Mintaka

Mintaka is a star some 1,200 light years distant in the constellation Orion. It has a Bayer designation of Delta Orionis (δ Ori) and a Flamsteed designation of 34 Orionis. The name Mintaka comes from منطقة manṭaqa, which means "the belt" in Arabic. Together with Alnitak (Zeta Orionis) and Alnilam (Epsilon Orionis), the three stars make up the belt of Orion, known by many names among ancient cultures. When Orion is close to the meridian, Mintaka is the right-most of the belt's stars as seen by an observer in the Northern Hemisphere facing south.

Observational history

Mintaka is the westernmost of the three stars of Orion's belt. It is easily visible to the naked eye, one of the brightest stars in the sky, and has been known since antiquity.

Radial velocity measurements taken by Henri-Alexandre Deslandres at Paris Observatory showed that Mintaka had a variable radial velocity and therefore was a spectroscopic binary. His preliminary orbital period estimate of 1.92 days was shown to be incorrect in 1904 when Johannes Franz Hartmann using photographic plates taken at Potsdam Observatory showed that the orbital period was 5.7 days. Hartmann also noticed that the calcium K line at 393.4 nanometres in the stellar spectrum did not share in the periodic displacements of the lines due to orbital motion of the star and theorized that there was a cloud in the line of sight to Mintaka that contained calcium. This was the first detection of the interstellar medium.