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Eta Andromedae

January 10, 2023

Eta Andromedae (Eta And, η Andromedae, η And) is a spectroscopic binary star in the constellation of Andromeda. It consists of two G-type subgiant or giant stars orbiting each other with a period of 115.7 days and has an overall apparent visual magnitude of approximately 4.403.[1][2]

η Andromedae
Location of η Andromedae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Andromeda
Right ascension 00h 57m 12.4000s[1]
Declination +23° 25′ 03.533″[1]
Apparent magnitude (V) 4.403[1]
Characteristics
Spectral type G8III-IV + G8III-IV[2]
U−B color index +0.69[3]
B−V color index +0.94[3]
R−I color index +0.48[3]
Astrometry
η And A
Radial velocity (Rv)−10.3 ± 0.9[1] km/s
Proper motion (μ) RA: −43.72[1] mas/yr
Dec.: −46.06[1] mas/yr
Parallax (π)13.44 ± 0.75 mas[1]
Distance240 ± 10 ly
(74 ± 4 pc)
Absolute magnitude (MV)0.52 ± 0.06[2]
η And B
Absolute magnitude (MV)1.07 ± 0.07[2]
Orbit[2]
Period (P)115.72 ± 0.01 d
Semi-major axis (a)10.37 ± 0.03 mas
Eccentricity (e)0.006 ± 0.002
Inclination (i)30.5 ± 0.4°
Longitude of the node (Ω)69.4 ± 0.5°
Periastron epoch (T)48013 ± 1 MJD
Argument of periastron (ω)
(secondary)		215 ± 4°
Details
η And A
Mass2.6 ± 0.35[4] M☉
Luminosity (bolometric)65 ± 3[2] L☉
Surface gravity (log g)2.8[2] cgs
Temperature4900[2] K
Age800 Million years
η And B
Mass2.3 ± 0.31[4] M☉
Luminosity (bolometric)39 ± 3[2] L☉
Surface gravity (log g)3.0[2] cgs
Temperature4900[2] K
Other designations
η Andromedae, η And, Eta And, 38 Andromedae, 38 And, MKT 2, FOX 116A, BD+22°153, CCDM J00572+2325A, FK5 2060, GC 1136, HD 5516, HIP 4463, HR 271, IDS 00519+2253 A, PPM 90327, SAO 74388, WDS 00572+2325A/Aa.[1][5][6]
Database references
SIMBADdata

History

 
η Andromedae system as seen from earth orbit, M 33 in background

Eta Andromedae was discovered to be a double-lined spectroscopic binary in a series of spectra taken in 1899 and 1900.[7] Its orbit was computed in 1946 from spectroscopic observations.[8] Because spectroscopy only reveals the radial velocity of a star towards or away from the viewer, such a computation does not determine all orbital elements. In observations made from 1990 to 1992, Eta Andromedae was resolved interferometrically by the Mark III Stellar Interferometer at Mount Wilson Observatory, California, United States. This allowed a more complete orbit to be computed and, in 1993, published.[2]

Naming

In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of η Andromedae, 65 Piscium, ζ Andromedae, 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 η Andromedae itself is 奎宿一 (Kuí Sù yī, English: the First Star of Legs.)[9]

Visual companion

Eta Andromedae has a visual companion star of apparent visual magnitude 11.5, BD+22°153B, visible 129.2 arcseconds away.[6]

References

  1. ^ a b c d e f g h i "* eta And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved August 23, 2008.
  2. ^ a b c d e f g h i j k l The spectroscopic binary eta Andromedae: Determination of the orbit by optical interferometry, C. A. Hummel et al., Astronomical Journal 106, #6 (December 1993), pp. 2486–2492, Bibcode:1993AJ....106.2486H, doi:10.1086/116816.
  3. ^ a b c HR 271, 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 23, 2008.
  4. ^ a b Table 2, Resolved double-lined spectroscopic binaries: A neglected source of hypothesis-free parallaxes and stellar masses, D. Pourbaix, Astronomy and Astrophysics Supplement 145 (August 2000), pp. 215–222, Bibcode:2000A&AS..145..215P.
  5. ^ Entry 00572+2325, discoverer code MKT 2, components Aa, The Washington Double Star Catalog April 12, 2008, at the Wayback Machine, United States Naval Observatory. Accessed on line August 27, 2008.
  6. ^ a b Entry 00572+2325, discoverer code FOX 116, components AB, The Washington Double Star Catalog April 12, 2008, at the Wayback Machine, United States Naval Observatory. Accessed on line August 23, 2008.
  7. ^ A list of nine stars whose velocities in the line of sight are variable, W. W. Campbell and W. H. Wright, Astrophysical Journal 12 (November 1900), pp. 254–257, Bibcode:1900ApJ....12..254C, doi:10.1086/140765.
  8. ^ The Spectroscopic Binary η Andromedae, Katherine C. Gordon, Astrophysical Journal 103 (January 1946), pp. 13–15, Bibcode:1946ApJ...103...13G.
  9. ^ (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

