11 Ursae Minoris

11 Ursae Minoris
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Minor
Right ascension 15h 17m 05.88946s[1]
Declination +71° 49′ 26.0473″[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)−17.80±0.12[1] km/s
Proper motion (μ) RA: +4.073 mas/yr[1]
Dec.: +9.477 mas/yr[1]
Parallax (π)7.9260 ± 0.1249 mas[1]
Distance412 ± 6 ly
(126 ± 2 pc)
Absolute magnitude (MV)–0.37[4]
Details
Mass2.60+0.48
−0.44[5] M☉
Radius29.14±0.45[5] R☉
Luminosity250±6[6] L☉
Habitable zone inner limit15.63±0.57[5] AU
Habitable zone outer limit30.65±1.10[5] AU
Surface gravity (log g)1.78±0.04[6] cgs
Temperature4,253±25[6] K
Metallicity−0.02±0.05[6]
Age639+507
−278[5] Gyr
Other designations
11 UMi, BD+72°678, FK5 1140, HD 136726, HIP 74793, HR 5714, SAO 8207, PPM 8870, GCRV 8864[7]
Database references
SIMBADdata
Exoplanet Archivedata

11 Ursae Minoris is a single[8] 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 −17.8 km/s.[1]

This is an aging K-type giant star with a stellar classification of K4 III.[3] It is 600 million years old with twice the mass of the Sun. As a consequence of exhausting the hydrogen at its core, the star has expanded to 29 times the Sun's radius.[5] It is radiating 250 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,253 K.[6]

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.[9] 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]

A newer mass measurement of the host star implies a larger planetary mass of 14.15±1.23 MJ, which would make 11 Ursae Minoris b a low-mass brown dwarf.[5]

The 11 Ursae Minoris planetary system[4]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥14.15±1.23 MJ 1.54 ± 0.07 516.22 ± 3.25 0.08 ± 0.03 — —

References

  1. ^ a b c d e f g Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c d e f g 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. ^ a b 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. ^ a b c d 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. ^ a b c d e f g Baines, Ellyn K.; Jones, Jeremy; Clark, James H.; Schmitt, Henrique R.; Stone, Jordan M. (January 2025). "Eighteen Exoplanet Host Stars from the NPOI Data Archive". The Astronomical Journal. 169 (2): 83. doi:10.3847/1538-3881/ad9bb1. ISSN 1538-3881.
  6. ^ a b c d e Soubiran, C.; Creevey, O.; Lagarde, N.; Brouillet, N.; Jofré, P.; Casamiquela, L.; Heiter, U.; Aguilera–Gómez, C.; Vitali, S.; Worley, C.; de Brito Silva, D. (February 2024). "Gaia FGK benchmark stars: Fundamental Teff and log ɡ of the third version (Corrigendum)". Astronomy & Astrophysics. 693: C3. arXiv:2310.11302. doi:10.1051/0004-6361/202453050e. ISSN 0004-6361.
  7. ^ "11 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 September 2012.
  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, S2CID 14878976.
  9. ^ 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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