Muscida (ο Ursae Majoris) Facts

Muscida, also designated as Omicron Ursae Majoris, is a star system in the northern constellation of Ursa Major, the great bear. Keep reading for comprehensive information and facts.

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Muscida, also designated as Omicron Ursae Majoris, is a star system in the northern constellation of Ursa Major, the great bear. Muscida also has an exoplanet orbiting around it.

Key Facts & Summary

  • Muscida is located at around 179 light-years / 55 parsecs away from the Sun.
  • It has an apparent visual magnitude of +3.35, and an absolute magnitude of -0.40.
  • Muscida is a yellowish type G4 II-III star, which places it between the giant and bright giant stages of its evolution.
  • This star is much bigger than our Sun, having 3.09 solar masses, and an enormous radius, 14 solar radii. Thus, Muscida should be around 30 times bigger than our Sun.
  • The star has a radial velocity of around +19.8 kilometers / +12.3 miles per second.
  • Muscida is 138 times brighter than our Sun.
  • The surface gravity on Muscida has been estimated at 2.64 cgs.
  • Muscida is cooler than our Sun, having surface average temperatures of around 5,242 K.
  • Muscida is also quite a young star, having only 360 million years since its formation.
  • The rotational velocity of Muscida is around 15 kilometers / 9.3 miles per second.
  • Some believe that this star is a variable type, yet observations continue to determine this.
  • Muscida is a member of the thin disk population, and it is following an orbit through the Milky Way galaxy with an eccentricity of 0.12. It comes as close to the galactic center as 23.5 kly / 7.2 kpc and as distant as 30.2 kly / 9.3 kpc.
  • Muscida is considered a runaway star due to its high peculiar velocity.
  • In 2012, an exoplanet was discovered orbiting around Muscida. It appears to be a gas giant around 4.1 times as massive as Jupiter.
  • The constellation of Ursa Major is among the oldest constellations.

Omicron Ursae Majoris is the star’s Bayer designation. The traditional name Muscida is also shared with the optical double star Pi Ursae Majoris.

In 2016, the IAU officially approved the name Muscida for the star. The name appears to be of Latin origin, and it translates to “muzzle”, which is fitting since the star marks the muzzle of the great celestial bear.

Apparently, the 17th-century German astronomer, Bayer, stated that the Arabs called this star Muscida, a word coined in the Middle Ages for the muzzle of an animal.

Formation

The star Muscida formed at roughly 360 million years ago, with a margin error of around more or less than 30 million years. Muscida formed out of an interstellar medium of dust and gas.

Gravity pulled the swirling gas and dust together and resulted in the star, Muscida. The exoplanet orbiting around Muscida also formed from this interstellar medium, and it is currently unknown if there may be more stars around Muscida.

Distance, Size, and Mass

Muscida is located at around 179 light-years / 55 parsecs away from Earth. It is bright enough to be seen with the naked eye under favorable conditions.

Muscida is a giant star and as such it is more bigger than the Sun, for example, Muscida has 3.09 solar masses, or 309% of the Sun’s mass, and a radius of around 14 solar radii, or 1,400% of the Sun’s radius. Thus, Muscida is more than likely around 30 times bigger than our Sun.

Other Characteristics

Omicron Ursae Majoris / Muscida, is a yellowish type G4 II-III star, which places it between the giant and bright giant stages of its evolution.

It has an apparent visual magnitude of +3.35, and an absolute magnitude of -0.40, being 138 times brighter than our Sun. Muscida has average surface temperatures of around 5,242 K, this means that it is cooler than our Sun.

The star has a radial velocity of around +19.8 kilometers / +12.3 miles per second. The surface gravity on Muscida has been estimated at 2.64 cgs.

The rotational velocity of Muscida is around 15 kilometers / 9.3 miles per second. Some believe that this star is a variable type, yet observations continue to determine this.

Muscida is also a member of the thin disk population, and it is following an orbit through the Milky Way galaxy with an eccentricity of 0.12. It comes as close to the galactic center as 23.5 kly / 7.2 kpc and as distant as 30.2 kly / 9.3 kpc.

Planetary System

In 2012, an extrasolar planet, designated as Omicron Ursae Majoris Ab, was discovered. It appears that this exoplanet is orbiting Muscida at a distance of 3.9 AU ( almost four times the distance between Earth and the Sun.)

The exoplanet is a gas giant which is 4.1 times more massive than Jupiter. It completes an orbit around Muscida, once every 1630 days. It is unknown if there are more planets around Muscida, but chances are high.

In regards to its other neighbors, Muscida has a magnitude 15.2 common proper motion companion at an angular separation of 7.1 arcseconds. 

The Muscida star system is a source of X-rays, and the probability that Muscida’s companion is the source of it, are high, around 99.4%. Muscida is sometimes listed with more companions, however, based on proper motion data, these appear to be merely optical companions.

Location

Muscida is located in the constellation of Ursa Major, the celestial great bear. Ursa Major is a constellation in the northern sky, whose associated mythology likely dates back into prehistory.

This constellation was among the 48 listed by the Greek astronomer Ptolemy, in his 2nd century Almagest. Today, Ursa Major is the third largest constellation among the 88 official modern constellations.

Ursa Major is known for the famous asterism, the Big Dipper, and also for the two stars Dubhe and Merak, which point towards the place of the current northern pole star, Polaris.

Ursa Major is visible throughout the year from most of the northern hemisphere, and appears circumpolar above the mid-northern latitudes. From southern latitudes, the main asterism is invisible, but other parts of the constellation can still be admired.

Muscida is situated close to the northern celestial pole, and thus it is visible for almost all year. One of the best months to observe stars and deep-sky objects in this constellation is during April.

The Future

Muscida prepares to become a brighter red giant. This is evident due to the speed of its evolution.

Did you know?

  • The Chinese know Muscida as Nei Jie yi – the First Star of Inner Steps – Inner Steps being a Chinese asterism formed by Ursae Majoris, 16 Ursae Majoris, 6 Ursae Majoris, 23 Ursae Majoris, 5 Ursae Majoris, and 17 Ursae Majoris. 
  • The constellation of Ursa Major has been depicted as a bear, usually female, by many distinct civilizations.
  • Muscida was also part of an Arabic asterism known as Al Thiba, which translates to the Gazelle.

Sources:

  1. Wikipedia
  2. Stars.astro.edu

Image sources: