WD J2356−209
White dwarf star in the constellation Cetus
From Wikipedia, the free encyclopedia
WD J2356−209 (also known as WD 2354−211)[8] is a white dwarf star located 65 pc (212 ly) away from the Earth.[9] It is a very faint white dwarf, with an apparent visual magnitude of 21.03.[10] Its visible spectrum is dominated by a broad absorption feature[5] that has been attributed to pressure-broadened sodium D lines.[11] The presence of this sodium absorption feature and the detection of spectral lines from other heavy elements (calcium, iron and magnesium) indicate that the photosphere of WD J2356−209 has been polluted by a recent rocky debris accretion episode. A detailed analysis of the spectrum of WD J2356−209 shows that the accreted planetesimal was abnormally sodium-rich, containing up to ten times more sodium than calcium.[6] With an effective temperature of 4040 K, WD J2356−209 was the coolest metal-polluted white dwarf observed at the time (and also the oldest, with a white dwarf cooling age of about 8 Gyr).[6]
| Observation data Epoch J2000.0 (ICRS) Equinox ICRS | |
|---|---|
| Constellation | Cetus[1] |
| Right ascension | 23h 56m 45.096s[2] |
| Declination | −20° 54′ 49.94″[2] |
| Apparent magnitude (V) | 20.7[3] |
| Characteristics | |
| Evolutionary stage | white dwarf[4] |
| Spectral type | DC[5] or DZ[6] |
| Astrometry | |
| Proper motion (μ) | RA: −295.490[2] mas/yr Dec.: −239.372[2] mas/yr |
| Parallax (π) | 15.2759±0.5810 mas[2] |
| Distance | 214 ± 8 ly (65 ± 2 pc) |
| Details | |
| Mass | 0.56[7] M☉ |
| Surface gravity (log g) | 8.26±0.15[6] cgs |
| Temperature | 4,310±190[6] K |
| Age | 8.0±0.8[6] Gyr |
| Database references | |
| SIMBAD | data |
See also
- List of exoplanets and planetary debris around white dwarfs
- WD J2147–4035 is the coldest and oldest metal-polluted white dwarf (as of September 2024)[4]
- WD 2317+1830 is another cold metal-polluted white dwarf