  • Image η Andromedae


January 10, 2023
andromedae, andromedae, spectroscopic, binary, star, constellation, andromeda, consists, type, subgiant, giant, stars, orbiting, each, other, with, period, days, overall, apparent, visual, magnitude, approximately, andromedaelocation, andromedae, circled, obse. Eta Andromedae Eta And h Andromedae h And is a spectroscopic binary star in the constellation of Andromeda It consists of two G type subgiant or giant stars orbiting each other with a period of 115 7 days and has an overall apparent visual magnitude of approximately 4 403 1 2 h AndromedaeLocation of h Andromedae circled Observation dataEpoch J2000 0 Equinox J2000 0 ICRS Constellation AndromedaRight ascension 00h 57m 12 4000s 1 Declination 23 25 03 533 1 Apparent magnitude V 4 403 1 CharacteristicsSpectral type G8III IV G8III IV 2 U B color index 0 69 3 B V color index 0 94 3 R I color index 0 48 3 Astrometryh And ARadial velocity Rv 10 3 0 9 1 km sProper motion m RA 43 72 1 mas yr Dec 46 06 1 mas yrParallax p 13 44 0 75 mas 1 Distance240 10 ly 74 4 pc Absolute magnitude MV 0 52 0 06 2 h And BAbsolute magnitude MV 1 07 0 07 2 Orbit 2 Period P 115 72 0 01 dSemi major axis a 10 37 0 03 masEccentricity e 0 006 0 002Inclination i 30 5 0 4 Longitude of the node W 69 4 0 5 Periastron epoch T 48013 1 MJDArgument of periastron w secondary 215 4 Detailsh And AMass2 6 0 35 4 M Luminosity bolometric 65 3 2 L Surface gravity log g 2 8 2 cgsTemperature4900 2 KAge800 Million yearsh And BMass2 3 0 31 4 M Luminosity bolometric 39 3 2 L Surface gravity log g 3 0 2 cgsTemperature4900 2 KOther designationsh Andromedae h And Eta And 38 Andromedae 38 And MKT 2 FOX 116A BD 22 153 CCDM J00572 2325A FK5 2060 GC 1136 HD 5516 HIP 4463 HR 271 IDS 00519 2253 A PPM 90327 SAO 74388 WDS 00572 2325A Aa 1 5 6 Database referencesSIMBADdata Contents 1 History 2 Naming 3 Visual companion 4 References 5 External linksHistory Edit h Andromedae system as seen from earth orbit M 33 in background Eta Andromedae was discovered to be a double lined spectroscopic binary in a series of spectra taken in 1899 and 1900 7 Its orbit was computed in 1946 from spectroscopic observations 8 Because spectroscopy only reveals the radial velocity of a star towards or away from the viewer such a computation does not determine all orbital elements In observations made from 1990 to 1992 Eta Andromedae was resolved interferometrically by the Mark III Stellar Interferometer at Mount Wilson Observatory California United States This allowed a more complete orbit to be computed and in 1993 published 2 Naming EditIn Chinese 奎宿 Kui Su meaning Legs asterism refers to an asterism consisting of h Andromedae 65 Piscium z Andromedae e Andromedae d Andromedae p Andromedae n Andromedae m Andromedae b Andromedae s Piscium t Piscium 91 Piscium y Piscium f Piscium x Piscium and ps Piscium Consequently the Chinese name for h Andromedae itself is 奎宿一 Kui Su yi English the First Star of Legs 9 Visual companion EditEta Andromedae has a visual companion star of apparent visual magnitude 11 5 BD 22 153B visible 129 2 arcseconds away 6 References Edit a b c d e f g h i eta And SIMBAD Centre de donnees astronomiques de Strasbourg Retrieved August 23 2008 a b c d e f g h i j k l The spectroscopic binary eta Andromedae Determination of the orbit by optical interferometry C A Hummel et al Astronomical Journal 106 6 December 1993 pp 2486 2492 Bibcode 1993AJ 106 2486H doi 10 1086 116816 a b c HR 271 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 23 2008 a b Table 2 Resolved double lined spectroscopic binaries A neglected source of hypothesis free parallaxes and stellar masses D Pourbaix Astronomy and Astrophysics Supplement 145 August 2000 pp 215 222 Bibcode 2000A amp AS 145 215P Entry 00572 2325 discoverer code MKT 2 components Aa The Washington Double Star Catalog Archived April 12 2008 at the Wayback Machine United States Naval Observatory Accessed on line August 27 2008 a b Entry 00572 2325 discoverer code FOX 116 components AB The Washington Double Star Catalog Archived April 12 2008 at the Wayback Machine United States Naval Observatory Accessed on line August 23 2008 A list of nine stars whose velocities in the line of sight are variable W W Campbell and W H Wright Astrophysical Journal 12 November 1900 pp 254 257 Bibcode 1900ApJ 12 254C doi 10 1086 140765 The Spectroscopic Binary h Andromedae Katherine C Gordon Astrophysical Journal 103 January 1946 pp 13 15 Bibcode 1946ApJ 103 13G 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 EditImage h Andromedae Retrieved from https en wikipedia org w index php title Eta Andromedae amp oldid 1079511147, wikipedia, wiki, book, books, library,

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