Zeta Boötis

ζ Boötis
Location of ζ Boötis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension 14h 41m 08.95158s[1]
Declination +13° 43′ 41.8967″[1]
Apparent magnitude (V) 3.78[2](4.46 + 4.55)[3]
Characteristics
Spectral type A1V[4]
U−B color index +0.05[2]
B−V color index +0.05[2]
Astrometry
Radial velocity (Rv)−8.5±0.6[5] km/s
Proper motion (μ) RA: +51.95 mas/yr[1]
Dec.: -11.08 mas/yr[1]
Parallax (π)18.56±0.76 mas[1]
Distance176 ± 7 ly
(54 ± 2 pc)
Absolute magnitude (MV)+0.13[6]
Details[7]
A
Mass2.21+0.14
−0.05 M☉
Radius2.6+0.3
−0.4 R☉
Temperature8,800+1,000
−600 K
Age560+150
−240 Myr
B
Mass2.15+0.10
−0.03 M☉
Radius2.4±0.3 R☉
Temperature8,750+800
−550 K
Age560+150
−240 Myr
HIP 71759
Mass1.655±0.131[8] M☉
Radius1.738±0.114[8] R☉
Luminosity8.85±0.28[8] L☉
Temperature7,570±253[8] K
Orbit[7]
PrimaryA
CompanionB
Period (P)125.04+0.24
−0.21 years
Semi-major axis (a)41.84+0.46
−0.44 au
Eccentricity (e)0.98045
Inclination (i)125.88±0.16°
Longitude of the node (Ω)176.63±0.16°
Periastron epoch (T)2023.9548
Argument of periastron (ω)
(secondary)		62.08+0.13
−0.14°
Other designations
ζ Boo, 30 Boötis, BD+14° 2770, GC 19777, HIP 71795, SAO 101145, ADS 9343, CCDM 14411+1344, WDS J14411+1344[9]
A: HD 129247, HR 5478[10]
B: HD 129246, HR 5477[11]
Database references
SIMBADdata

Zeta Boötis, Latinized from ζ Boötis, is a triple star system in the constellation of Boötes. They have the Flamsteed designation 30 Boötis; Zeta Boötis is the Bayer designation. This system is visible to the naked eye with a combined apparent magnitude of +3.78.[2] The individual magnitudes differ slightly, with component A having a magnitude of 4.46 and component B at the slightly dimmer magnitude 4.55.[3] It is located at a distance of approximately 180 light years based on parallax,[1] but is drifting closer with a radial velocity of −9 km/s.[5]

The duplicity of this star was discovered by English astronomer William Herschel in 1796, and their changing positions have been tracked from 1823 onward.[12] They complete an orbit every 125 years. The orbit of this pair has a very high eccentricity of 0.98045, bringing the stars within 0.818 au at their closest approach (periastron). The eccentricity of this system is possibly the second-highest known, after HIP 26245, whose eccentricity is 0.985±0.002. The last periastron occured during November 2023.[7] Considering the extreme nature of their orbit, it is unlikely that any exoplanets could have stable orbits around either star.[13]

Together with the distant companion HIP 71759, Zeta Boötis make a triple star system. This distant star has an estimated orbital period of three million years, being at an observed distance of 41,300 au (6,180×10^9 km; 0.653 ly) from the inner pair.[14]

In 1976, T. W. Edwards found a stellar classification of A2III for both components, suggesting they may be evolved A-type giant stars. Helmut A. Abt reported a class of A2V in 1981, which matches an A-type main-sequence star.[15] Abt and Nidia Morrell updated the classification to A1V in 1995.[4]

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (November 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. 1 2 3 4 Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
  3. 1 2 Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  4. 1 2 Abt, Helmut A.; Morrell, Nidia I. (July 1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182.
  5. 1 2 Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  6. ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  7. 1 2 3 Waisberg, Idel; Klein, Ygal; Katz, Boaz (2025-04-24), Which is the most eccentric binary known? Insights from the 2023/4 pericenter passages of Zeta Boötis and Eta Ophiuchi, arXiv:2504.17858
  8. 1 2 3 4 Hardegree-Ullman, Kevin K.; Apai, Dániel; Bergsten, Galen J.; Pascucci, Ilaria; López-Morales, Mercedes (2023-06-01). "Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O2 Levels in Nearby Transiting Habitable-zone Exoplanets". The Astronomical Journal. 165 (6): 267. arXiv:2304.12490. Bibcode:2023AJ....165..267H. doi:10.3847/1538-3881/acd1ec. ISSN 0004-6256.
  9. ↑ "zet Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-31.
  10. ↑ "zet Boo A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-31.
  11. ↑ "zet Boo B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-31.
  12. ↑ Wierzbiński, St. (1956), "Orbites des étoiles doubles", Acta Astronomica, 6: 82, Bibcode:1956AcA.....6...82W.
  13. ↑ Muterspaugh, Matthew W.; et al. (December 2010), "The Phases Differential Astrometry Data Archive. III. Limits to Tertiary Companions", The Astronomical Journal, 140 (6): 1631–1645, arXiv:1010.4044, Bibcode:2010AJ....140.1631M, doi:10.1088/0004-6256/140/6/1631, S2CID 9272936.
  14. ↑ Waisberg, Idel; Klein, Ygal; Katz, Boaz (March 2024). "Hidden Companions to Intermediate-mass Stars. XVI. Unveiling a 41,300 au Companion to the Very Eccentric Binary Zeta Boötis". Research Notes of the AAS. 8 (3): 55. Bibcode:2024RNAAS...8...55W. doi:10.3847/2515-5172/ad2df5. ISSN 2515-5172.
  15. ↑ Abt, H. A. (1981), "Visual multiples. VII. MK classifications", The Astrophysical Journal Supplement Series, 45: 437, Bibcode:1981ApJS...45..437A, doi:10.1086/190719.
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