Medusa Nebula (Abell 21 / Sh2-274) a closer look (DoubleStarPhotography)

Medusa Nebula (Abell 21 / Sh2-274) a closer look

In Greek mythology, Medusa was one of the three Gorgon sisters, monstrous creatures with living snakes in place of hair. The serpentine filaments formed by the nebula’s expending shells of gas are representative of Medusa's hair. Like other planetary nebulae, this planetary nebula was formed by an intermediate to low-mass red giant star that shed its outer layers in the late stage of its evolutionary cycle. The remnant stellar core is causing the expanding shells of ionized gas to brightly glow.

The stellar core of the Medusa Nebula is a PG 1159 star, and is in the process of transitioning from being a main sequence star into a hot white dwarf. PG 1159 stars are pre-degenerate stars with hydrogen-deficient atmospheres and surface temperatures between 75,000 K and 200,000 K. The Medusa nebula is considered to be an old planetary nebula, with an estimated age of ~8,800 years. (For reference - In the life of a star, the planetary nebula stage only lasts about 10,000 years, a very small fraction of the star's total life span.)

Imaging note: This is the companion shot to the wide field capture of this same object taken using dual scopes on the same nights and swapping Askar D1 & D2 filters between the scopes to capture similar amounts of Ha/Oiii/Sii for each image.

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Deep sky
Solar system
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Star trails
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Backyard
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Own remote observatory
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Professional, scientific grade data
Mix of multiple sources
Other
Unknown

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Status	Advanced success
Started	...
Astrometry.net job	9424330
PixInsight job	ELA4XILYQOGBAXR2YQT8QSR447FGNZEY
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	07h29m02s.864
RA (top/left)	07h30m23s.175
RA (top/right)	07h27m39s.627
RA (bottom/right)	07h27m42s.829
RA (bottom/left)	07h30m25s.906

Dec (center)	+13°15′00″.23
Dec (top/left)	+13°35′13″.41
Dec (top/right)	+13°34′29″.94
Dec (bottom/right)	+12°54′45″.84
Dec (bottom/left)	+12°55′29″.60

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