HD_21278
HD 21278
Binary star system in the constellation Perseus
HD 21278 is a binary star[7] system in the constellation Perseus, located within the 60±7[6] million year old Alpha Persei Cluster.[7] It has a blue-white hue and is visible to the naked eye with a combined apparent visual magnitude of 4.99.[2] The system is located at a distance of approximately 580 light years from the Sun based on parallax,[1] and it is drifting further away with a radial velocity of +1.20 km/s.[5]
The binary nature of this star was announced in 1925 by Otto Struve.[13] It is a double-lined spectroscopic binary with an orbital period of 21.7 days and an eccentricity of 0.12.[7]
The primary component is a B-type main-sequence star with a stellar classification of B5V,[3] indicating it is generating energy through core hydrogen fusion. The star is spinning with a projected rotational velocity of 75 km/s.[10] It has 4.6[8] times the mass of the Sun and about 3.9[9] times the Sun's radius. HD 21278 is radiating 940[6] times the luminosity of the Sun from its photosphere at an effective temperature of 15,274 K.[10]