Mu Ursae Majoris

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Mu Ursae Majoris
Ursa Major IAU.svg
Cercle rouge 100%25.svg

Location of μ Ursae Majoris (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Ursa Major
Right ascension 10h 22m 19.73976s [1]
Declination +41° 29 58.2691 [1]
Apparent magnitude  (V)+3.06 [2]
Characteristics
Evolutionary stage asymptotic giant branch [3]
Spectral type M0 IIIab [2]
U−B color index +1.90 [4]
B−V color index +1.59 [4]
Variable type suspected [5]
Astrometry
Radial velocity (Rv)–21.30 ± 1.66 [6]  km/s
Proper motion (μ)RA: –81.47 [1]   mas/yr
Dec.: +35.34 [1]   mas/yr
Parallax (π)17.7987 ± 0.3933 [7]   mas
Distance 183 ± 4  ly
(56 ± 1  pc)
Absolute magnitude  (MV)−1.11±0.083 [8]
Orbit [9]
Period (P)230.089 days
Semi-major axis (a).0028″
Eccentricity (e)0.061
Inclination (i)13.6°
Periastron epoch (T)2425577.030 JD
Argument of periastron (ω)
(secondary)
236.4°
Semi-amplitude (K1)
(primary)
7.40 km/s
Details
Radius 75 [10]   R
Luminosity 977 [10] –1,200 [6]   L
Surface gravity (log g)1.0 [6]   cgs
Temperature 3,899 [6]   K
Metallicity [Fe/H]+0.00 [11]   dex
Rotational velocity (v sin i)7.5 [6]  km/s
Other designations
Tania Australis, Alkafzah al Thaniyah, μ Ursae Majoris, μ UMa, Mu UMa, 34 Ursae Majoris, BD+42 2115, FK5  386, GC  14232, HD  89758, HIP  50801, HR  4069, PPM  51850, SAO  43310
Database references
SIMBAD data

Mu Ursae Majoris (μ Ursae Majoris, abbreviated Mu UMa, μ UMa), formally named Tania Australis /ˈtniəɔːˈstrlɪs/ , [12] [13] is a binary star in the constellation of Ursa Major. An apparent visual magnitude of +3.06 [2] places it among the brighter members of the constellation. Parallax measurements give an estimated distance of roughly 230 light-years (71 parsecs ) from the Sun, with a margin of error of 4%. [1]

Contents

Stellar system

Mu Ursae Majoris is an evolved star that is currently in the red giant stage with a stellar classification of M0 IIIab. [2] It has expanded to 75 [10] times the radius of the Sun whilst the outer atmosphere has cooled to an effective temperature of 3,899 K, [6] giving it the orange-red hued glow of an M-type star. [14] Estimates of the luminosity range from 977 [10] –1,200 [6] times that of the Sun. It is classified as a suspected variable star with a brightness variation from magnitude 2.99m to 3.33m. [5]

This is a spectroscopic binary star system with a companion a mere 0.2 AU from the primary, assuming a distance of 71 parsecs, with an orbital period of 230 days. [9]

Nomenclature

μ Ursae Majoris (Latinised to Mu Ursae Majoris) is the star's Bayer designation.

It bore the traditional names Tania (shared with Lambda Ursae Majoris) and Tania Australis. Tania comes from the Arabic phrase Al Fiḳrah al Thānia 'the Second Spring (of the Gazelle)'. [15] and Australis (originally australis [16] ) is Latin for 'the south side'. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) [17] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 [18] included a table of the first two batches of names approved by the WGSN; which included Tania Australis for this star.

In Chinese, 三台 (Sān Tái), meaning Three Steps , refers to an asterism consisting of Mu Ursae Majoris, Iota Ursae Majoris, Kappa Ursae Majoris, Lambda Ursae Majoris, Nu Ursae Majoris and Xi Ursae Majoris. Consequently, the Chinese name for Mu Ursae Majoris itself is 中台二 (Zhōng Tái èr, English: Star of Second Middle Step). [19]

Related Research Articles

Epsilon Ursae Majoris Star in the constellation Ursa Major

Epsilon Ursae Majoris, officially named Alioth, is, despite being designated "ε" (epsilon), the brightest star in the constellation of Ursa Major, and at magnitude 1.77 is the thirty-third brightest star in the sky.

Alpha Ursae Majoris Binary star in the constellation Ursa Major

Alpha Ursae Majoris, formally named Dubhe, is, despite being designated "α" (alpha), the second-brightest object in the constellation of Ursa Major.

Mizar Sextuple star system in the constellation Ursa Major

Mizar is a second-magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris. It forms a well-known naked eye double star with the fainter star Alcor, and is itself a quadruple star system. The whole system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group.

Iota Ursae Majoris Double binary star system in the constellation Ursa Major

Iota Ursae Majoris, also named Talitha, is a star system in the northern circumpolar constellation of Ursa Major. It has an apparent visual magnitude of 3.14, making it visible to the naked eye and placing it among the brighter members of this constellation. Based upon parallax measurements, it is located at a distance of 47.3 light-years from the Sun.

