Mintaka (Delta Orionis)


Mintaka is at the upper left. Credit: Digitized Sky Survey, ESA/ESO/NASA FITS Liberator.

Mintaka (Delta Orionis) is the seventh brightest star in the constellation Orion and the westernmost and faintest star in Orion's Belt; its Arabic name means "the belt of the Central One." Mintaka is a multiple star system, the main components of which are a hot (30,000 K) B star and an even hotter O star, each with a mass of over 20 solar masses and a luminosity 70,000 times that of the Sun. These bright stars form a compact visual binary, with a period of 5.73 days and a maximum separation of 0.3", and also an Algol star system showing a dip of about 0.2 magnitude during mid-partial eclipse. Two much dimmer and remote companions trek around the central O-B couple. A magnitude 6.8 B star orbits at a distance of about 0.25 light-year, while, closer in, circles a magnitude 14 component.


Mintaka is famous as a background against which the thin gas of interstellar space was first detected, when the German astronomer Johannes Hartmann (1865-1936) in 1904 discovered absorption in the star's spectrum that could not be produced by the orbiting pair.


visual magnitude 2.25
absolute magnitude -4.99
spectral type O9.5II + B2V
distance 916 light-years
position R.A. 05h 32m 0.4s,
Dec. -00� 17' 57"