11 Ursae Minoris
Star in the constellation Ursa Minor
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11 Ursae Minoris, formally named Pherkad Minor, 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 â17.8 km/s.[1]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ursa Minor |
| Right ascension | 15h 17m 05.88946s[1] |
| Declination | +71° 49â² 26.0473â³[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] |
| BâV color index | 1.514±0.004[2] |
| Astrometry | |
| Radial velocity (Rv) | â17.80±0.12[1] km/s |
| Proper motion (μ) | RA: +4.073 mas/yr[1] Dec.: +9.477 mas/yr[1] |
| Parallax (Ï) | 7.9260±0.1249 mas[1] |
| Distance | 412 ± 6 ly (126 ± 2 pc) |
| Absolute magnitude (MV) | â0.37[4] |
| Details | |
| Mass | 2.60+0.48 â0.44[5] Mâ |
| Radius | 29.14±0.45[5] Râ |
| Luminosity | 250±6[6] Lâ |
| 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 | â0.02±0.05[6] |
| Age | 639+507 â278[5] Myr |
| Other designations | |
| Pherkad Minor, 11 UMi, BD+72°678, HD 136726, HIP 74793, HR 5714, SAO 8207, PPM 8870, GCRV 8864[7] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Nomenclature
11 Ursae Minoris is the star's Flamsteed designation. It is sometimes named Pherkad Minor (alternatively spelled Pherkard), in reference to the brighter nearby star Pherkad (Major) which is γ Ursae Minoris.[9] The name originated with Giuseppe Piazzi.[10] 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] The IAU Working Group on Star Names approved the name Pherkad Minor for 11 Ursae Minoris on 22 March 2026 and it is now so entered in the IAU Catalog of Star Names.[10]
Stellar properties
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]
Planetary system
11 Ursae Minoris has a detected planet discovered in August 2009.[4] 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 likely make 11 Ursae Minoris b a low-mass brown dwarf.[5]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | â¥14.15±1.23 MJ | 1.54 ± 0.07 | 516.22 ± 3.25 | 0.08 ± 0.03 | â | â |