Epoch J2000 Equinox J2000
|Right ascension||14h 51m 23.37993s|
|Declination||+19° 06′ 01.6994″|
|Apparent magnitude (V)||4.70/6.97|
|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
|Radial velocity (Rv)||+3.0 km/s|
|Proper motion (μ)||RA: 154.98 mas/yr
Dec.: -66.43 mas/yr
|Parallax (π)||148.98 ± 0.48 mas|
|Distance||21.89 ± 0.07 ly
(6.71 ± 0.02 pc)
|Absolute magnitude (MV)||5.54/7.81|
|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)||1909.361 ± 0.024|
|Argument of periastron (ω)
|23.917 ± 0.214°|
|ξ Boo A|
|Mass||0.90 ± 0.04 M☉|
|Luminosity (visual, LV)||0.6041 ± 0.0040 L☉|
|Temperature||5551 ± 20 K|
|Metallicity [Fe/H]||–0.21 ± 0.08 dex|
|ξ Boo B|
|Mass||0.66 ± 0.07 M☉|
|Luminosity (visual, LV)||0.061 L☉|
|Temperature||4350 ± 150 K|
Xi Boötis (ξ Boo, ξ Boötis) is a binary star system 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.
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. It has 90% of the mass and 83% of the radius of the Sun, but shines with just 60% the Sun's luminosity. The secondary component is a K-type star, with just 66% of the Sun's mass and 61% of the Sun's radius.
The pair follow a wide, highly elliptical orbit around their common barycenter, completing an orbit every 151.5 years. 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.
The primary star (A) has been identified as a candidate for possessing a Kuiper-like belt, 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.)
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.
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- Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E
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