11 Ursae Minoris

11 Ursae Minoris is a single[6] star located approximately 410 light years away[1] in the northern circumpolar constellation of Ursa Minor. The star is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.15.[2] It is moving closer to the Earth with a heliocentric radial velocity of −17.5 km/s.[1]

11 Ursae Minoris
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Minor
Right ascension 15h 17m 05.89154s[1]
Declination +71° 49′ 26.0375″[1]
Apparent magnitude (V) 5.15[2]
Characteristics
Spectral type K4 III[3]
Apparent magnitude (B) 6.664[2]
Apparent magnitude (J) 2.657[2]
Apparent magnitude (H) 1.931±0.192[2]
Apparent magnitude (K) 1.701±0.198[2]
B−V color index 1.514±0.004[2]
Astrometry
Radial velocity (Rv)−17.52±0.15[1] km/s
Proper motion (μ) RA: 3.430[1] mas/yr
Dec.: 10.113[1] mas/yr
Parallax (π)7.9539 ± 0.1249[1] mas
Distance410 ± 6 ly
(126 ± 2 pc)
Absolute magnitude (MV)–0.37[4]
Details[3]
Mass2.04±0.20 M☉
Radius28.20+0.71
−0.73 R☉
Luminosity258.8±17.7 L☉
Surface gravity (log g)1.60[4] cgs
Temperature4,358±59 K
Metallicity0.04 ± 0.04[4]
Age1.21±0.33 Gyr
Other designations
11 Ori, V1032 Ori, BD+72°678, FK5 1140, HD 136726, HIP 74793, HR 5714, SAO 8207, PPM 8870, GCRV 8864[5]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

This is an aging K-type giant star with a stellar classification of K4 III.[3] It is 1.2 billion years old with twice the mass of the Sun.[3] As a consequence of exhausting the hydrogen at its core, the star has expanded to 28 times the Sun's radius.[3] It is radiating 258 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,358 K.[3]

11 Ursae Minoris is sometimes named Pherkard or Pherkad Minor, the later name to distinguish it from Pherkad (Major) which is γ Ursae minoris. It has also been designated as γ1 Ursae minoris, in which case the brighter Pherkad is called γ2 Ursae minoris, but these names are rarely used.[7] 11 Ursae Minoris is the Flamsteed designation.

11 Ursae minoris has a detected planet discovered in August 2009.[4]

Planetary system

11 Ursae minoris b was discovered during a radial velocity survey of 62 K type Red giant stars using the 2m Alfred Jensch telescope of the Thuringian State Observatory in Germany.[4]

The 11 Ursae Minoris planetary system[4]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥10.50 ± 2.47 MJ 1.54 ± 0.07 516.22 ± 3.25 0.08 ± 0.03 — —

See also

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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. Baines, Ellyn K.; et al. (2018). "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer". The Astronomical Journal. 155 (1). 30. arXiv:1712.08109. Bibcode:2018AJ....155...30B. doi:10.3847/1538-3881/aa9d8b. S2CID 119427037.
  4. Döllinger, P.; et al. (2009). "Planetary companions around the K giant stars 11 Ursae Minoris and HD 32518". Astronomy and Astrophysics. 505 (3): 1311–1317. arXiv:0908.1753. Bibcode:2009A&A...505.1311D. doi:10.1051/0004-6361/200911702. S2CID 9686080.
  5. "11 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 September 2012.
  6. 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.
  7. Kostjuk, N. D. (2004). "VizieR Online Data Catalog: HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index (Kostjuk, 2002)". VizieR On-line Data Catalog: IV/27A. Originally Published in: Institute of Astronomy of Russian Academy of Sciences (2002). 4027. Bibcode:2004yCat.4027....0K.

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