Sh 2-68
Planetary nebula
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Sh 2-68 (also known as Flaming Skull Nebula) is a planetary nebula located in the constellation Serpens. It is the remnant of a low to intermediate mass star that has shed its outer layers, leaving behind a glowing shell of ionized gas illuminated by its central white dwarf star. Estimated to be 30,000 to 45,000 years old, Sh 2-68 is notable for its interaction with the surrounding interstellar medium (ISM), which has stalled the nebula's expansion and created an extended tail structure, giving it a distinctive asymmetrical appearance.[3][4][5]
| Nebula | |
|---|---|
Image of Sh 2-68 Nebula | |
| Observation data: epoch | |
| Right ascension | 18h 24m 58.43s[1] |
| Declination | +00° 51′ 36.0″[1] |
| Distance | 350 pc |
| Constellation | Serpens |
| Physical characteristics | |
| Dimensions | 8'[2] |
| Designations | Sh 2-68, LBN 93, PN G030.6+06.2[1] |
It has a proper motion of 53.2 +/- 5.5 mas yr-1, the largest value for a planetary nebula ever found.[6]
Central star
The central star of Sh 2-68 is a hot white dwarf designated WD 1822+008 with a spectral type DAOZ.6, indicating strong absorption lines from hydrogen and helium in a hot atmosphere. The star appears as a blue point source offset from the nebula's center, embedded in the oxygen-rich core.[7][1][4][8]
