Gliese 229
Gliese 229 (also written as Gl 229 or GJ 229) is a binary system composed of a red dwarf and the first brown dwarf seen by astronomers, 18.8 light years away in the constellation Lepus. The primary component has 58% of the mass of the Sun, 69% of the Sun's radius, and a very low projected rotation velocity of 1 km/s at the stellar equator.
Gliese 229 A and B | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lepus |
| Right ascension | 06h 10m 34.61494s |
| Declination | −21° 51′ 52.6564″ |
| Apparent magnitude (V) | 8.14 |
| Characteristics | |
| Evolutionary stage | Main sequence / Brown dwarf |
| Spectral type | M1Ve / T7 |
| U−B color index | +1.222 |
| B−V color index | +1.478 |
| Variable type | Flare star |
| Astrometry | |
| Radial velocity (Rv) | 4.23±0.12 km/s |
| Proper motion (μ) | RA: −135.692(11) mas/yr Dec.: −719.178(17) mas/yr |
| Parallax (π) | 173.5740 ± 0.0170 mas |
| Distance | 18.791 ± 0.002 ly (5.7612 ± 0.0006 pc) |
| Absolute magnitude (MV) | 9.326 |
| Absolute bolometric magnitude (Mbol) | 7.96 |
| Orbit | |
| Companion | Gliese 229 B |
| Period (P) | 216.925+10.604 −10.352 yr |
| Semi-major axis (a) | 28.933+1.008 −1.000 AU |
| Eccentricity (e) | 0.853±0.002 |
| Inclination (i) | 5.497+0.153 −0.162° |
| Longitude of the node (Ω) | 145.946+0.306 −0.294° |
| Periastron epoch (T) | 2466912+97 −63 |
| Argument of periastron (ω) (secondary) | 358.285+0.836 −0.846° |
| Semi-amplitude (K1) (primary) | 0.081674+0.001688 −0.001680 km/s |
| Details | |
| A | |
| Mass | 0.579 M☉ |
| Radius | 0.69 R☉ |
| Luminosity (bolometric) | 0.0430 L☉ |
| Luminosity (visual, LV) | 0.0158 L☉ |
| Temperature | 3,700 K |
| Rotation | 27.3±0.2 d |
| Rotational velocity (v sin i) | 1 km/s |
| B | |
| Mass | 60.423+2.339 −2.379 MJup |
| Radius | 1.105±0.025 RJup |
| Luminosity (bolometric) | ~0.000011 L☉ |
| Surface gravity (log g) | 4.93+0.02 −0.03 cgs |
| Temperature | 869+5 −7 K |
| Other designations | |
| Database references | |
| SIMBAD | A |
| B | |
Gliese 229 Location of Gliese 229 in the constellation Lepus | |
The star is known to be a low activity flare star, which means it undergoes random increases in luminosity because of magnetic activity at the surface. The spectrum shows emission lines of calcium in the H and K bands. The emission of X-rays has been detected from the corona of this star. These may be caused by magnetic loops interacting with the gas of the star's outer atmosphere. No large-scale star spot activity has been detected.
The space velocity components of this star are U = +12, V = –11 and W = –12 km/s. The orbit of this star through the Milky Way galaxy has an eccentricity of 0.07 and an orbital inclination of 0.005.