42 Persei
42 Persei is a binary star system in the northern constellation of Perseus. It has the Bayer designation n Persei, while "42 Persei" is the Flamsteed designation. The system is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of 5.11. It is located around distant from the Sun, but is drifting closer with a radial velocity of −12.4 km/s.

42 Persei is a single-lined spectroscopic binary with an orbital period of 1.77 days and an eccentricity of just 0.056. It is a variable star, ranging in brightness from magnitude 5.05 to 5.18, and was assumed at discovery to be a close, but detached, eclipsing variable. Closer studies of the light variations and the orbit have shown that the main brightness changes are due to rotation of the distorted primary star, although it is predicted from the likely inclination of the orbit that shallow eclipses could also occur.

The visible component is an A-type main-sequence star with a stellar classification of A3V; a star that is fusing its core hydrogen. It has been reported as a mild Am star, but this is considered questionable. The star has twice the mass of the Sun and 3.5 times the Sun's radius. It has a high rate of spin, showing a projected rotational velocity of 91 km/s. The star is radiating 59 times the luminosity of the Sun from its photosphere at an effective temperature of 8,892 K. The unseen companion star is likely to be a dim red dwarf with 38% of the Sun's mass.

In Chinese astronomy, 42 Persei is called 天讒, Pinyin: Tiānchán, meaning "Celestial Slander", because this star is marking itself and stand alone in "Celestial Slander" asterism, Hairy Head mansion (see : Chinese constellation).
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binary star
Concept
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constellation
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Perseus
CEL
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Bayer designation
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Flamsteed designation
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apparent visual magnitude
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radial velocity
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spectroscopic binary
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eccentricity
Concept
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eclipsing variable
Concept
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A-type main-sequence star
Concept
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stellar classification
Concept
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core
Concept
Q556
hydrogen
Concept
Q451152
Am star
Concept
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mass of the Sun
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Sun's radius
Concept
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projected rotational velocity
Concept
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luminosity of the Sun
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red dwarf
Concept
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Chinese astronomy
Concept
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Pinyin
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Hairy Head
CEL
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Chinese constellation
Concept
Q3599099
42 Persei
CEL
Q3599099
42 Persei
CEL
Q3599099
42 Persei
CEL
Q3599099
42 Persei
CEL
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constellation
apparent magnitude
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