Delta Orionis - Mintaka

Delta Orionis, traditionally known as Mintaka (from "mantaqah", which means "belt" in Arabic), is the westernmost star in the Belt of Orion. The others are Zeta Orionis (Alnitak) and Epsilon Orionis (Alnilam). At magnitude 2.21, Mintaka is the seventh brightest star in Orion, and the faintest of the three belt stars. Mintaka is closest bright star to the celestial equator, only a quarter of a degree to the south.

Mythology

The three belt stars were collectively known by many names in many cultures. Arabic terms include "Al Nijad" (the Belt), "Al Nasak" (the Line), "Al Alkat" (the Golden Grains), and, in modern Arabic, "Al Mizan al Hakk" (the Accurate Scale Beam). In Chinese mythology, they were also known as The Weighing Beam as well as "Shen Xiu" (the Three Stars mansion), one of the 28 mansions of the Chinese constellations. In pre-Christian Scandinavia, the belt was known as Freyja's distaff (Friggerock). Vainamoinen's Scythe (Kalevala) and Kalevan Sword are terms from Finnish mythology. European biblically derived terms,were Jacob's Staff and Peter's Staff, as well as the Three Magi or Three Kings. The Seri people of northwestern Mexico call the three belt stars "Hapj" (a name denoting a hunter) which consists of "Hap" (mule deer), "Haamoja" (pronghorn), and "Mojet" (bighorn sheep).

Properties

Mintaka is a multiple star system some 900 light years away. Its components are a bluish-white primary of magnitude 2.23, and a pale blue secondary of 7th magnitude, about 52" away from the main component. Between them is a vastly dimmer 14th magnitude component. The main component itself is also double, consisting of a class B giant and a smaller but hotter class O main sequence star. These two stars are both about 70,000 times as luminous as the Sun, with a mass of some 20 solar masses, and orbit each other every 5.73 days. The stars eclipse each other slightly, dipping about 0.2 magnitudes during each orbit.

In 1904, the German astronomer Johannes Hartmann discovered absorptions in Mintaka's spectrum that could not be produced by the orbiting pair. From this discovery, and others that followed, we now know that interstellar space contains an enormously complex medium of gas and dust. The interstellar medium is the birthplace of new stars, and also (in the case of Mintaka) their graveyard: both of its components are so massive that they will eventually explode as supernovae.

[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]