Phi Ursae Majoris
Phi Ursae Majoris is located in 100x100
Phi Ursae Majoris

Location of φ Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 09h 52m 06.35437s[1]
Declination +54° 03′ 51.5962″[1]
Apparent magnitude (V) +4.60[2] (5.28 + 5.39)[3]
Characteristics
Spectral type A3 IV + A3 IV[4]
U−B color index +0.08[2]
B−V color index +0.03[2]
Astrometry
Radial velocity (Rv)−14.7±0.3[5] km/s
Proper motion (μ) RA: −6.00[1] mas/yr
Dec.: +19.16[1] mas/yr
Parallax (π)6.41 ± 0.59 mas[1]
Distance510 ± 50 ly
(160 ± 10 pc)
Absolute magnitude (MV)−1.39[6]
Orbit[7]
Period (P)104.6 yr
Semi-major axis (a)0.329″
Eccentricity (e)0.436
Inclination (i)19.4°
Longitude of the node (Ω)132.5°
Periastron epoch (T)1987.52
Argument of periastron (ω)
(secondary)		33.3°
Details
A
Mass3.5±0.2[8] M☉
Luminosity347[8] L☉
Surface gravity (log g)3.69±0.16[9] cgs
Temperature8,769±150[9] K
Metallicity [Fe/H]−0.23±0.08[9] dex
Rotational velocity (v sin i)28[8] km/s
Other designations
φ UMi, 30 Ursae Majoris, BD+54°1331, GC 13559, HD 85235, HIP 48402, HR 3894, SAO 27408, PPM 32355, CCDM J09521+5404AB, WDS J09521+5404AB[10]
Database references
SIMBADdata

Phi Ursae Majoris, Latinized from φ Ursae Majoris, is binary star[11] system in the northern constellation of Ursa Major. It is white-hued and is visible to the naked eye with a combined apparent visual magnitude of +4.60;[2] the primary is magnitude 5.28 while the secondary is magnitude 5.39.[11] The system is located at a distance of approximately 510 light-years (160 parsecs) from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −14.7 km/s.[5] It should make its closest approach at a distance of around 370 light-years in about 4.7 million years.[6]

As of 2017, the components had an angular separation of 0.50″ along a position angle of 304°.[3] They are orbiting each other with a period of 105.4 years and eccentricity of 0.44.[7] Both of components are A-type subgiant stars[12] with a stellar classification of A3 IV.[4]

Phi Ursae Majoris is moving through the galaxy at a speed of 21.6 km/s relative to the Sun. Its projected galactic orbit carries it between 24,000 and 46,000 light-years from the center of the galaxy.[6]

Naming

With τ, h, υ, θ, e, and f, it composed the Arabic asterism Sarīr Banāt al-Na'sh, the Throne of the daughters of Na'sh, and Al-Haud, the Pond.[13] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al-Haud were the title for seven stars: f as Alhaud I, τ as Alhaud II, e as Alhaud III, h as Alhaud IV, θ as Alhaud V, υ as Alhaud VI and this star (φ) as Alhaud VII.[14]

In Chinese, 文昌 (Wén Chāng), meaning Administrative Center, refers to an asterism consisting of φ Ursae Majoris, υ Ursae Majoris, θ Ursae Majoris, 15 Ursae Majoris and 18 Ursae Majoris. Consequently, the Chinese name for φ Ursae Majoris itself is known as 文昌三 (Wén Chāng sān, English: the Third Star of Administrative Center).[15]

References

  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. S2CID 18759600.
  2. ^ a b c d Johnson, H. L. (1966), "UBVRIJKL Photometry of the Bright Stars", Communications of the Lunar and Planetary Laboratory, 4: 99, Bibcode:1966CoLPL...4...99J.
  3. ^ a b Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22
  4. ^ a b Edwards, T. W. (April 1976), "MK classification for visual binary components", Astronomical Journal, 81: 245–249, Bibcode:1976AJ.....81..245E, doi:10.1086/111879.
  5. ^ a b Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  6. ^ a b c 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, S2CID 119257644.
  7. ^ a b Hartkopf, W. I.; et al. (June 30, 2006), Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, retrieved 2017-06-02.
  8. ^ a b c Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
  9. ^ a b c Prugniel, P.; 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, S2CID 54940439.
  10. ^ "phi UMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 February 2017.
  11. ^ a b 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, S2CID 14878976.
  12. ^ Kaler, James B. (April 23, 2010), "PHI UMA (Phi Ursae Majoris)", STARS, retrieved 2019-10-12.
  13. ^ Allen, Richard Hinckley (1899), Star-Names and Their Meanings, New York: G. E. Stechert, p. 442
  14. ^ Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars (PDF), Jet Propulsion Laboratory, California Institute of Technology.
  15. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 16 日
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