Phi Boötis

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Phi Boötis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Boötes
Right ascension  15h 37m 49.59790s[1]
Declination +40° 21′ 12.3635″[1]
Apparent magnitude (V) +5.24[2]
Spectral type G7 III-IV Fe-2[3]
U−B color index +0.53[2]
B−V color index +0.88[2]
Radial velocity (Rv)−10.62±0.30[4] km/s
Proper motion (μ) RA: +61.23[1] mas/yr
Dec.: +60.09[1] mas/yr
Parallax (π)19.22 ± 0.24[1] mas
Distance170 ± 2 ly
(52.0 ± 0.6 pc)
Absolute magnitude (MV)+1.67[5]
Mass1.43[5] M
Radius5[4] R
Luminosity17[4] L
Surface gravity (log g)2.82±0.14[6] cgs
Temperature4,945±57[6] K
Metallicity [Fe/H]−0.51±0.06[6] dex
Rotational velocity (v sin i)0.0[4] km/s
Age3.16[5] Gyr
Other designations
φ Boo, 54 Boötis, BD+40° 2907, FK5 580, GC 21032, HD 139641, HIP 76534, HR 5823, SAO 45643[7]
Database references

Phi Boötis (φ Boötis) is a single,[8] yellow-hued star in the northern constellation of Boötes. It is dimly visible to the naked eye with an apparent visual magnitude of +5.24.[2] Based upon an annual parallax shift of 19.22 mas as seen from the Earth,[1] it is located 170 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.09 due to interstellar dust.[5] It is moving closer to the Sun with a radial velocity of −10.6 km/s.[4]

The stellar classification of Phi Boötis is G7 III-IV Fe-2,[3] which would suggest it is an evolving G-type star that shows spectral traits of both a subgiant and a giant star. However, Alves (2000) has it listed as a member of the so-called "red clump", indicating that it is an aging giant star that is generating energy through helium fusion at its core.[9] The 'Fe-2' suffix notation in its class means that it displays a significant underabundance of iron in its spectrum. Around three billion years old,[5] Phi Boötis has an estimated 1.43[5] times the mass of the Sun and 5[4] times the Sun's radius. It is radiating 17[4] times the Sun's luminosity from its photosphere at an effective temperature of about 4,945 K.[6]


  1. ^ a b c d e f van Leeuwen, F. (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 d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
  3. ^ a b Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", The Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  4. ^ a b c d e f g Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
  5. ^ a b c d e f Takeda, Yoichi; et al. (August 2008), "Stellar Parameters and Elemental Abundances of Late-G Giants", Publications of the Astronomical Society of Japan, 60 (4): 781–802, arXiv:0805.2434, Bibcode:2008PASJ...60..781T, doi:10.1093/pasj/60.4.781.
  6. ^ a b c d Prugniel, Ph.; et al. (2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769.
  7. ^ "phi Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-09-09.
  8. ^ 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.
  9. ^ Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278.


  • Hoffleit; et al. (1991), "HR 5823", Bright Star Catalogue (5th Revised ed.), retrieved 2017-09-11.
  • "phi Boo", Aladin previewer, Centre de Données astronomiques de Strasbourg, retrieved 2017-09-11.