This constellation's gamma star is the bright eruptive variable Bellatrix. 
This constellation's gamma star is the bright eruptive variable Bellatrix. A better-known star in it has been observed shrinking for the past fifteen years. This constellation contains Barnard's loop, as well as the tight open cluster Trapezium and a namesake nebula, M42, though its best known deep space object is the Horsehead Nebula. An asterism in this constellation is formed by the three stars Alnitak, Alnilam, and Mintaka, this figure's "belt." For 10 points, name this constellation whose brightest star is Rigel but whose alpha star is Betelgeuse, the Hunter.
This constellation's gamma star is the bright eruptive variable Bellatrix.
Orion