47 Ursae Majoris
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 10h 59m 27.9728s |
| Declination | +40° 25′ 48.921″ |
| Apparent magnitude (V) | +5.03 |
| Characteristics | |
| Spectral type | G1V |
| U−B color index | 0.13 |
| B−V color index | 0.61 |
| Astrometry | |
| Radial velocity (Rv) | 11.24(12) km/s |
| Proper motion (μ) | RA: −316.850(97) mas/yr Dec.: 55.180(118) mas/yr |
| Parallax (π) | 72.0070±0.0974 mas |
| Distance | 45.30 ± 0.06 ly (13.89 ± 0.02 pc) |
| Absolute magnitude (MV) | 4.41 |
| Details | |
| Mass | 1.02±0.06 M☉ |
| Radius | 1.23±0.02 R☉ |
| Luminosity | 1.62+0.07 −0.08 L☉ |
| Surface gravity (log g) | 4.30±0.02 cgs |
| Temperature | 5,880±10 K |
| Metallicity | +0.02±0.01 |
| Rotational velocity (v sin i) | 2.80 km/s |
| Age | 8.1+2.4 −3.1 Gyr |
| Other designations | |
| Chalawan, BD+41°2147, FK5 1282, GC 15087, GCTP 2556.00, Gliese 407, HD 95128, HIP 53721, HR 4277, LTT 12934, SAO 43557 | |
| Database references | |
| SIMBAD | The star |
| planet b | |
| planet c | |
| planet d | |
| Exoplanet Archive | data |
| ARICNS | data |
47 Ursae Majoris (abbreviated 47 UMa), formally named Chalawan /ˈtʃɑːləwən/, is a yellow dwarf star approximately 45.3 light-years from Earth in the constellation of Ursa Major. As of 2011, three extrasolar planets (designated 47 Ursae Majoris b, c and d; the first two later named Taphao Thong and Taphao Kaew) are known to orbit the star.
The star is located fairly close to the Solar System: according to astrometric measurements made by the Gaia space observatory, it exhibits a parallax of 72.0070 milliarcseconds, corresponding to a distance of 45.30 light-years. With an apparent magnitude of +5.03, it is visible to the naked eye and its absolute magnitude of +4.29 implies a visual luminosity around 60% greater than the Sun. A solar analog, with a spectral type of G1V, it has a similar mass to that of the Sun but is slightly hotter at around 5,880 K. and slightly more metal-rich with around 105% of the solar abundance of iron.
Like the Sun, 47 Ursae Majoris is on the main sequence, converting hydrogen to helium in its core by nuclear fusion. Based on its chromospheric activity, the star may be around six billion years old, though evolutionary models suggest an older age of around 8.7 billion years. Other studies have yielded estimates of 4.4 and 7 billion years for the star. The low level of magnetic activity makes it a Maunder Minimum candidate star.