In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

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.
Science