Psi¹ Orionis

Psi¹ Orionis lies close to Orion's Belt, and indeed an imaginary line north and west through the three stars of the Belt leads close to this blue star, though it is far fainter than any of Orion's three prominent Belt-stars. It lies less then two degrees from the star Psi² Orionis that shares its Bayer designation, but in reality the two stars are unconnected: Psi¹ is about 1,100 light years from Earth, while Psi² is more than 300 light years farther away.

The star itself is belongs to the B-type, or Blue, spectral classification, and is an eruptive variable of the Gamma Cassiopeiae type. Stars of this kind rotate rapidly on their axes, expelling material from their equatorial regions and sometimes even forming belts, rings or discs of matter within their stellar systems. These eruptions of matter cause unpredictable variations in the star's magnitude, which in the case of Psi¹ Orionis can shift between +4.92 and +4.96.