Medusa nebula, 24 inch telescope on Mt. Lemmon, AZ.
|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)||4 ly|
|Absolute magnitude (V)||7.68|
|Notable features||Very large & very low surface brightness|
|Designations||Sharpless 2-274, PK 205+14 1, Abel 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. Until the early 1970s, the nebula was thought to be a supernova remnant. 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.
- "MEDUSA – Planetary Nebula". Centre de Données astronomiques de Strasbourg. Retrieved 1 July 2010.
- Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; et al. (June 2003). "2MASS All Sky Catalog of point sources". The IRSA 2MASS All-Sky Point Source Catalog, NASA/IPAC Infrared Science Archive. Bibcode:2003tmc..book.....C.
- Nemiroff, R.; Bonnell, J., eds. (12 June 2010). "The Medusa Nebula". Astronomy Picture of the Day. NASA. Retrieved 1 July 2010.
- Lozinskaya, T. A. (June 1973). "Interferometry of the Medusa Nebula A21 (YM 29)". Soviet Astronomy. ADS. 16: 945. Bibcode:1973SvA....16..945L.