Gamma Persei (Gamma Per, γ Persei, γ Per) is a binary star system in the constellation Perseus. The combined apparent visual magnitude of the pair is +2.9,[2] making it the fourth-brightest member of the constellation. The distance to this system is of roughly 221 light-years (68 parsecs) with a 1% margin of error.[6] About 4° to the north of Gamma Persei is the radiance point for the annual Perseid meteor shower.[11]
This is a wide eclipsing binary system with an orbital period of 5,329.8 days (14.6 years).[12] This eclipse was first observed in 1990 and lasted for two weeks.[13] During an eclipse, the primary passes in front of the secondary, causing the magnitude of the system to decrease by 0.55.[14] The primary component of this system is a giant star with a stellar classification of G9 III.[15] It has a projected rotational velocity of 50.0 km s−1 and a lengthy estimated rotation period of 14.6 years.[7] The classification of the secondary remains tentative, with assignments of A3 V[8] and A2(III).[15]
Mass estimates for the two stars remain disparate. Using speckle interferometry, McAlister (1982) obtained mass estimates of 4.73 M☉ for the primary and 2.75 M☉ for the secondary, where M☉ is the mass of the Sun. He noted that the mass estimate was too high for the given classification of the primary.[16] Martin and Mignard (1998) determined masses for both components based on data from the Hipparcos mission: 5.036 ± 0.951 M☉ for the primary and 2.295 ± 0.453 M☉ for the secondary. They admit that the high inclination of the orbit resulted in a large margin of error.[17] Prieto and Lambert (1999) came up with a mass estimate of 3.81 M☉ for the primary,[18] while Pizzolato and Maggio (2000) obtained 4.34 M☉.[7] Ling et al. (2001) obtained estimates of 2.7 M☉ for the primary and 1.65 M☉ for the secondary,[8] while Kaler (2001) obtained 2.5 and 1.9, respectively.[13] Diamant et al. (2023) found masses of 3.6 and 2.4 M☉ for A and B respectively.[9]
Name and etymology
- This star, together with δ Per, ψ Per, σ Per, α Per and η Per, has been called the Segment of Perseus.[19]
- In Chinese, 天船 (Tiān Chuán), meaning Celestial Boat, refers to an asterism consisting of γ Persei, η Persei, α Persei, ψ Persei, δ Persei, 48 Persei, μ Persei and HD 27084. Consequently, the Chinese name for γ Persei itself is 天船二 (Tiān Chuán èr, English: the Second Star of Celestial Boat.)[20]
References
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