Theta_Arietis
Theta Arietis
Binary star system in the constellation Aries
Theta Arietis, Latinised from θ Arietis, is the Bayer designation for a binary star[7] system in the northern constellation of Aries. It is faintly visible to the naked eye with an apparent visual magnitude of 5.58.[2] With an annual parallax shift of 7.61 mas,[1] the distance to this star is an estimated 429 light-years (132 parsecs) with a 10-light-year margin of error. It is drifting further away with a radial velocity of +6 km/s.[2]
The primary, component A, is a white-hued, A-type main-sequence star with a stellar classification of A1 Vn.[3] It is spinning at a rapid pace as shown by the projected rotational velocity of 186 km/s.[10] This is causing the "nebulous" appearance of the absorption lines indicated by the 'n' suffix in the classification. In 2005, C. Neiner and associates classified this as a Be star because is displays emission features in the hydrogen Balmer lines.[5]
In 2016, a solar-mass companion was reported in close orbit around this star, based on observations using adaptive optics with the Gemini North Telescope.[7]