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Xi Boötis A/B
	; Location of ξ Boötis (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Boötes
Right ascension	14h 51m 23.37993s
Declination	+19° 06′ 01.6994″
Apparent magnitude (V)	4.70/6.97
Characteristics
Spectral type	G8 Ve + K4 Ve
U−B color index	0.24/1.15
B−V color index	0.73/1.15
R−I color index	0.43 / 0.28
Variable type	BY Draconis/None; flare star
Astrometry
ξ Boo A
Radial velocity (Rv)	+3.0 km/s
Proper motion (μ)	RA: 127.468±0.126 mas/yr ; Dec.: −40.569±0.129 mas/yr
Parallax (π)	148.0695 ± 0.1317 mas
Distance	22.03 ± 0.02 ly ; (6.754 ± 0.006 pc)
Absolute magnitude (MV)	5.54±0.007
ξ Boo B
Proper motion (μ)	RA: 133.376±0.041 mas/yr ; Dec.: −182.059±0.045 mas/yr
Parallax (π)	148.1793 ± 0.0546 mas
Distance	22.011 ± 0.008 ly ; (6.749 ± 0.002 pc)
Orbit
Companion	Xi Boötis B
Period (P)	151.505±0.170 yr
Semi-major axis (a)	4.9044±0.0027″
Eccentricity (e)	0.5117±0.0006
Inclination (i)	140.037±0.095°
Longitude of the node (Ω)	168.100±0.164°
Periastron epoch (T)	1,909.361±0.024
Argument of periastron (ω); (secondary)	23.917±0.214°
Details
ξ Boo A
Mass	0.88±0.03 M☉
Radius	0.817±0.007 R☉
Luminosity	0.562±0.036 L☉
Surface gravity (log g)	4.561±0.017 cgs
Temperature	5,545±92 K
Metallicity [Fe/H]	−0.10±0.04 dex
Rotation	6.2 d
Age	200 Myr
ξ Boo B
Mass	0.66±0.07 M☉
Radius	0.61 R☉
Luminosity (visual, LV)	0.061 L☉
Temperature	4,350±150 K
Rotation	11.5 d
Other designations
	ξ Boo, 37 Boötis, BD+19°2870, HD 131156, HIP 72659, HR 5544, SAO 101250
Database references
SIMBAD	data
ARICNS	data

Xi Boötis, Latinised from ξ Boötis, is a binary star^[10] system located at a distance of 22 light-years away from Earth. It is the nearest visible star in the constellation Boötes. The brighter, primary component of the pair has a visual magnitude of 4.70, making it visible to the naked eye.

Properties

A light curve for Xi Bootis, showing the average of the b and y magnitudes as a function of time. Adapted from Lockwood *et al.* (2007)^[11]

The primary star in this system is a BY Draconis variable with an apparent magnitude that varies from +4.52 to +4.67 with a period just over 10 days long, and is classified as a G-type main-sequence star. The magnetic activity in the star's chromosphere varies with time, but no activity cycle has yet been found.^[12] It has 88% of the mass and 82% of the radius of the Sun, but shines with just 56% the Sun's luminosity.^[7] The secondary component is a K-type star with just 66% of the Sun's mass and 61% of the Sun's radius. As of 2019, it is located at an angular separation of 5.20″ from the primary, along a position angle of 298°.^[13]

The pair follow a wide, highly elliptical orbit around their common barycenter, completing an orbit every 151.5 years. Radial velocities taken of the primary as part of an extrasolar planet search show a linear trend in the velocities which is likely due to the secondary star.^[14] The pair can be resolved even through smaller telescopes. The binary system contains some of the closest young solar-type stars to the Sun, with a system age of about 200 million years old.^[9]

The primary star (A) has been identified as a candidate for possessing a Kuiper-like belt,^[15] based on infrared observations. The estimated minimum mass of this dust disk is 2.4 times the mass of the Earth's Moon. (Compare to the value of 8.2 lunar masses for the Kuiper belt.)^[16]

A necessary condition for the existence of a planet in this system are stable zones where the object can remain in orbit for long intervals. For hypothetical planets in a circular orbit around the individual members of this star system, this maximum orbital radius is computed to be 3.8 AU for the primary and 3.5 AU for the secondary. A planet orbiting outside of both stars would need to be at least 108 AU distant.^[17]

