B型主序星
The primary component is a B-type main-sequence star with a stellar classification of B5V, indicating it is generating energy through core hydrogen fusion. The star is spinning with a projected rotational velocity of 75 km/s. It has 4.6 times the mass of the Sun and about 3.9 times the Sun's radius. HD 21278 is radiating 940 times the luminosity of the Sun from its photosphere at an effective temperature of 15,274 K.