Omicron Ursae Majoris Star in the constellation Ursa Major

Omicron Ursae Majoris, formally named Muscida, is a star system in the northern circumpolar constellation of Ursa Major. It has an apparent visual magnitude of +3.35 and is located at a distance of around 179 light-years from the Sun. In 2012, an extrasolar planet, designated Omicron Ursae Majoris Ab was found to be orbiting the primary.

Lambda Ursae Majoris Star in the constellation Ursa Major

Lambda Ursae Majoris, formally named Tania Borealis, is a star in the northern circumpolar constellation of Ursa Major.

Nu Ursae Majoris Star in the constellation Ursa Major

Nu Ursae Majoris, formally named Alula Borealis, is a double star in the northern circumpolar constellation of Ursa Major. At an apparent visual magnitude of +3.490, it is bright enough to be seen with the naked eye. Based upon parallax measurements, the distance to ν Ursae Majoris is about 399 light-years.

Kappa Ursae Majoris Star in the constellation Ursa Major

Kappa Ursae Majoris is a binary star in the constellation of Ursa Major. With a combined apparent magnitude of +3.60, the system is approximately 358 light-years from Earth.

Xi Ursae Majoris Star in the constellation Ursa Major

Xi Ursae Majoris, also named Alula Australis, is a star system in the constellation of Ursa Major. On May 2, 1780, Sir William Herschel discovered that this was a binary star system, making it the first such system ever discovered. It was the first visual double star for which an orbit was calculated, when it was computed by Félix Savary in 1828. It is also a variable star with a small amplitude. Xi Ursae Majoris is found in the left hind paw of the Great Bear.

Omega Ursae Majoris Binary system in the constellation Ursa Major

Omega Ursae Majoris is the Bayer designation for a binary star system in the northern circumpolar constellation of Ursa Major. It is visible to the naked eye with an apparent visual magnitude of 4.61. Based upon an annual parallax shift of 13.24 mas, it is roughly 246 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.11 due to interstellar dust.

Pi1 Ursae Minoris is a common proper motion binary star system in the northern circumpolar constellation of Ursa Minor. The pair have apparent visual magnitudes of +6.58 and +7.31, with a combined magnitude of 6.1. They are located about 71 light years from the Sun. The two have an angular separation of 31.4 arc seconds, which corresponds to a physical separation of about 680 AU, and orbit each other with a period of about 13,100 years.

Phi Aquarii Star in the constellation Aquarius

Phi Aquarii, Latinized from φ Aquarii, is the Bayer designation for a binary star system in the equatorial constellation of Aquarius. It is visible to the naked eye with a combined apparent visual magnitude of +4.223. Parallax measurements indicate its distance from Earth is roughly 222 light-years, and it is drifting further away with a radial velocity of +2.5 km/s. It is 1.05 degrees south of the ecliptic so it is subject to lunar occultations.

Epsilon Aquilae Binary star in the constellation of Aquila

Epsilon Aquilae, Latinized from ε Aquilae, is the Bayer designation for a binary star system in the equatorial constellation of Aquila, near the western constellation boundary with Hercules. It has an apparent visual magnitude of 4.02 and is visible to the naked eye. Based upon an annual parallax of 23.993 mas, Epsilon Aquilae lies at a distance of approximately 136 light-years from Earth, but is drifting closer with a radial velocity of –46 km/s.

94 Aquarii is a triple star system in the equatorial constellation of Aquarius. 94 Aquarii is the Flamsteed designation. The brightest member has an apparent visual magnitude of 5.19, making it visible to the naked eye. The parallax measured by the Gaia spacecraft yields a distance estimate of around 73 light-years from Earth.

27 Arietis is a binary star system in the northern constellation of Aries. 27 Arietis is the Flamsteed designation. It is a dim, yellow-hued star that is close to the lower limit of what can be viewed with the naked eye, having an apparent visual magnitude is 6.21. The annual parallax shift of 11.64±0.12 mas corresponds to a physical distance of approximately 280 light-years from Earth. It is advancing closer to the Earth with a heliocentric radial velocity of −122.7 km/s, and may come as close as 84 light-years in around 643,000 years.

Xi Cancri is a spectroscopic binary star system in the zodiac constellation of Cancer. It is visible to the naked eye with an apparent visual magnitude of +5.15. Based upon parallax measurements obtained during the Hipparcos mission, it is roughly 370 light-years distant from the Sun.

Nu1 Canis Majoris1 Canis Majoris) is a binary star in the constellation Canis Major. It is visible to the naked eye with a combined apparent visual magnitude of 5.7. Based on parallax shift of 12.366 mas as seen from our orbit, this system is approximately 264 light years from the Sun.

S Antliae is a W Ursae Majoris-type eclipsing binary star in Antlia.

RR Ursae Minoris, abbreviated RR UMi, is a binary star system in the northern circumpolar constellation of Ursa Minor. It can be viewed with the naked eye, typically having an apparent visual magnitude of around 4.710. Based upon an annual parallax shift of 10.0 mas as seen from Earth's orbit, it is located 330 light years away. The system is moving further from the Sun with a heliocentric radial velocity of +6 km/s.

AE Phoenicis is a variable star in the constellation of Phoenix. An eclipsing binary, its apparent magnitude has a maximum of 7.56, dimming to 8.25 during primary eclipse and 8.19 during secondary eclipse. From parallax measurements by the Gaia spacecraft, the system is located at a distance of 168 light-years from Earth.

References

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