Astronomy:Xi Boötis

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Short description: Star in the constellation Boötes
Xi Boötis
Diagram showing star positions and boundaries of the Boötes constellation and its surroundings
Diagram showing star positions and boundaries of the Boötes constellation and its surroundings

Location of ξ Boötis (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Boötes
Right ascension  14h 51m 23.37993s[1]
Declination +19° 06′ 01.6994″[1]
Apparent magnitude (V) 4.675 + 6.816[2]
Characteristics
Spectral type G8 Ve + K4 Ve[3]
B−V color index 0.725/1.165[2]
Variable type BY Dra[4]
Astrometry
ξ Boo A
Radial velocity (Rv)+1.59±0.12[1] km/s
Proper motion (μ) RA: 127.468[1] mas/yr
Dec.: −40.569[1] mas/yr
Parallax (π)148.0695 ± 0.1317[1] mas
Distance22.03 ± 0.02 ly
(6.754 ± 0.006 pc)
Absolute magnitude (MV)5.54±0.007[5]
ξ Boo B
Radial velocity (Rv)+2.31±0.13[6] km/s
Proper motion (μ) RA: 133.376 mas/yr
Dec.: −182.059 mas/yr
Parallax (π)148.1793 ± 0.0546[6] mas
Distance22.011 ± 0.008 ly
(6.749 ± 0.002 pc)
Orbit[7]
Period (P)152.46±0.07 years
Semi-major axis (a)4.91985±0.00266″
Eccentricity (e)0.5141±0.0005
Inclination (i)140.538±0.065°
Longitude of the node (Ω)167.938±0.162°
Periastron epoch (T)2061.90±0.09
Argument of periastron (ω)
(secondary)		24.015±0.258°
Details
ξ Boo A
Mass0.88±0.03[8] M☉
Radius0.817±0.007[8] R☉
Luminosity0.562±0.036[8] L☉
Surface gravity (log g)4.561±0.017[8] cgs
Temperature5,545±92[8] K
Metallicity [Fe/H]−0.10±0.04[8] dex
Rotation6.2 d[9]
Age200[10] Myr
ξ Boo B
Mass0.66±0.07[11] M☉
Radius0.61[9] R☉
Luminosity (visual, LV)0.061 L☉
Temperature4,350±150[11] K
Rotation11.5[9] days
Other designations
ξ Boo, 37 Boötis, BD+19°2870, GC 19991, GJ 566, HD 131156, HIP 72659, HR 5544, SAO 101250, WDS J14514+1906[12]
Database references
SIMBADThe system
A
B
ARICNSdata

Xi Boötis is a binary star[11] system in the northern constellation of Boötes. Its name is a Bayer designation that is Latinised from ξ Boötis, and abbreviated Xi Boo or ξ Boo. This is the nearest visible star in the constellation Boötes. The brighter, primary component of the pair has a typical apparent visual magnitude of 4.70, making it visible to the naked eye. Based on parallax measurements, it is located at a distance of 22.0 light-years (6.7 parsecs) from Earth. The pair are drifting further from the Sun with a radial velocity of +2 km/s.[1]

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)[13]

The primary star in this system is a G-type main-sequence star with a stellar classification of G8 Ve,[3] where the 'e' notation indicates emission lines in the spectrum. It 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. The magnetic activity in the star's chromosphere varies with time, but no activity cycle has been found (as of 2019).[14] It has 88% of the mass and 82% of the radius of the Sun, but shines with just 56% the Sun's luminosity.[8]

The secondary component is a smaller K-type main-sequence star with a class of K4 Ve.[3] It has 66% of the Sun's mass and 61% of the Sun's radius. The star is radiating just 6.1% of the luminosity of the Sun from its photosphere at an effective temperature of 4,350 K.[11] This gives it an apparent visual magnitude of 6.8,[2] which by itself would be a challenge to view with the naked eye. As of 2019, it is located at an angular separation of 5.20″ from the primary, along a position angle of 298°.[15]

The pair follow a wide, highly elliptical orbit around their common barycenter, completing an orbit every 152.5 years.[7] Radial velocity measurements taken of the primary as part of an extrasolar planet search show a linear trend in the velocities that is likely due to the secondary star.[16] The pair can be resolved using a small telescope. The binary system contains two of the closest young solar-type stars to the Sun, with a system age of about 200 million years old.[10]

The primary star, component A, has been identified as a candidate for possessing a Kuiper-like belt,[17] 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.)[18]

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 astronomical unit|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.[19]

See also

  • List of nearest K-type stars

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 Høg, E. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars" (in en). Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 3.2 Levato, H.; Abt, H. A. (August 1978). "Spectral types in the Ursa Major stream". Publications of the Astronomical Society of the Pacific 90: 429−433. doi:10.1086/130352. Bibcode: 1978PASP...90..429L. 
  4. ↑ Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. GCVS 5.1 61 (1): 80–88. Bibcode: 2017ARep...61...80S. 
  5. ↑ Park, Sunkyung et al. (2013). "Wilson-Bappu Effect: Extended to Surface Gravity". The Astronomical Journal 146 (4): 73. doi:10.1088/0004-6256/146/4/73. Bibcode: 2013AJ....146...73P. 
  6. ↑ 6.0 6.1 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  7. ↑ 7.0 7.1 Izmailov, Igor; Khovritchev, Maxim (January 2025). "New Orbital Parameters of 850 Wide Visual Binary Stars and Their Statistical Properties" (in en). Research in Astronomy and Astrophysics 25 (1): 015016. doi:10.1088/1674-4527/ad9da3. ISSN 1674-4527. Bibcode: 2025RAA....25a5016I. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 Karovicova, I. et al. (2022). "Fundamental stellar parameters of benchmark stars from CHARA interferometry -- II. Dwarf stars". Astronomy & Astrophysics 658: A47. doi:10.1051/0004-6361/202141833. Bibcode: 2022A&A...658A..47K. 
  9. ↑ 9.0 9.1 9.2 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. doi:10.1088/0004-637X/717/2/1279. Bibcode: 2010ApJ...717.1279W. 
  10. ↑ 10.0 10.1 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. doi:10.1086/591785. Bibcode: 2008ApJ...687.1264M. 
  11. ↑ 11.0 11.1 11.2 11.3 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. 
  12. ↑ "Xi Boo". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Xi+Boo. 
  13. ↑ Lockwood, G. W. et al. (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. doi:10.1086/516752. Bibcode: 2007ApJS..171..260L. https://iopscience.iop.org/article/10.1086/516752/pdf. Retrieved 1 July 2022. 
  14. ↑ 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. doi:10.3847/1538-4357/ab12d2. 44. Bibcode: 2019ApJ...876...44F. 
  15. ↑ Mason, B. D. et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal 122 (6): 3466. doi:10.1086/323920. Bibcode: 2001AJ....122.3466M. http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=B/wds. Retrieved 2015-07-22. 
  16. ↑ 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. doi:10.1088/1538-3873/128/969/114401. Bibcode: 2016PASP..128k4401H. 
  17. ↑ Hinshaw, Gary (February 3, 1997). Science Requirements Document. NASA JPL. http://ssc.spitzer.caltech.edu/documents/SRD.pdf. Retrieved 2006-08-10. 
  18. ↑ Holmes, E. K. et al. (2003). "A Survey of Nearby Main-Sequence Stars for Submillimeter Emission". The Astronomical Journal 125 (6): 3334–3343. doi:10.1086/375202. Bibcode: 2003AJ....125.3334H. 
  19. ↑ 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. doi:10.1111/j.1365-2966.2012.21839.x. Bibcode: 2012MNRAS.427.2723J. 



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