Phi Persei is spectroscopic binary consisting of a blue main sequence primary of class B2 and a hot subdwarf secondary.

There are no eclipses, but models of the system show that the disk significantly obscures the primary star.

It is proposed that it is the core of a 7 M☉ star, with the outer layers stripped as it expanded away from the main sequence.

[5] Phi Persei is a variable star with both rapid and longterm variations in its brightness and spectrum.

Consequently, the Chinese name for φ Persei itself is 天大將軍二 (Tiān Dà Jiāng Jūn èr, English: the Second Star of Heaven's Great General.).