HIP 57050
HIP 57050, or GJ 1148, is a faint star with two orbiting exoplanets in the northern constellation of Ursa Major. Other designations for this star include LHS 2443, G 122-40, and Ross 1003. From a distance of 36 light years based on parallax measurements, it is drifting closer to the Sun with a radial velocity of -9 km/s. This is a faint star with an absolute magnitude of 11.64. At the distance of HIP 57050, the apparent visual magnitude is 11.86, which is much too faint to be seen with the naked eye. HD 164595 has a high proper motion, traversing the celestial sphere at an angular rate of 0.577″ yr−1.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 11h 41m 44.63584s |
| Declination | +42° 45′ 07.1021″ |
| Apparent magnitude (V) | 11.86 |
| Characteristics | |
| Spectral type | M4.0V |
| U−B color index | +1.52 |
| B−V color index | +1.503±0.012 |
| V−R color index | +1.19 |
| Astrometry | |
| Radial velocity (Rv) | −8.99±0.0014 km/s |
| Proper motion (μ) | RA: −575.528(26) mas/yr Dec.: −89.799(25) mas/yr |
| Parallax (π) | 90.6896 ± 0.0258 mas |
| Distance | 35.96 ± 0.01 ly (11.027 ± 0.003 pc) |
| Absolute magnitude (MV) | 11.64 |
| Details | |
| Mass | 0.357±0.013 M☉ |
| Radius | 0.4 R☉ |
| Luminosity | 0.01486 L☉ |
| Surface gravity (log g) | 4.67 cgs |
| Temperature | 3,236±18 K |
| Metallicity [Fe/H] | 0.32±0.06 dex |
| Rotation | 71.5±5.1 d |
| Rotational velocity (v sin i) | 2.0 km/s |
| Age | 4.44±0.016 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
The spectrum of HIP 57050 matches a small M-type main-sequence star, a red dwarf, with a stellar classification of M4.0V. HIP 57050 has a metallicity twice that of the Sun and is among the highest in the immediate solar neighborhood. It has a quiet chromosphere that displays little magnetic activity. A minimal level of amplitude variation from rotation suggests the star may be viewed from nearly pole-on. This star has 36% of the Sun's mass and 40% of the radius of the Sun. It is radiating just 1.5% of the luminosity of the Sun from its photosphere at an effective temperature of 3,236 K.