46 Boötis

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 article is about b Boötis. It is not to be confused with β (Beta) Boötis.

46 Boötis

Observation data Epoch J2000      Equinox J2000
Constellation	Boötes
Right ascension	15^h 08^m 23.78241^s[1]
Declination	+26° 18′ 04.1464″[1]
Apparent magnitude (V)	5.67[2]
Characteristics
Spectral type	K2 III[3]
U−B color index	+1.24[4]
B−V color index	+1.240±0.015[2]
Astrometry
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
Distance	478 ± 6 ly (146 ± 2 pc)
Absolute magnitude (MV)	−0.31[2]
Orbit[5]
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) (secondary)	175.3±0.7[5]°
Semi-amplitude (K1) (primary)	9.25±0.10[5] km/s
Details
46 Boo A
Radius	23.35+0.85 −0.67[1] R☉
Luminosity	175.8±2.8[1] L☉
Temperature	4349+64 −76[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
SIMBAD	data

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]

References

1. 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. 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. 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. 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. Jancart, S.; et al. (October 2005), "Astrometric orbits of S_B^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. "b Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 12, 2019.

External links

• HR 5638
• Image 46 Boötis