11 Ursae Minoris

11 Ursae Minoris
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Ursa Minor
Right ascension	15h 17m 05.88946s
Declination	+71° 49′ 26.0473″
Apparent magnitude (V)	5.15
Characteristics
Spectral type	K4 III
Apparent magnitude (B)	6.664
Apparent magnitude (J)	2.657
Apparent magnitude (H)	1.931±0.192
Apparent magnitude (K)	1.701±0.198
B−V color index	1.514±0.004
Astrometry
Radial velocity (Rv)	−17.80±0.12 km/s
Proper motion (μ)	RA: +4.073 mas/yr ; Dec.: +9.477 mas/yr
Parallax (π)	7.9260±0.1249 mas
Distance	412 ± 6 ly ; (126 ± 2 pc)
Absolute magnitude (MV)	–0.37
Details
Mass	2.60+0.48; −0.44 M☉
Radius	29.14±0.45 R☉
Luminosity	250±6 L☉
Habitable zone inner limit	15.63±0.57 AU
Habitable zone outer limit	30.65±1.10 AU
Surface gravity (log g)	1.78±0.04 cgs
Temperature	4,253±25 K
Metallicity	−0.02±0.05
Age	639+507; −278 Myr
Other designations
	11 UMi, BD+72°678, FK5 1140, HD 136726, HIP 74793, HR 5714, SAO 8207, PPM 8870, GCRV 8864
Database references
SIMBAD	data
Exoplanet Archive	data

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 M_J, 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 $M$ _J	1.54 ± 0.07	516.22 ± 3.25	0.08 ± 0.03	—	—

References

^ ^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.
^ ^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.
^ ^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.
^ ^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.
^ ^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. arXiv:2506.02934. doi:10.3847/1538-3881/ad9bb1. ISSN 1538-3881.
^ ^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 T_eff and log ɡ of the third version (Corrigendum)". Astronomy & Astrophysics. 693: C3. arXiv:2310.11302. doi:10.1051/0004-6361/202453050e. ISSN 0004-6361.
^ "11 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 September 2012.
^ 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.
^ 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.

External links

Jean Schneider (2011). "Notes for star 11 UMi". Extrasolar Planets Encyclopaedia. Archived from the original on August 19, 2009. Retrieved 30 September 2011.

[GaiaDR3-1] ^ ^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.

[Anderson2012-2] ^ ^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.

[Baines2018-3] 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.

[Döllinger2009-4] 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.

[Baines2025-5] ^ ^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. arXiv:2506.02934. doi:10.3847/1538-3881/ad9bb1. ISSN 1538-3881.

[Soubiran2024-6] 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 T_eff and log ɡ of the third version (Corrigendum)". Astronomy & Astrophysics. 693: C3. arXiv:2310.11302. doi:10.1051/0004-6361/202453050e. ISSN 0004-6361.

[Simbad-7] "11 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 September 2012.

[Eggleton2008-8] 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.

[xref-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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Observation data Epoch J2000.0 Equinox J2000.0
Constellation	Ursa Minor
Right ascension	15^h 17^m 05.88946^s^[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 (R_v)	−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]
Distance	412 ± 6 ly (126 ± 2 pc)
Absolute magnitude (M_V)	–0.37^[4]

Details

Mass	2.60+0.48 −0.44^[5] `M`_☉
Radius	29.14±0.45^[5] `R`_☉
Luminosity	250±6^[6] `L`_☉
Habitable zone inner limit	15.63±0.57^[5] AU
Habitable zone outer limit	30.65±1.10^[5] AU
Surface gravity (log g)	1.78±0.04^[6] cgs
Temperature	4,253±25^[6] K
Metallicity	−0.02±0.05^[6]
Age	639+507 −278^[5] Myr

Other designations
11 UMi, BD+72°678, FK5 1140, HD 136726, HIP 74793, HR 5714, SAO 8207, PPM 8870, GCRV 8864^[7]
Database references
SIMBAD	data
Exoplanet Archive	data

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