| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major[1] |
| Right ascension | 11h 44m 40.9643s[2] |
| Declination | +30° 57′ 33.451″[2] |
| Apparent magnitude (V) | 8.96[3] |
| Characteristics | |
| Spectral type | K5 V[3] |
| U−Bcolor index | +1.06[4] |
| B−Vcolor index | +1.111±0.016[1] |
| Astrometry | |
| Radial velocity (Rv) | +29.76±0.35[2] km/s |
| Proper motion (μ) | RA: −27.069±0.081[2]mas/yr Dec.: −381.708±0.079[2]mas/yr |
| Parallax (π) | 38.6381±0.0499 mas[2] |
| Distance | 84.4 ± 0.1 ly (25.88 ± 0.03 pc) |
| Absolute magnitude (MV) | 6.89[3] |
| Details[3] | |
| Mass | 0.73±0.05 M☉ |
| Radius | 0.68±0.03 R☉ |
| Luminosity | 0.19±0.01 L☉ |
| Surface gravity (log g) | 4.71±0.1 cgs |
| Temperature | 4,640±100 K |
| Metallicity[Fe/H] | +0.09±0.05 dex |
| Rotation | 45 d |
| Rotational velocity (v sin i) | 0.5±0.5 km/s |
| Age | 7.87±5 Gyr |
| Other designations | |
| BD+31°2290,Gaia DR2 4021079911593673600,GJ 439,HIP 57274,SAO 62684,LTT 13227,2MASS J11444095+3057339[5] | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
HIP 57274 is astar in the northerncircumpolar constellation ofUrsa Major with a system of three planets.[3] It is invisible to the naked eye, having anapparent visual magnitude of 8.96.[3] The distance to this system is 84.4 light years based onstellar parallax, and it is drifting further away with aradial velocity of +30 km/s.[2] The star has a relatively high rate ofproper motion, traversing thecelestial sphere at the rate of0.382 arcsecond/year.[6]
This is an ordinaryK-type main-sequence star with astellar classification of K5V.[3] It appears to be older than the Sun with an age of roughly eight billion years and is spinning slowly with aprojected rotational velocity of under 1 km/s. The star has 73% of themass of the Sun and 68% of theSun's radius. The abundance of elements heavier than helium is about the same or slightly higher than in the Sun. The star is radiating just 19% of theluminosity of the Sun from itsphotosphere at aneffective temperature of 4,640 K.
The three exoplanets orbiting HIP 57274 were discovered by theradial velocity method in 2011, all of them having mass significantly greater than the Earth.[3] A 2014 search forplanetary transits was unsuccessful.[7] The planetary orbits are possibly highly variable, being strongly affected bymean motion resonances.[8] The most stable region for a hypothetical super-earth within the star'shabitable zone would be an orbit inside 0.37–0.56 AU from the host star.[8]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥11.6±1.3 M🜨 | 0.0713±0.00163 | 8.1352±0.004 | 0.187±0.10 | — | — |
| c | ≥0.41±0.01 MJ | 0.1778±0.0041 | 32.03±0.02 | 0.05±0.02 | — | — |
| d | ≥0.53±0.03 MJ | 1.007±0.027 | 431.7±8.5 | 0.27±0.05 | — | — |
