Zeta Andromedae

Not to be confused with Z Andromedae.
ζ Andromedae
Location of ζ Andromedae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Andromeda
Right ascension 00h 47m 20.32547s[1]
Declination +24° 16′ 01.8408″[1]
Apparent magnitude (V) 3.92 to 4.14[2]
Characteristics
Spectral type K1III + KV[3]
U−B color index +0.90[4]
B−V color index +1.12[4]
R−I color index +0.59[4]
Variable type ELL/RS[2]
Astrometry
Radial velocity (Rv)−24.43 ± 0.1[5] km/s
Proper motion (μ) RA: −101.17[1] mas/yr
Dec.: −81.77[1] mas/yr
Parallax (π)17.24 ± 0.26 mas[1]
Distance189 ± 3 ly
(58.0 ± 0.9 pc)
Absolute magnitude (MV)+0.14[3]
Orbit[3]
Period (P)17.769426
Semi-major axis (a)2.7 R*
Eccentricity (e)0.0
Inclination (i)65 ± 5°
Details
Aa
Mass2.6 ± 0.4[3] M☉
Radius15.9 ± 0.8[6] R☉
Luminosity95.5[3] L☉
Surface gravity (log g)2.8[3] cgs
Temperature4,665 ± 140[6] K
Metallicity [Fe/H]−0.30[3] dex
Rotation17.77 days[7]
Rotational velocity (v sin i)41.4 ± 0.2[3] km/s
Ab
Mass0.75[3] M☉
Other designations
ζ And, Zeta Andromedae, Zeta And, 34 Andromedae, 34 And, BD+23 106, CCDM J00473+2416A, FK5 27, GC 940, HD 4502, HIP 3693, HR 215, IDS 00421+2344 A, PPM 90149, SAO 74267, WDS 00473+2416A.
Database references
SIMBADdata

Zeta Andromedae (Zeta And, ζ Andromedae, ζ And) is a star system in the constellation Andromeda. It is approximately 189 light-years from Earth.

Zeta Andromedae is the star's Bayer designation. It also has the Flamsteed designation 34 Andromedae and multiple other designations in stellar catalogues.

Location

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Sidney Hall - Urania's Mirror - Gloria Frederici, Andromeda, and Triangula (north is to the left)

The star's location is in the northern constellation Andromeda, in which it is the second-most southerly of the stars in this often drawn characteristic shape representing the mythical princess asterism, after η Andromedae.

System

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A visual band light curve for Zeta Andromedae, adapted from Kővári et al. (2006)[8]

The system is a spectroscopic binary whose primary is classified as an orange K-type giant with a mean apparent magnitude of +4.08. Due to brightness changes caused by the ellipsoidal shape of that object, 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.[3] The orbital period of the binary is 17.77 days.

Direct imaging

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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.

Additional star parameters[9]
Parameter Value
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.[9] A Sun-like differential rotation of the star was observed instead.[3]

Visual companions

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The WDS notes three visual companions to the eclipsing binary (Aa and Ab, forming binary A).[4] The parallax of the D star has been measured by Gaia proving its distance to be much greater than Zeta Andromedae, probably a distant red giant.[10] The closest companion, B, is likewise a background object.[11] The companion C at 97″ shares a common proper motion and a similar parallax.[12]

Multiple/double star designation: WDS 00473+2416[13]
Component Primary Right
ascension (α)
Equinox J2000.0		 Declination (δ)
Equinox J2000.0		 Epoch of
observed
separation		 Angular
distance
from
primary		 Position
angle
(relative
to primary)		 Apparent
magnitude
(V)		 Database
reference
B A 00h 47m 20.2s+24° 16′ 33″ 1959 32.6″ 0° 15.3
C A 00h 47m 15.2s+24° 15′ 03″ 1997 97.0″ 231° 13.6
D A 00h 47m 09.0s+24° 15′ 33″ 2006 155.5″ 260° 10.80 SIMBAD

Naming

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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, the Chinese name for ζ Andromedae itself is 奎宿二 (Kuí Sù èr, English: the Second Star of Legs).[14]

Notes

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  1. ^ Azimuthal angle between the rotational axis and our line of sight
  2. ^ Longitudinal angle between the north pole and the East direction

References

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  1. ^ a b c d e Van Leeuwen, F. (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.
  2. ^ a b zet And, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars Archived 2017-06-20 at the Wayback Machine, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line August 29, 2008.
  3. ^ a b c d e f g h i j k 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.
  4. ^ a b c d 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.
  5. ^ Karataș, Yüksel; Bilir, Selçuk; Eker, Zeki; Demircan, Osman; Liebert, James; Hawley, Suzanne L.; Fraser, Oliver J.; Covey, Kevin R.; Lowrance, Patrick; Kirkpatrick, J. Davy; Burgasser, Adam J. (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): 1069–1092. arXiv:astro-ph/0404219. Bibcode:2004MNRAS.349.1069K. doi:10.1111/j.1365-2966.2004.07588.x. S2CID 15290475.
  6. ^ a b 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. S2CID 118683792.
  7. ^ 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
  8. ^ Kővári, Zsolt; Oláh, Katalin; Bartus, János; Strassmeier, Klaus G.; Granzer, Thomas (August 2006). "Spot Modelling of ζ Andromedae". Astrophysics and Space Science. 304 (1–4): 55–57. Bibcode:2006Ap&SS.304...55K. doi:10.1007/s10509-006-9073-4. S2CID 119574869. Retrieved 9 August 2022.
  9. ^ 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.
  10. ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  11. ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  12. ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  13. ^ 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.
  14. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日 Archived 2016-03-03 at the Wayback Machine
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