Epoch J2000.0 Equinox J2000.0 (ICRS)
|Right ascension||00h 47m 20.32547s|
|Declination||+24° 16′ 01.8408″|
|Apparent magnitude (V)||3.92 to 4.14|
|Spectral type||K1III + KV|
|U−B color index||+0.90|
|B−V color index||+1.12|
|R−I color index||+0.59|
|Radial velocity (Rv)||−24.43 ± 0.1 km/s|
|Proper motion (μ)|| RA: −101.17 mas/yr |
Dec.: −81.77 mas/yr
|Parallax (π)||17.24 ± 0.26 mas|
|Distance||189 ± 3 ly |
(58.0 ± 0.9 pc)
|Absolute magnitude (MV)||+0.14|
|Semi-major axis (a)||2.7 R*|
|Inclination (i)||65 ± 5°|
|Mass||2.6 ± 0.4 M☉|
|Radius||15.9 ± 0.8 R☉|
|Surface gravity (log g)||2.8 cgs|
|Temperature||4,665 ± 140 K|
|Metallicity [Fe/H]||−0.30 dex|
|Rotational velocity (v sin i)||41.4 ± 0.2 km/s|
Zeta Andromedae is a spectroscopic binary whose primary is classified as an orange K-type giant with a mean apparent magnitude of +4.08. In addition to brightness variation due to the ellipsoidal shape of the giant primary star, the system is also an RS Canum Venaticorum type variable star. Its brightness varies from magnitude +3.92 to +4.14 with a period of 17.77 days, and its spectrum shows strong and variable Ca II H and K lines. The orbital period of the binary is 17.77 days.
This star's location in the constellation Andromeda can be seen in the following diagram:
The primary component of this binary system, Zeta Andromedae Aa, is one of the few stars who has been imaged directly using Doppler imaging and long-baseline infrared interferometry. With direct imaging we can recover additional information about this star.
|Oblateness||1.060 ± 0.011|
|Polar radius||15.0 ± 0.8 R☉|
|Axis Inclination[a]||70.0 ± 2.8 °|
|Pole angle[b]||126 ± 1.9 °|
Direct imaging also allowed observation of starspots, (the analogue to sunspots), on this star, and their asymmetric distribution showed that the magnetic field of the star is generated by a mechanism different from the solar dynamo. A Sun-like differential rotation of the star was observed instead.
The WDS lists more than one visual companion to the eclipsing binary. B has common proper motion with A. C is probably only a line-of-sight companion that has no physical association. The parallax of the D component has been measured by Gaia and the distance of this star is much different.
In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of ζ Andromedae, η Andromedae, 65 Piscium, ε Andromedae, δ Andromedae, π Andromedae, ν Andromedae, μ Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ¹ Piscium. Consequently, ζ Andromedae itself is known as 奎宿二 (Kuí Sù èr, English: the Second Star of Legs.)
- Azimutal angle between the rotational axis and our line of sight
- Longitudinal angle between the north pole and the East direction
- Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- zet And, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line August 29, 2008.
- Kővári, Zs.; Bartus, J.; Strassmeier, K. G.; Oláh, K.; Weber, M.; Rice, J. B.; Washuettl, A. (2007). "Doppler imaging of stellar surface structure. XXIII. The ellipsoidal K giant binary ζ Andromedae". Astronomy and Astrophysics. 463 (3): 1071. Bibcode:2007A&A...463.1071K. doi:10.1051/0004-6361:20065982.
- HR 215, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line August 29, 2008.
- Karataş, Y.; Bilir, S.; Eker, Z.; Demircan, O. (2004). "Kinematics of chromospherically active binaries and evidence of an orbital period decrease in binary evolution". Monthly Notices of the Royal Astronomical Society. 349 (3): 1069. arXiv:astro-ph/0404219. Bibcode:2004MNRAS.349.1069K. doi:10.1111/j.1365-2966.2004.07588.x.
- Korhonen, H.; Wittkowski, M.; Kovári, Zs.; Granzer, Th.; Hackman, T.; Strassmeier, K. G. (2010). "Ellipsoidal primary of the RS CVn binary ζ Andromedae . Investigation using high-resolution spectroscopy and optical interferometry". Astronomy and Astrophysics. 515: A14. arXiv:1002.4201. Bibcode:2010A&A...515A..14K. doi:10.1051/0004-6361/200913736.
- Strassmeier, Klaus G. (September 2009), "Starspots", The Astronomy and Astrophysics Review, 17 (3): 251–308, Bibcode:2009A&ARv..17..251S, doi:10.1007/s00159-009-0020-6
- 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.
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- Entry 00473+2416, The Washington Double Star Catalog Archived April 12, 2008, at the Wayback Machine., United States Naval Observatory. Accessed on line August 29, 2008.
- (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日
- Zeta Andromedae at Alcyone Software's Star Data Pages
- Image ζ Andromedae
- Rachael Roettenbacher, "How the face of a distant star reveals our place in the cosmos," Aeon Magazine [retrieved July 27, 2016]