Proper noun
Mesarthim
(astronomy) γ Arietis, a component of the star Gamma Arietis.
Aries is a relatively dim constellation, possessing only four bright stars: Hamal (Alpha Arietis, second magnitude), Sheratan (Beta Arietis, third magnitude), Mesarthim (Gamma Arietis, fourth magnitude), and 41 Arietis (also fourth magnitude). Source: Internet