Omicron Ursae Majoris
Giant star with a confirmed exoplanet in Ursa Major.
Omicron Ursae Majoris is a star system in the northern circumpolar constellation Ursa Major. With an apparent visual magnitude of +3.35, it lies roughly 179 light-years from the Sun. In 2012, an exoplanet was discovered orbiting the primary star.
Quick Facts
- Bayer designation
- ο Ursae Majoris
- Apparent visual magnitude
- +3.35
- Distance from sun
- 179 ly
- Stellar classification
- G5 III
- Mass
- 3 times the Sun's mass
- Radius
- 14 times the Sun's radius
- Luminosity
- 116 times the Sun's luminosity
Facts from the source article.
Nomenclature
The Bayer designation for this star is ο Ursae Majoris, Latinised as Omicron Ursae Majoris. Its traditional name, Muscida, comes from the post-classical Latin musus, meaning 'snout' or 'muzzle of the bear', and was shared with the optical double star Pi Ursae Majoris. In 2016, the International Astronomical Union's Working Group on Star Names approved Muscida for this star. In Chinese astronomy, it belongs to an asterism called Inner Steps, which includes several other stars in Ursa Major.
Properties and observations
The stellar classification G5 III indicates this star is in the giant stage of evolution. Its angular diameter, measured by interferometry, is about 2.42 milliarcseconds, corresponding to a physical radius roughly 14 times that of the Sun. It has about three solar masses and radiates 116 times the Sun's luminosity, with an effective temperature of 5,282 K, giving it a yellowish hue typical of G-type stars. In 1963, East German astronomer Gerhard Jakisch reported variability with a 358-day period and 0.08 magnitude amplitude; the 1982 New Catalogue of Suspected Variable Stars listed a range from 3.30 to 3.36. However, in 1992 American astronomer Dorrit Hoffleit noted that the comparison stars used might themselves be variable, so the star's actual variability is suspect. A magnitude 15.2 common proper motion companion lies at an angular separation of 7.1 arcseconds, and with 99.4% probability is the source of the system's X-ray emission. Two other listed companions appear to be optical based on proper motion data, and no other companions were detected by 2016. This system is a member of the thin disk population, following an orbit with eccentricity 0.12 that brings it between 23.5 and 30.2 kly from the Galactic Center and no more than about 330 ly above the galactic plane. It is considered a runaway star due to a high peculiar velocity of 35.5 km/s relative to nearby stars. The star has no detectable magnetic fields.
More in Stars of Ursa Major
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