the near-infrared H-band. The elongated appearance of Algol Aa2 (labelled B) and the round appearance of Algol Aa1 (labelled A) are real, but the form of Algol Ab (labelled C) is an artifact.

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  Light curve of the Algol recorded by NASA's Transiting Exoplanet Survey Satellite (TESS).

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  Algol Aa2 orbits Algol Aa1. This animation was assembled from 55 images of the CHARA interferometer in the near-infrared H-band, sorted according to orbital phase. Because some phases are poorly covered, Aa2 jumps at some points along its path.

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  Interpolation of the orbit of Aa2 around Aa1 with focus on Aa1.

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  Algol is a bright star in the constellation of Perseus (upper right).