Mu Andromedae (Mu And, μ Andromedae, μ And) is the Bayer designation for a star in the northern constellation of Andromeda. It has an apparent visual magnitude of 3.87,[2] making it readily visible to the naked eye. Based upon parallax measurements, it is approximately 130 light-years (40 parsecs) from Earth.[1] In the constellation, the star is situated about halfway between the bright star Mirach to the southwest and the Andromeda Galaxy (M31) to the northeast.[11]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h 56m 45.21211s[1] |
| Declination | +38° 29′ 57.6380″[1] |
| Apparent magnitude (V) | 3.87[2] |
| Characteristics | |
| Spectral type | A5 V[3] |
| U−B color index | +0.15[2] |
| B−V color index | +0.12[2] |
| Astrometry | |
| Radial velocity (Rv) | +7.6[4] km/s |
| Proper motion (μ) | RA: +153.48[1] mas/yr Dec.: +36.49[1] mas/yr |
| Parallax (π) | 25.14 ± 0.86 mas[1] |
| Distance | 130 ± 4 ly (40 ± 1 pc) |
| Absolute magnitude (MV) | +0.86[5] |
| Orbit[6] | |
| Period (P) | 550.7 ± 0.2 d |
| Semi-major axis (a) | 46.66 ± 0.06 mas |
| Eccentricity (e) | 0.8405 ± 0.0009 |
| Inclination (i) | 52.5 ± 0.3° |
| Longitude of the node (Ω) | −17.6 ± 0.2° |
| Periastron epoch (T) | 55765.45 ± 0.04 MJD |
| Argument of periastron (ω) (secondary) | 168.9 ± 0.3° |
| Semi-amplitude (K1) (primary) | 11.1 ± 0.5 km/s |
| Details | |
| Mass | 2.0[7] M☉ |
| Radius | 2.4[7] R☉ |
| Luminosity | 21[7] L☉ |
| Surface gravity (log g) | 3.99[7] cgs |
| Temperature | 7,959[8] K |
| Metallicity [Fe/H] | +0.03[8] dex |
| Rotational velocity (v sin i) | 75[9] km/s |
| Age | 600[10] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The spectrum of this star matches a stellar classification of A5 V,[3] indicating that it is an A-type main sequence star. It has double the mass of the Sun and 2.4 times the Sun's radius.[7] The star is radiating about 21[7] times the luminosity of the Sun from its outer envelope at an effective temperature of 7,959 K,[8] giving it the characteristic white glow of an A-type star.[12] It is estimated to be about 600 million years old,[10] with a relatively high projected rotational velocity of 75 km/s.[9] Mu Andromedae has recently been found to be a binary system. The two stars orbit each other every 550.7 days.[6]
Naming edit
In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of μ Andromedae, η Andromedae, 65 Piscium, ζ Andromedae, ε Andromedae, δ Andromedae, π Andromedae, ν Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ¹ Piscium. Consequently, the Chinese name for μ Andromedae itself is 奎宿八 (Kuí Sù bā, English: the Eighth Star of Legs.)[13]
References edit
- ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
- ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
- ^ Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institute of Washington D.C., Bibcode:1953GCRV..C......0W.
- ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
- ^ a b Roettenbacher, R.M.; Monnier, J.D.; Korhonen, H.; Aarnio, A.N.; Baron, F.; Che, X.; Harmon, R.O.; Kővári, Zs.; Kraus, S.; Schaefer, G.H.; Torres, G.; Zhao, M.; Ten Brummelaar, T.A.; Sturmann, J.; Sturmann, L. (2016). "No Sun-like dynamo on the active star ζ Andromedae from starspot asymmetry". Nature. 533 (7602): 217–220. arXiv:1709.10107. Bibcode:2016Natur.533..217R. doi:10.1038/nature17444. PMID 27144357. S2CID 4466687.
- ^ a b c d e f Malagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series, 85 (3): 1015–1019, Bibcode:1990A&AS...85.1015M.
- ^ a b c Gardiner, R. B.; Kupka, F.; Smalley, B. (July 1999), "Testing convection theories using Balmer line profiles of A, F, and G stars", Astronomy and Astrophysics, 347: 876–890, Bibcode:1999A&A...347..876G.
- ^ a b Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298.
- ^ a b Rieke, G. H.; et al. (February 2005), "Decay of Planetary Debris Disks", The Astrophysical Journal, 620 (2): 1010–1026, Bibcode:2005ApJ...620.1010R, CiteSeerX 10.1.1.579.8956, doi:10.1086/426937, S2CID 54676993.
- ^ Reddy, Francis (2011), Celestial Delights: The Best Astronomical Events Through 2020 (3rd ed.), Springer, p. 236, ISBN 978-1461406099.
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 18, 2012, retrieved 2012-01-16.
- ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日