Astronomy:Mu Andromedae

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Short description: Binary star in the constellation Andromeda
μ Andromedae
Location of μ Andromedae (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Andromeda
Right ascension  00h 56m 45.209s[1]
Declination +38° 29′ 57.60″[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]
Variable type RS CVn[4]
Astrometry
Radial velocity (Rv)+7.6[5] km/s
Proper motion (μ) RA: +151.021[1] mas/yr
Dec.: +34.800[1] mas/yr
Parallax (π)26.7046 ± 0.6467[1] mas
Distance122 ± 3 ly
(37.4 ± 0.9 pc)
Absolute magnitude (MV)+0.86[6]
Orbit[4]
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]
Mass2.21±0.09 M☉
Radius3.03±0.11 R☉
Luminosity40±3 L☉
Surface gravity (log g)3.99[8] cgs
Temperature8,320±150 K
Metallicity [Fe/H]+0.03[9] dex
Rotational velocity (v sin i)75[10] km/s
Age724±21 Myr
Other designations
μ Andromedae, μ And, Mu And, 37 Andromedae, BD+37°175, FK5 33, HD 5448, HIP 4436, HR 269, SAO 54281, PPM 65785[11]
Database references
SIMBADdata

Mu Andromedae is a binary star system in the northern constellation of Andromeda. Its Bayer designation is Latinized from μ Andromedae, and abbreviated Mu And or μ And, respectively. The system has an apparent visual magnitude of 3.87,[2] making it readily visible to the naked eye. Based upon parallax measurements, it is located at a distance of approximately 122 light-years (37 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.[12]

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 40 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.[13] It is estimated to be about 724 million years old,[7] with a relatively high projected rotational velocity of 75 km/s.[10]

In 2007, Mu Andromedae was found to be a tidally-locked close binary system with an unseen companion. The two stars orbit each other every 550.7 days. The tidal interactions have spun up the primary star, causing it to become magnetically active and host unusually strong starspots.[4]

Naming

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.)[14]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 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. 
  3. ↑ 3.0 3.1 Cowley, A. et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal 74: 375–406, doi:10.1086/110819, Bibcode: 1969AJ.....74..375C. 
  4. ↑ 4.0 4.1 4.2 Roettenbacher, R. M. et al. (2016), "No Sun-like dynamo on the active star ζ Andromedae from starspot asymmetry", Nature 533 (7602): 217–220, doi:10.1038/nature17444, PMID 27144357, Bibcode: 2016Natur.533..217R. 
  5. ↑ 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. 
  6. ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 7.2 Maestro, V. et al. (2013), "Optical interferometry of early-type stars with PAVO@CHARA - I. Fundamental stellar properties", Monthly Notices of the Royal Astronomical Society 434 (2): 1321, doi:10.1093/mnras/stt1092, Bibcode: 2013MNRAS.434.1321M. 
  8. ↑ 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. 
  9. ↑ 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. 
  10. ↑ 10.0 10.1 Royer, F. et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics 463 (2): 671–682, doi:10.1051/0004-6361:20065224, Bibcode: 2007A&A...463..671R. 
  11. ↑ "mu. And". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=mu.+And. 
  12. ↑ Reddy, Francis (2011), Celestial Delights: The Best Astronomical Events Through 2020 (3rd ed.), Springer, p. 236, ISBN 978-1461406099, https://books.google.com/books?id=OcGsCZPlDIoC&pg=PA236. 
  13. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16. 
  14. ↑ Script error: The function "in_lang" does not exist. AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日



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