Mahasim (Theta Aurigae) -- Double Star in Auriga
Wrist of the Charioteer
Mahasim (Wrist of the Charioteer) is better known by its Greek-letter insignia, Theta Aurigae.
Mahasim is a prominent star in the constellation’s polygon outline and shines high overhead
in the winter sky.
From an astrophysics’ view point, Mahasim is one interesting star. It has an unusually strong
magnetic field (2,000x Earths) and has a patchy surface consisting of high-concentrations of
silicon, strontium, chromium along with additional Rare-Earth Elements. Because these
spectral anomalies are found in patches on the star’s surface, they vary in concentrations
when viewed-from-Earth during the star’s rotation. Mahasim is classified as an “A-Peculiar
Star”. More detailed information can be found on this strange star in “Annals of the Deep
Sky – Volume 2” by Kanipe & Webb.
From an amateur astronomer’s view point, Theta Aurigae is an intriguing double-star. With a
separation of 3.6 arcseconds, many assume it will be an easy split. But it is not. The primary
star is so much brighter than the secondary star that unless one has good optics and
stable/transparent skies the best one gets is a slight-bulge at the edge of Mahasim.
I was under an excellent sky, but clouds were already rising in the west soon to cover the sky.
Mahasim was my last telescopic object for the evening. Through the 155mm refractor at 243x
magnification, the two stars split cleanly without difficulty – a testimony to the quality of both the
telescope and the night sky.