Background emissions from an object in this constellation led Johannes Hartmann to discover the interstellar medium, and ionized emissions within it are responsible for Barnard's Loop. An active site of stellar formation within this constellation, the Molecular Cloud Complex, houses the Flame Nebula as well as the Horsehead Nebula. Mintaka, Alnilam, and the brightest O star, Alnitak, form a distinctive linear asterism in this constellation. Bellatrix and Rigel are particularly bright stars here, and its star Betelgeuse forms the shoulder of its namesake hunter. For 10 
Background emissions from an object in this constellation led Johannes Hartmann to discover the interstellar medium, and ionized emissions within it are responsible for Barnard's Loop. An active site of stellar formation within this constellation, the Molecular Cloud Complex, houses the Flame Nebula as well as the Horsehead Nebula. Mintaka, Alnilam, and the brightest O star, Alnitak, form a distinctive linear asterism in this constellation. Bellatrix and Rigel are particularly bright stars here, and its star Betelgeuse forms the shoulder of its namesake hunter. For 10 points, identify this constellation with notable asterisms like its Shield and Belt.
Background emissions from an object in this constellation led Johannes Hartmann to discover the interstellar medium, and ionized emissions within it are responsible for Barnard's Loop.
{Orion}