Beta Canis Minoris

Beta Canis Minoris (β CMi, β Canis Minoris) is a star in the constellation of Canis Minor. In the night sky it is notable for its proximity to the prominent star Procyon. It has the traditional name Gomeisa, which comes from the Arabic al-ghumaisa’ "the bleary-eyed (woman)", short for مرزم الغميصاء mirzam al-ghumaisa’ "girdle of the bleary-eyed one". In Arabic, the short form would be identical with the name of Procyon.

In Chinese, 南河 (Nán Hé), meaning South River, refers to an asterism consisting of β Canis Minoris, Procyon and ε Canis Minoris. Consequently, β Canis Minoris itself is known as 南河二 (Nán Hé èr, English: the Second Star of South River.)

Properties

From parallax measurements, the distance to this star is about 162 light-years (50 parsecs). It has an apparent visual magnitude of 2.89, making it easily visible to the naked eye. Beta Canis Minoris has about 3.5 times the Sun's mass and is rotating rapidly with a projected rotational velocity of 210 km s⁻¹, which gives a lower bound on the azimuthal rotational velocity along the star's equator. The actual rotation rate may be about once per day.