References

^ ^a ^b van Leeuwen, Floor (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752v1, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600 Note: see VizieR catalogue I/311.
^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, vol. 30, University of Toronto: International Astronomical Union, p. 57, Bibcode:1967IAUS...30...57E
^ ^a ^b ^c Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ Park, Sunkyung; et al. (2013), "Wilson-Bappu Effect: Extended to Surface Gravity", The Astronomical Journal, 146 (4): 73, arXiv:1307.0592, Bibcode:2013AJ....146...73P, doi:10.1088/0004-6256/146/4/73, S2CID 119187733.
^ ^a ^b ^c Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ Wielen, R. (November 1962), "Automatic orbit computation for visual binaries", Astronomical Journal, 67: 599–607, Bibcode:1962AJ.....67..599W, doi:10.1086/108791 The data is from Orbit #3; the solution used by the 6th Washington Double Star catalogue for WDS 14514+1906 Archived 2012-02-03 at the Wayback Machine.
^ ^a ^b ^c ^d ^e ^f ^g Karovicova, I.; White, T. R.; Nordlander, T.; Casagrande, L.; Ireland, M.; Huber, D. (2022). "Fundamental stellar parameters of benchmark stars from CHARA interferometry -- II. Dwarf stars". Astronomy & Astrophysics. 658: A47. arXiv:2109.06203. Bibcode:2022A&A...658A..47K. doi:10.1051/0004-6361/202141833. S2CID 219558406.
^ ^a ^b ^c Wood, Brian E.; Linsky, Jeffrey L. (July 2010), "Resolving the ξ Boo Binary with Chandra, and Revealing the Spectral Type Dependence of the Coronal "FIP Effect"", The Astrophysical Journal, 717 (2): 1279–1290, arXiv:1005.3281, Bibcode:2010ApJ...717.1279W, doi:10.1088/0004-637X/717/2/1279, S2CID 53394680
^ ^a ^b Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008), "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics", The Astrophysical Journal, 687 (2): 1264–1293, arXiv:0807.1686, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785, S2CID 27151456
^ ^a ^b ^c Fernandes, J.; et al. (October 1998), "Fundamental stellar parameters for nearby visual binary stars: eta Cas, XI Boo, 70 OPH and 85 Peg. Helium abundance, age and mixing length parameter for low mass stars", Astronomy and Astrophysics, 338: 455–464, Bibcode:1998A&A...338..455F
^ Lockwood, G. W.; Skiff, B. A.; Henry, Gregory W.; Henry, Stephen; Radick, R. R.; Baliunas, S. L.; Donahue, R. A.; Soon, W. (July 2007). "Patterns of Photometric and Chromospheric Variation among Sun-like Stars: A 20 Year Perspective". The Astrophysical Journal Supplement Series. 171 (1): 260–303. arXiv:astro-ph/0703408. Bibcode:2007ApJS..171..260L. doi:10.1086/516752. S2CID 18775739. Retrieved 1 July 2022.
^ Finley, Adam J.; et al. (May 2019). "The Effect of Magnetic Variability on Stellar Angular Momentum Loss. II. The Sun, 61 Cygni A, ɛ Eridani, ξ Bootis A, and τ Bootis A". The Astrophysical Journal. 876 (1): 14. arXiv:1903.09871. Bibcode:2019ApJ...876...44F. doi:10.3847/1538-4357/ab12d2. S2CID 85500195. 44.
^ Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. Retrieved 2015-07-22.
^ Howard, Andrew W.; Fulton, Benjamin J. (2016). "Limits on Planetary Companions from Doppler Surveys of Nearby Stars". Publications of the Astronomical Society of the Pacific. 128 (969). 114401. arXiv:1606.03134. Bibcode:2016PASP..128k4401H. doi:10.1088/1538-3873/128/969/114401. S2CID 118503912.
^ Hinshaw, Gary (February 3, 1997), Science Requirements Document (PDF), NASA JPL, archived from the original (PDF) on 2006-05-29, retrieved 2006-08-10
^ Holmes, E. K.; et al. (2003), "A Survey of Nearby Main-Sequence Stars for Submillimeter Emission", The Astronomical Journal, 125 (6): 3334–3343, Bibcode:2003AJ....125.3334H, doi:10.1086/375202
^ Jaime, Luisa G.; et al. (December 2012), "Regions of dynamical stability for discs and planets in binary stars of the solar neighbourhood", Monthly Notices of the Royal Astronomical Society, 427 (4): 2723–2733, arXiv:1208.2051, Bibcode:2012MNRAS.427.2723J, doi:10.1111/j.1365-2966.2012.21839.x, S2CID 118570249.