GJ 1221
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Draco |
| Right ascension | 17h 48m 08.17s |
| Declination | +70° 52′ 35.3″ |
| Apparent magnitude (V) | 14.15 |
| Characteristics | |
| Spectral type | DQP9.0 |
| Apparent magnitude (B) | 14.55 |
| Apparent magnitude (V) | 14.15 |
| Apparent magnitude (R) | 13.5 |
| Apparent magnitude (I) | 13.1 |
| Apparent magnitude (J) | 12.709 ± 0.021 |
| Apparent magnitude (H) | 12.528 ± 0.023 |
| Apparent magnitude (K) | 12.507 ± 0.023 |
| Astrometry | |
| Proper motion (μ) |
RA: -1261 mas/yr Dec.: 1112 mas/yr |
| Parallax (π) | 164.7 ± 2.4mas |
| Distance | 19.8 ± 0.3 ly (6.07 ± 0.09 pc) |
| Absolute magnitude (MV) | 15.23 |
| Details | |
| Mass | 0.81 ± 0.01 M☉ |
| Radius | 0.00984 R☉ |
| Luminosity | 0.000085 L☉ |
| Surface gravity (log g) | 8.36 ± 0.02 cgs |
| Temperature | 5590 ± 90 K |
| Age | 5.69 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Coordinates: 
17h 48m 08.17s, +70° 52′ 35.3″
G 240-72 (or WD 1748+708, or LHS 455, or GJ 1221) is a nearby degenerate star (white dwarf) of spectral class DQP9.0, located in constellation Draco.
G 240-72 is the seventh closest white dwarf (after Sirius B, Procyon B, van Maanen's star, Gliese 440, 40 Eridani B and Stein 2051 B). Its trigonometric parallax is 0.1647 ± 0.0024 arcsec, corresponding to a distance 6.07 ± 0.09 pc, or 19.80+0.29
−0.28 ly.
G 240-72 has mass 0.81 Solar masses and surface gravity 108.36 (2.29 · 108) cm·s−2, or approximately 234 000 of Earth's, corresponding to a radius 6850 km, or 107% of Earth's.
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