Abell 21, Medusa Nebula (Jeff Weiss)

Celestial hemisphere: Northern · Constellation: Gemini (Gem) · Contains: PK205+14.1 · Sh2-274

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Abell 21, Medusa Nebula

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Abell 21, Medusa Nebula

Abell 21, the Medusa Nebula, is a planetary nebula in Gemini. It is also known as PK205+14.1 and Sharpless 2-274. It has a large apparent size 10.3 arc minutes across with low surface magnitudes (+16 to +35). The actual size is estimated to be 4 light years across at 1500 light years distance. It was originally discovered in 1955 by astronomer George O. Abell, who classified it as an old planetary nebula. Astronomers in 1971 verified it was a planetary nebula and not a supernova remnant as some suspected. The planetary nebula phase represents a final stage in the evolution of low mass stars like the sun, as they transform themselves from red giants to hot white dwarf stars and in the process shrug off their outer layers. Ultraviolet radiation from the hot star powers the nebular glow. The progenitor star is the small bluish star slightly below center [various sources] . North is up.

This 17.7 hr HaLRGB image uses DeepSkyWest data collected in New Mexico at my targeting suggestion between 2/17/21 and 3/19/21. Processing was finished 3/29/21. It could have used more Ha and some O3 data but maybe next year.

Original
F
Final
G

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Status	Advanced success
Started	...
Astrometry.net job	5544592
PixInsight job	SKNOQHD9CKKBXO957U2GBIMKRSEQZZIS
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	07h28m53s.138
RA (top/left)	07h27m51s.307
RA (top/right)	07h29m52s.891
RA (bottom/right)	07h29m54s.907
RA (bottom/left)	07h27m53s.536

Dec (center)	+13°16′21″.19
Dec (top/left)	+13°25′47″.55
Dec (top/right)	+13°26′34″.18
Dec (bottom/right)	+13°06′52″.73
Dec (bottom/left)	+13°06′06″.10

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Abell 21, Medusa Nebula

Abell 21, Medusa Nebula

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Abell 21, Medusa Nebula

Abell 21, Medusa Nebula

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