44 Boötis

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44 Boötis
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension 15h 03m 47.29565s[1]
Declination +47° 39′ 14.6228″[1]
Apparent magnitude (V) 4.75[2] (5.136 / 6.004)[3]
Spectral type G0Vnv[4] + (K0V + K4V)[5]
U−B color index 0.09[2]
B−V color index 0.65[2]
Variable type W UMa
Radial velocity (Rv)-17.89[6] km/s
Proper motion (μ) RA: -445.84[1] mas/yr
Dec.: 19.86[1] mas/yr
Parallax (π)78.39 ± 1.03[7] mas
Distance41.6 ± 0.5 ly
(12.8 ± 0.2 pc)
Absolute magnitude (MV)+2.211[7] / +5.38[8]
Primary44 Boo A
Period (P)209.8 ± 3.3 yr
Semi-major axis (a)3.666 ± 0.021″
Eccentricity (e)0.5111 ± 0.0065
Inclination (i)83.55 ± 0.05°
Longitude of the node (Ω)57.14 ± 0.06°
Periastron epoch (T)B 2012.04 ± 0.26
Argument of periastron (ω)
39.86 ± 0.68°
Period (P)0.267818 days
Eccentricity (e)0.0
Semi-amplitude (K1)
231.31 km/s
Semi-amplitude (K2)
112.70 km/s
44 Boo A
Mass1.04 ± 0.10[9] M
Luminosity1.552[3] L
Surface gravity (log g)4.33[10] cgs
Temperature5,877[10] K
Metallicity [Fe/H]-0.24[10] dex
Age1.4–1.5[11] Gyr
44 Boo B
Mass1.28 ± 0.02[9] M
Other designations
i Boötis, i Boo, ADS 9494, CCDM 15038+4739, BD+48°2259, Gl 575, HD 133640, HIP 73695, HR 5618, SAO 45357.[12]
Database references

44 Boötis or i Boötis is a triple star system in the constellation Boötes. It is approximately 41.6 light years from Earth.

The primary component, 44 Boötis A, is a yellow-white G-type main sequence dwarf with a mean apparent magnitude of +4.83. The companion component, 44 Boötis B, is a W Ursae Majoris variable spectroscopic binary. The variability of this star system was discovered by English astronomer William Herschel.[13] The brightness of the binary varies from magnitude +5.8 to +6.40 with a period of 6.43 hours. The components of the eclipsing binary are close enough to allow their stellar envelopes to overlap, or at least nearly so.[14]

The 44 Boötis system is 42 light-years (13 parsecs) from Earth.[7] It also may show signs of an infrared excess, implying the existence of a dust disk that absorbs visible light and re-emits it as infrared light. The dust would have a blackbody temperature of about 23 K, situated up to 182 au from the parent star.[3]


  1. ^ a b c d van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ^ a b c Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data, SIMBAD, Bibcode:1986EgUBV........0M.
  3. ^ a b c Montesinos, B.; et al. (September 2016), "Incidence of debris discs around FGK stars in the solar neighbourhood", Astronomy & Astrophysics, 593: 31, arXiv:1605.05837, Bibcode:2016A&A...593A..51M, doi:10.1051/0004-6361/201628329, A51.
  4. ^ Gray, R. O.; Napier, M. G.; Winkler, L. I. (April 2001), "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars", The Astronomical Journal, 121 (4): 2148–2158, Bibcode:2001AJ....121.2148G, doi:10.1086/319956.
  5. ^ Zasche, P.; Wolf, M.; Hartkopf, W. I.; Svoboda, P.; Uhlař, R.; Liakos, A.; Gazeas, K. (2009). "A Catalog of Visual Double and Multiple Stars with Eclipsing Components". The Astronomical Journal. 138 (2): 664. arXiv:0907.5172. Bibcode:2009AJ....138..664Z. doi:10.1088/0004-6256/138/2/664.
  6. ^ Bilir, S.; et al. (February 2005), "Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation", Monthly Notices of the Royal Astronomical Society, 357 (2): 497–517, arXiv:astro-ph/0411291, Bibcode:2005MNRAS.357..497B, doi:10.1111/j.1365-2966.2005.08609.x.
  7. ^ a b c Eker, Z.; et al. (2009), "New absolute magnitude calibrations for W Ursa Majoris type binaries", Astronomische Nachrichten, 330 (1): 68–77, arXiv:0807.4989, Bibcode:2009AN....330...68E, doi:10.1002/asna.200811041.
  8. ^ a b Lu, Wenxian; Rucinski, Slavek M; Ogłoza, Waldemar (2001). "Radial Velocity Studies of Close Binary Stars. IV". The Astronomical Journal. 122: 402. arXiv:astro-ph/0104065. Bibcode:2001AJ....122..402L. doi:10.1086/321131.
  9. ^ a b c Zirm, Henry (2011). "The Rapid Convergence of 44 Boötis with Revised Orbit and Updated Ephemerides" (PDF). Journal of Double Star Observations. 7 (1): 24–36. Bibcode:2011JDSO....7...24Z.
  10. ^ a b c Ramírez, I.; et al. (September 2012), "Lithium Abundances in nearby FGK Dwarf and Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, and Exoplanets", The Astrophysical Journal, 756 (1): 46, arXiv:1207.0499, Bibcode:2012ApJ...756...46R, doi:10.1088/0004-637X/756/1/46.
  11. ^ 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.
  12. ^ "* i Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2015-04-22.
  13. ^ Percy, John R. (2007), Understanding Variable Stars, Cambridge University Press, p. 3, ISBN 1139463284.
  14. ^ Kaler, Jim. "Asellus Tertius". Retrieved 2017-09-06.

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