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    18 Boötis

    Topic: Astronomy

     From Handwiki - Reading time: 4 min
    Short description: Star in the constellation Boötes
    18 Boötis
    Observation data
    Equinox J2000.0]] (ICRS)
    Constellation Boötes
    Right ascension  14h 19m 16.27966s[1]
    Declination +13° 00′ 15.4859″[1]
    Apparent magnitude (V) 5.41[2]
    Characteristics
    Spectral type F3 V[3]
    B−V color index 0.385±0.011[2]
    Astrometry
    Radial velocity (Rv)−0.40±0.7[2] km/s
    Proper motion (μ) RA: +105.273[1] mas/yr
    Dec.: −31.389[1] mas/yr
    Parallax (π)38.1262 ± 0.1323[1] mas
    Distance85.5 ± 0.3 ly
    (26.23 ± 0.09 pc)
    Absolute magnitude (MV)3.33[2]
    Details
    Mass1.31[4] M☉
    Radius1.4[5] R☉
    Luminosity3.90[2] L☉
    Surface gravity (log g)4.30[4] cgs
    Temperature6,731±229[4] K
    Metallicity [Fe/H]−0.03±0.04[6] dex
    Rotational velocity (v sin i)40.5±2.0[7] km/s
    Age1.154[4] Gyr
    Other designations
    18 Boo, BD+13°2782, FK5 1372, GJ 3841, HD 125451, HIP 69989, HR 5365, SAO 100975, WDS J14193+1300[8]
    Database references
    SIMBADdata

    18 Boötis is a single[9] star in the northern constellation of Boötes,[8] located about 85 light years away from the Sun.[1] It is visible to the naked eye as a faint, yellow-white hued star with an apparent visual magnitude of 5.41.[2] This object is a suspected member of the Ursa Major Moving Group, based on velocity criteria.[10] It has a magnitude 10.84 optical companion at an angular separation of 163.7″ along a position angle of 219°, as of 2010.[11]

    This is an F-type main-sequence star with a stellar classification of F3 V.[3] Older surveys gave a class of F5 IV,[12] showing the luminosity class of a subgiant star. It shows strong evidence for short-term chromospheric variability, although it is not optically variable.[13]

    18 Boötis is an estimated 1.15[4] billion years old and is spinning with a projected rotational velocity of 40.5 km/s.[7] It has 1.3[4] times the mass of the Sun and 1.4[5] times the Sun's radius. The star is radiating 3.9[2] times the luminosity of the Sun from its photosphere at an effective temperature of 6,731 K.[4] An infrared excess has been detected that suggests a cold debris disk is orbiting 34.9 astronomical unit|AU from the host star with a blackbody temperature fit of 65 K.[5]

    References

    1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
    2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
    3. ↑ 3.0 3.1 Gray, R. O. et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal 132 (1): 161–170, doi:10.1086/504637, Bibcode: 2006AJ....132..161G. 
    4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal 804 (2): 146, doi:10.1088/0004-637X/804/2/146, Bibcode: 2015ApJ...804..146D. 
    5. ↑ 5.0 5.1 5.2 Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series 225 (1): 24, doi:10.3847/0067-0049/225/1/15, 15, Bibcode: 2016ApJS..225...15C. 
    6. ↑ Gáspár, András et al. (2016), "The Correlation between Metallicity and Debris Disk Mass", The Astrophysical Journal 826 (2): 171, doi:10.3847/0004-637x/826/2/171, Bibcode: 2016ApJ...826..171G. 
    7. ↑ 7.0 7.1 Ammler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics 542: A116, doi:10.1051/0004-6361/201118724, Bibcode: 2012A&A...542A.116A. 
    8. ↑ 8.0 8.1 "18 Boo". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=18+Boo. 
    9. ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
    10. ↑ Nakajima, Tadashi; Morino, Jun-Ichi (2012), "Potential Members of Stellar Kinematic Groups within 30 pc of the Sun", The Astronomical Journal 143 (1): 2, doi:10.1088/0004-6256/143/1/2, Bibcode: 2012AJ....143....2N. 
    11. ↑ 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. 
    12. ↑ Eggen, O. J. (1962), "Space-velocity vectors for 3483 stars with proper motion and radial velocity", Royal Observatory Bulletin 51: 79, Bibcode: 1962RGOB...51...79E. 
    13. ↑ Rachford, Brian L.; Foight, Dillon R. (June 2009), "Chromospheric Variability in Early F-Type Stars", The Astrophysical Journal 698 (1): 786–802, doi:10.1088/0004-637X/698/1/786, Bibcode: 2009ApJ...698..786R. 



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