Medusa Nebula

Medusa Nebula
Emission nebula
Planetary nebula
	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)	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
	See also: Lists of nebulae

Coordinates: 07^h 29^m 02^s, +13° 14′ 15″

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.^[4] 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.^[4] As the nebula is so large, its surface brightness is very low, with surface magnitudes of between +15.99 and +25 reported.^{[citation needed]}

References[]

^ Jump up to: ^a ^b ^c ^d ^e "MEDUSA – Planetary Nebula". Centre de Données astronomiques de Strasbourg. Retrieved 1 July 2010.
^ Jump up to: ^a ^b 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.
^ Jump up to: ^a ^b Nemiroff, R.; Bonnell, J., eds. (12 June 2010). "The Medusa Nebula". Astronomy Picture of the Day. NASA. Retrieved 1 July 2010.
^ Jump up to: ^a ^b Lozinskaya, T. A. (June 1973). "Interferometry of the Medusa Nebula A21 (YM 29)". Soviet Astronomy. ADS. 16: 945. Bibcode:1973SvA....16..945L.