46 Boötis

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46 Boötis
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension  15h 08m 23.78241s[1]
Declination +26° 18′ 04.1464″[1]
Apparent magnitude (V) 5.67[2]
Spectral type K2 III[3]
U−B color index +1.24[4]
B−V color index +1.240±0.015[2]
Radial velocity (Rv)+19.31±0.30[2] km/s
Proper motion (μ) RA: +4.454[1] mas/yr
Dec.: −15.185[1] mas/yr
Parallax (π)6.8288 ± 0.0883[1] mas
Distance478 ± 6 ly
(146 ± 2 pc)
Absolute magnitude (MV)−0.31[2]
Period (P)2,567.1±0.6 d
Semi-major axis (a)11.2 mas[6]
Eccentricity (e)0.8315±0.0027
Inclination (i)62[6]°
Longitude of the node (Ω)82.6±6.6°
Periastron epoch (T)2,448,356.6 JD
Argument of periastron (ω)
Semi-amplitude (K1)
9.25±0.10[5] km/s
46 Boo A
[1] R
Luminosity175.8±2.8[1] L
[1] K
Metallicity [Fe/H]−0.27±0.15[7] dex
Other designations
b Boo, 46 Boo, BD+26°2656, FK5 1396, GC 20367, GJ 578, HD 134320, HIP 74087, HR 5638, SAO 83682[8]
Database references

46 Boötis is a binary star system in the northern constellation of Boötes, located mid-way between α Coronae Borealis and ε Boötis.[5] It has the Bayer designation b Boötis; 46 Boötis is the Flamsteed designation.[8] The system lies 478 light years away from the Sun based on parallax,[1] and is visible to the naked eye as a faint, orange-hued star with a combined apparent visual magnitude of 5.67.[2] It is moving away from the Earth with a heliocentric radial velocity of +19 km/s.[2] The light from this system displays an unusually high level of polarization due to interstellar dust.[5]

This is a single-lined spectroscopic binary with an orbital period of 7.03 years and a large eccentricity of 0.83.[5] The primary member, designated component A, is an aging giant star with a stellar classification of K2 III.[3] As a consequence of exhausting the hydrogen at its core, it has expanded to 23[1] times the Sun's radius. It is radiating 176[1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,349 K.[1] The companion star, component B, is most likely a lower main sequence star with 0.6–0.8 times the Sun's mass.[6]


  1. ^ a b c d e f g h i j k l 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.
  2. ^ a b c d e f 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.
  3. ^ a b Sato, K.; Kuji, S. (November 1990), "MK classification and photometry of stars used for time and latitude observations at Mizusawa and Washington", Astronomy and Astrophysics Supplement Series, 85 (3): 1069–1087, Bibcode:1990A&AS...85.1069S.
  4. ^ Guetter, H. H.; Hewitt, A. V. (1984), "Photoelectric UBV photometry for 317 PZT and VZT stars", Astronomical Society of the Pacific, 96: 441–443, Bibcode:1984PASP...96..441G, doi:10.1086/131362.
  5. ^ a b c d e f Griffin, R. F.; Eitter, J. J. (December 1999), "Spectroscopic binary orbits from photoelectric radial velocities. Paper 149: 46 Bootis", The Observatory, 119: 320–328, Bibcode:1999Obs...119..320G.
  6. ^ a b c Jancart, S.; et al. (October 2005), "Astrometric orbits of SB^9 stars", Astronomy and Astrophysics, 442 (1): 365–380, arXiv:astro-ph/0507695, Bibcode:2005A&A...442..365J, doi:10.1051/0004-6361:20053003.
  7. ^ Taylor, Benjamin J. (June 1991), "A Critical Appraisal of Published Values of [Fe/H] for K II--IV Stars", Astrophysical Journal Supplement, 76: 715, Bibcode:1991ApJS...76..715T, doi:10.1086/191579
  8. ^ a b "b Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 12, 2019.

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