النظام

Alnilam's absolute magnitude of −7.22 ranks it among the most intrinsically luminous stars on record, a beacon whose light travels nearly 1,977 light-years to reach Earth yet still arrives at apparent magnitude 1.69. It is Epsilon Orionis, the central star of Orion's Belt, and a blue-white B-type star with a negative B–V index of −0.184. Sitting almost exactly on the celestial equator at declination −1°, Alnilam is visible worldwide. Its enormous distance combined with unbroken brilliance illustrates how only the most powerful stars can remain conspicuous across such reaches of space, flanked in the Belt by Alnitak and Mintaka.