11 Ursae Minoris

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]

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]
Distance	412 ± 6 ly (126 ± 2 pc)
Absolute magnitude (MV)	–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

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 MJ	1.54 ± 0.07	516.22 ± 3.25	0.08 ± 0.03	—	—