Zeta Andromedae

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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[1] mas
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

Coordinates: Sky map 00h 47m 20.3254s, +24° 16′ 01.841″

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 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.[3] The orbital period of the binary is 17.77 days.

Location[edit]

This star's location in the constellation Andromeda can be seen in the following diagram:

Diagram of Andromeda constellation

Direct imaging[edit]

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[8]
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.[8] A Sun-like differential rotation of the star was observed instead.[3]

Visual companions[edit]

The WDS lists more than one visual companion to the eclipsing binary.[4] 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.[9]

Multiple/double star designation: WDS 00473+2416[10]
ComponentPrimaryRight
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[edit]

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.)[11]

Notes[edit]

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

References[edit]

  1. ^ a b c d e 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.
  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, 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. ^ 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.
  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.
  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. ^ 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.
  9. ^ 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.
  10. ^ 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.
  11. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日

External links[edit]