4 Ursae Minoris
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Minor
Right ascension 14h 08m 50.92654s[1]
Declination +77° 32′ 51.0466″[1]
Apparent magnitude (V) 4.80[2]
Characteristics
Spectral type K3-IIIb Fe-0.5[3]
B−V color index 1.368[4]
Astrometry
Radial velocity (Rv)+5.86±0.10[5] km/s
Proper motion (μ) RA: −30.45[1] mas/yr
Dec.: +32.85[1] mas/yr
Parallax (π)7.14 ± 0.42 mas[1]
Distance460 ± 30 ly
(140 ± 8 pc)
Absolute magnitude (MV)−1.06[4]
Orbit[6]
Period (P)605.8 d
Semi-major axis (a)6.5 mas[7]
Eccentricity (e)0.137±0.012
Inclination (i)136.0±5.1[7]°
Longitude of the node (Ω)325.5±2.8°
Periastron epoch (T)2,438,901.7±8.5 JD
Argument of periastron (ω)
(secondary)		311.8±5.2°
Semi-amplitude (K1)
(primary)		12.65±0.16 km/s
Details
4 UMi A
Radius28[8] R☉
Luminosity436.72[2] L☉
Surface gravity (log g)1.73±0.45[9] cgs
Temperature4,165±48[9] K
Metallicity [Fe/H]−0.19±0.11[9] dex
Other designations
4 UMi, BD+78° 478, FK5 524, HD 124547, HIP 69112, HR 5321, SAO 7958[10]
Database references
SIMBADdata

4 Ursae Minoris is a binary star[6] system in the northern circumpolar constellation Ursa Minor. It is faintly visible to the naked eye with an apparent visual magnitude of 4.80.[2] Based upon an annual parallax shift of 7.14±0.42 mas[1] as seen from Earth's orbit, it is located roughly 460 light years from the Sun. It is moving further away with a heliocentric radial velocity of +5.9 km/s.[5]

This is a single-lined spectroscopic binary star system with an orbital period of 1.66 years and an eccentricity of 0.14.[7][6] The primary is a red giant of spectral type K3-IIIb Fe-0.5,[3] a star that has used up its core hydrogen and is expanding. The suffix notation indicates the spectrum displays a mild underabundance of iron for a star of its type. It has expanded to around 28[8] times the Sun's radius and is radiating 437[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,165 K.[9]

References

  1. 1 2 3 4 5 6 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. 1 2 3 4 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.
  3. 1 2 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  4. 1 2 Ryon, Jenna; et al. (August 2009), "Comparing the Ca ii H and K Emission Lines in Red Giant Stars", Publications of the Astronomical Society of the Pacific, 121 (882): 842, arXiv:0907.3346, Bibcode:2009PASP..121..842R, doi:10.1086/605456, S2CID 17821279.
  5. 1 2 De Bruijne, J. H. J.; Eilers, A.-C. (2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: A61, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347.
  6. 1 2 3 Scarfe, C. D. (1971), "A Revised Orbit for 4 Ursae Minoris", Publications of the Astronomical Society of the Pacific, 83 (496): 807, Bibcode:1971PASP...83..807S, doi:10.1086/129218.
  7. 1 2 3 Ren, Shulin; Fu, Yanning (March 2013), "Hipparcos Photocentric Orbits of 72 Single-lined Spectroscopic Binaries", The Astronomical Journal, 145 (3): 7, Bibcode:2013AJ....145...81R, doi:10.1088/0004-6256/145/3/81, S2CID 120199240, 81.
  8. 1 2 Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  9. 1 2 3 4 Koleva, M.; Vazdekis, A. (February 2012), "Stellar population models in the UV. I. Characterisation of the New Generation Stellar Library", Astronomy & Astrophysics, 538: 13, arXiv:1111.5449, Bibcode:2012A&A...538A.143K, doi:10.1051/0004-6361/201118065, S2CID 53999614, A143.
  10. ↑ "4 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-04-02.
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