G 99-47
G 99-47 (V1201 Orionis) is a nearby degenerate star (white dwarf) of spectral class DAP8 (DAP8.9, or DAP8.7), the single known component of the system, located in the constellation Orion. G 99-47 is probably the tenth closest white dwarf, followed by Gliese 293, Gliese 518 and Gliese 915.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 56m 25.47s |
| Declination | +05° 21′ 48.6″ |
| Apparent magnitude (V) | 14.105 |
| Characteristics | |
| Spectral type | DAP8.9 |
| Apparent magnitude (B) | 14.69 |
| Apparent magnitude (V) | 14.10 |
| Apparent magnitude (R) | 14.0 |
| Apparent magnitude (I) | 13.6 |
| Apparent magnitude (J) | 12.930 ± 0.022 |
| Apparent magnitude (H) | 12.720 ± 0.025 |
| Apparent magnitude (K) | 12.653 ± 0.024 |
| Astrometry | |
| Proper motion (μ) | RA: -444.685 mas/yr Dec.: -925.140 mas/yr |
| Parallax (π) | 123.1989 ± 0.0170 mas |
| Distance | 26.474 ± 0.004 ly (8.117 ± 0.001 pc) |
| Absolute magnitude (MV) | 14.59 |
| Details | |
| Mass | 0.71 ± 0.03 M☉ |
| Radius | 0.011 R☉ |
| Surface gravity (log g) | 8.20 ± 0.05 cgs |
| Temperature | 5790 ± 110 K |
| Age | 3.97 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The mass of G 99-47 is 0.71±0.03 Solar masses; its surface gravity is 108.20 ± 0.05 (1.58 · 108) cm·s−2, or approximately 162 000 of Earth's, corresponding to a radius 7711 km, or 121% of Earth's. Its temperature is 5790 ± 110 K, almost like the Sun's; its cooling age, i. e. age as degenerate star (not including lifetime as main sequence star and as giant star) is 3.97 Gyr. Due almost equal to the Sun's temperature, GJ 1087 should appear almost the same white color as the Sun. The white dwarf has a strong magnetic field, with measured vertical component near surface equal to 560 T.