44 Boötis

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This article is about i Boötis. It is not to be confused with ι Boötis.
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]
Spectral type G0Vnv[3] + F
U−B color index 0.09[2]
B−V color index 0.65[2]
Variable type W UMa variable
Radial velocity (Rv) -17.89[4] km/s
Proper motion (μ) RA: -445.84[1] mas/yr
Dec.: 19.86[1] mas/yr
Parallax (π) 78.39 ± 1.03[5] mas
Distance 41.6 ± 0.5 ly
(12.8 ± 0.2 pc)
Absolute magnitude (MV) 2.211[5]
44 Boo A
Surface gravity (log g) 4.33[6] cgs
Temperature 5,877[6] K
Metallicity [Fe/H] -0.24[6] dex
Age 1.4–1.5[7] Gyr
Primary 44 Boo A
Period (P) 209.8 yr
Semi-major axis (a) 3.666"
Inclination (i) 83.6°
Longitude of the node (Ω) 57.1°
Argument of periastron (ω)
Other designations
i Boötis, i Boo, ADS 9494, CCDM 15038+4739, BD+48°2259, Gl 575, HD 133640, HIP 73695, HR 5618, SAO 45357.[9]
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.[10] 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 separated by 0.008 Astronomical Units, roughly 3 times the distance of the Moon from Earth, and close enough to allow their stellar envelopes to overlap.

The 44 Boötis system is 42 light-years (13 parsecs) from Earth.[5]


  1. ^ a b c d van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, 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 ^ a b c Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data, SIMBAD, Bibcode:1986EgUBV........0M. 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. ^ 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. 
  4. ^ 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/0411291Freely accessible, Bibcode:2005MNRAS.357..497B, doi:10.1111/j.1365-2966.2005.08609.x. 
  5. ^ 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:0807.4989Freely accessible, Bibcode:2009AN....330...68E, doi:10.1002/asna.200811041. 
  6. ^ 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:1207.0499Freely accessible, Bibcode:2012ApJ...756...46R, doi:10.1088/0004-637X/756/1/46. 
  7. ^ 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:0807.1686Freely accessible, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785. 
  8. ^ Agati, J.-L.; et al. (February 2015), "Are the orbital poles of binary stars in the solar neighbourhood anisotropically distributed?", Astronomy & Astrophysics, 574: 32, arXiv:1411.4919Freely accessible, Bibcode:2015A&A...574A...6A, doi:10.1051/0004-6361/201323056, A6. 
  9. ^ "i Boo -- Eclipsing binary of W UMa type (contact binary)", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2015-04-22. 
  10. ^ Percy, John R. (2007), Understanding Variable Stars, Cambridge University Press, p. 3, ISBN 1139463284. 

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