Double Double

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The quadruple star Epsilon Lyrae. With binoculars, or even sharp eyesight, the star appears as a wide double of magnitudes 4.6 and 4.7 which form a genuine binary. Moderate-sized telescopes reveal that each star is itself double. The pair known as Epsilon1 consists of an A4 dwarf and an F1 dwarf of magnitudes 5.0 and 6.1, orbiting each other in a period of about 1725 years; the Epsilon2 pair consists of an A8 dwarf and an F0 dwarf, magnitudes 5.2 and 5.5, orbital period about 720 years. The four stars lie about 160 l.y. away.

Subjects: Astronomy and Astrophysics.

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