18 Boötis

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]

18 Boötis
Observation data
Epoch J2000      Equinox J2000
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

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 AU from the host star with a blackbody temperature fit of 65 K.[5]

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. 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, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
  4. 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, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146.
  5. Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series, 225 (1): 24, arXiv:1606.01134, Bibcode:2016ApJS..225...15C, doi:10.3847/0067-0049/225/1/15, 15.
  6. Gáspár, András; et al. (2016), "The Correlation between Metallicity and Debris Disk Mass", The Astrophysical Journal, 826 (2): 171, arXiv:1604.07403, Bibcode:2016ApJ...826..171G, doi:10.3847/0004-637x/826/2/171.
  7. Ammler-von Eiff, M.; Reiners, A. (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, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724.
  8. "18 Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 8, 2019.
  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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  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, Bibcode:2012AJ....143....2N, doi:10.1088/0004-6256/143/1/2.
  11. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, 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, 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, arXiv:0904.1620, Bibcode:2009ApJ...698..786R, doi:10.1088/0004-637X/698/1/786.
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