G 99-47
Star in the constellation Orion
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G 99-47 (V1201 Orionis) is a nearby degenerate star (white dwarf) of spectral class DAP8 (DAP8.9,[4] or DAP8.7[3]), the single known component of the system, located in the constellation Orion. G 99-47 is the 10th-closest known white dwarf, the next closest after LP 658-2 and GJ 3991 B.[7]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 56m 25.45999s[2] |
| Declination | +05° 21′ 48.4432″[2] |
| Apparent magnitude (V) | 14.105[3] |
| Characteristics | |
| Spectral type | DAP8.9[4] |
| Apparent magnitude (B) | 14.69[5] |
| Apparent magnitude (V) | 14.10[5] |
| Apparent magnitude (R) | 14.0[5] |
| Apparent magnitude (I) | 13.6[5] |
| Apparent magnitude (J) | 12.930 ± 0.022[5] |
| Apparent magnitude (H) | 12.720 ± 0.025[5] |
| Apparent magnitude (K) | 12.653 ± 0.024[5] |
| Astrometry | |
| Radial velocity (Rv) | −414.02±10.41[2] km/s |
| Proper motion (μ) | RA: -444.685 mas/yr[2] Dec.: -925.140 mas/yr[2] |
| Parallax (π) | 123.1989±0.0170 mas[2] |
| Distance | 26.474 ± 0.004 ly (8.117 ± 0.001 pc) |
| Absolute magnitude (MV) | 14.59[3][6][note 1] |
| Details | |
| Mass | 0.71 ± 0.03[3] M☉ |
| Radius | 0.011[3][note 2] R☉ |
| Surface gravity (log g) | 8.20 ± 0.05[3] cgs |
| Temperature | 5790 ± 110[3] K |
| Age | 3.97[4][note 3] Gyr |
| Other designations | |
| V1201 Ori, GJ 1087, EGGR 290, G 99-47, G 102-40, G 106-15, LHS 212, LTT 17891, NLTT 15834, WD 0553+053, 2MASS J05562547+0521486, USNO-B1.0 0953-00073703[5] | |
| Database references | |
| SIMBAD | data |
The mass of G 99-47 is 0.71±0.03 Solar masses;[3] its surface gravity is 108.20 ± 0.05 (1.58 · 108) cm·s−2,[3] or approximately 162 000 of Earth's, corresponding to a radius 7711 km, or 121% of Earth's. Its temperature is 5790 ± 110 K,[3] 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.[4] 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.[8]
