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[7] | |
| Mass | 2.21±0.09 M☉ |
| Radius | 3.03±0.11 R☉ |
| Luminosity | 40±3 L☉ |
| Surface gravity (log g) | 3.99[8] cgs |
| Temperature | 8,320±150 K |
| Metallicity [Fe/H] | +0.03[9] dex |
| Rotational velocity (v sin i) | 75[10] km/s |
| Age | 724±21 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 2.2 times the mass of the Sun and three times the Sun's radius. The star is radiating about 4p times the luminosity of the Sun from its outer envelope at an effective temperature of 8,320 K,[7] giving it the characteristic white glow of an A-type star.[12] It is estimated to be about 724 million years old,[7] with a relatively high projected rotational velocity of 75 km/s.[10] Mu Andromedae has recently been found to be a binary system. The two stars orbit each other every 550.7 days.[6]
Naming
editIn 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 Maestro, V.; Che, X.; Huber, D.; Ireland, M. J.; Monnier, J. D.; White, T. R.; Kok, Y.; Robertson, J. G.; Schaefer, G. H.; Brummelaar, T. A. T.; Tuthill, P. G. (2013). "Optical interferometry of early-type stars with PAVO@CHARA - I. Fundamental stellar properties". Monthly Notices of the Royal Astronomical Society. 434 (2): 1321. arXiv:1306.5937. Bibcode:2013MNRAS.434.1321M. doi:10.1093/mnras/stt1092. S2CID 2361434.
- ^ 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.
- ^ 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.
- ^ 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