Lambda Ursae Majoris

Lambda Ursae Majoris (Lambda UMa, λ Ursae Majoris, λ UMa) is a star in the northern circumpolar constellation of Ursa Major. It has the proper names Tania Borealis (former Tania borealis).

This star has an apparent visual magnitude of +3.45, making it one of the brighter members of the constellation. The distance to this star has been measured directly using the parallax technique, which yields a value of roughly 138 light-years (42 parsecs) with a 4% margin of error. The stellar classification of Lambda Ursae Majoris is A2 IV, with the luminosity class of 'IV' indicating that, after 410 million years on the main sequence, this star is in the process of evolving into a giant star as the supply of hydrogen at its core becomes exhausted. Compared to the Sun it has 240% of the mass and 230% of the Sun's radius, but is radiating 37 times as much luminosity. This energy is being emitted from the star's outer atmosphere at an effective temperature of 9,280 K, giving it the characteristic white-hot glow of an A-type star.