Medusa Nebula

This article is about a planetary nebula. For the Medusa Galaxy Merger, see NGC 4194.

Medusa Nebula
Medusa nebula, 24 inch telescope on Mt. Lemmon, AZ. Courtesy of Joseph D. Schulman
Observation data (Epoch J2000.0)
Right ascension	07h 29m 02.69s[1][2]
Declination	+13° 14′ 48.4″[1][2]
Distance	1,500 ly (460 pc)[3]
Apparent magnitude (V)	15.99[1]
Apparent dimensions (V)	4 ly[3]
Constellation	Gemini
Physical characteristics
Absolute magnitude (V)	7.68
Notable features	Very large & very low surface brightness
Other designations	Sharpless 2-274, PK 205+14 1, Abel 21 [1]
See also: Planetary nebula, Lists of nebulae

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

The Medusa Nebula is a large planetary nebula in the constellation of Gemini on the Canis Minor border. It also known as Abell 21 and Sharpless 274. It was originally discovered in 1955 by UCLA astronomer George O. Abell, who classified it as an old planetary nebula.^[4] The braided serpentine filaments of glowing gas suggests the serpent hair of Medusa found in ancient Greek mythology.

Until the early 1970s, the Medusa 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 big, its surface brightness is very low, with surface magnitudes of between +15.99 and +25 reported. Because of this most websites recommend at least an 8-inch (200 mm) telescope with an [O III] filter to find this object although probably possible to image with smaller apertures.^{[citation needed]}

References

1. ^ ^{a b c d} "MEDUSA -- Planetary Nebula". Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=Medusa+Nebula. Retrieved 2010-07-01. 
2. ^ ^{a b} Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A. et al. (2003 June). "2MASS All Sky Catalog of point sources". The IRSA 2MASS All-Sky Point Source Catalog, NASA/IPAC Infrared Science Archive.. Bibcode 2003tmc..book.....C. 
3. ^ ^{a b} Robert Nemiroff (MTU) & Jerry Bonnell (USRA) (12 June 2010). "The Medusa Nebula". Today's Astronomy Picture of the Day. http://antwrp.gsfc.nasa.gov/apod/ap100612.html. Retrieved 2010-07-01. 
4. ^ ^{a b} Lozinskaya, T. A. (1973, June). "Interferometry of the Medusa Nebula A21 (YM 29)" (PDF). Soviet Astronomy 16: p.945. Bibcode 1973SvA....16..945L. 

External links

• The Sharpless Catalog: Sharpless 274
• APOD picture: The Medusa Nebula
• Images of the Universe: PK 205+14.1 The Medusa Nebula in Gemini