Medusa Nebula
| Emission nebula | |
|---|---|
| Planetary nebula | |
Medusa nebula, Mayall Telescope | |
| Observation data: J2000.0 epoch | |
| Right ascension | 07h 29m 02.69s |
| Declination | +13° 14′ 48.4″ |
| Distance | 1,500 ly (460 pc) ly |
| Apparent magnitude (V) | 15.99 |
| Apparent dimensions (V) | 10.25 x 10.25 arcmin |
| Constellation | Gemini |
| Physical characteristics | |
| Radius | 4 ly |
| Absolute magnitude (V) | 7.68 |
| Notable features | Very large & very low surface brightness |
| Designations | Sharpless 2-274, PK 205+14 1, Abell 21 |
The Medusa Nebula is a planetary nebula in the constellation of Gemini. It is also known as Abell 21 and Sharpless 2-274. It was originally discovered in 1955 by University of California, Los Angeles astronomer George O. Abell, who classified it as an old planetary nebula. With the computation of expansion velocities and the thermal character of the radio emission, Soviet astronomers in 1971 concluded that it was most likely a planetary nebula. As the nebula is so large, its surface brightness is very low, with surface magnitudes of between +15.99 and +25 reported.
The central star of the planetary nebula is an PG 1159 star.