Mu Ursae Majoris
 Location of μ Ursae Majoris (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Ursa Major |
| Right ascension | 10h 22m 19.744s[1] |
| Declination | +41° 29′ 58.28″[1] |
| Apparent magnitude (V) | +3.06[2] |
| Characteristics | |
| Spectral type | M0 IIIab[2] |
| U−B color index | +1.90[3] |
| B−V color index | +1.59[3] |
| Astrometry | |
| Radial velocity (Rv) | –21.30 ± 1.66[4] km/s |
| Proper motion (μ) | RA: –81.47[5] mas/yr Dec.: +35.34[5] mas/yr |
| Parallax (π) | 14.16 ± 0.54[5] mas |
| Distance | 230 ± 9 ly (71 ± 3 pc) |
| Orbit[6] | |
| Period (P) | 230.089 ± 0.039 days |
| Eccentricity (e) | 0.061 ± 0.022 |
| Periastron epoch (T) | 2425577.03 JD |
| Argument of periastron (ω) (secondary) |
236.4 ± 17.4° |
| Semi-amplitude (K1) (primary) |
7.43 ± 0.16 km/s |
| Details | |
| Radius | 75[7] R☉ |
| Luminosity | 977[7]–1,200[4] L☉ |
| Surface gravity (log g) | 1.0[4] cgs |
| Temperature | 3,899[4] K |
| Metallicity [Fe/H] | +0.00[8] dex |
| Rotational velocity (v sin i) | 7.5[4] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Mu Ursae Majoris (Mu UMa, μ Ursae Majoris, μ UMa) is a star in the constellation 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 Earth, with a margin of error of 4%.[5] This star has the proper name Tania Australis (formerly Tania australis[10])
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[7] times the radius of the Sun whilst the outer atmosphere has cooled to an effective temperature of 3,899 K,[4] giving it the orange-red hued glow of an M-type star.[11] Estimates of the luminosity range from 977[7]–1,200[4] times that of the Sun. It is classified as a semiregular variable star and its brightness varies from magnitude 2.99m to 3.33m.
This is a spectroscopic binary star system with a companion a mere 1.5[citation needed] AU from the primary with an orbital period of 230 days.[6]
Name and etymology
- The traditional name Tania' (share with λ UMa) comes from the Arabic phrase Al Fiḳrah al Thānia "the Second Spring (of the Gazelle)".[12] The term Australis meaning "the south side" in Latin.
- In Chinese, 三台 (Sān Tái), meaning Three Steps, refers to an asterism consisting of μ Ursae Majoris, ι Ursae Majoris, κ Ursae Majoris, λ Ursae Majoris, ν Ursae Majoris and ξ Ursae Majoris. Consequently, μ Ursae Majoris itself is known as 三台四 (Sān Tái sì, English: the Fourth Star of Three Steps) and 中台二 (Zhōng Tái èr, English: Star of Second Middle Step).[13]
References
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- ↑ 5.0 5.1 5.2 5.3 Lua error in package.lua at line 80: module 'strict' not found. Note: see VizieR catalogue I/311.
- ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 7.0 7.1 7.2 7.3 Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ Richard Hinckley Allen :Star Names — Their Lore and Meaning - Ursa Major, the Greater Bear
- ↑ (Chinese) (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 21 日
