Upsilon Aurigae

Upsilon Aurigae, Latinized from υ Aurigae, is the Bayer designation for a star in the northern constellation of Auriga. It has an apparent visual magnitude of 4.74, which means it is bright enough to be seen with the naked eye. Based upon parallax measurements made during the Hipparcos mission, this star is approximately distant from the Earth.
This is an evolved red giant star with a stellar classification of M0 III. It is a suspected variable star and is currently on the asymptotic giant branch, which means it is generating energy at its core through the fusion of helium. The measured angular diameter of this star, after correction for limb darkening, is . At the estimated distance of Upsilon Aurigae, this yields a physical size of about 73 times the radius of the Sun.
References.
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