by APOD Robot » Fri Jun 12, 2015 4:05 am
The Medusa Nebula
Explanation: Braided, serpentine filaments of glowing gas suggest this nebula's popular name, The Medusa Nebula. Also known as Abell 21, this Medusa is an old
planetary nebula some 1,500 light-years away along the southern border of the constellation
Gemini. Like its
mythological namesake, the nebula is associated with a dramatic transformation. 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. An unrelated, bright, foreground star is near center in this
close-up, telescopic view, while the Medusa's transforming central star is actually the dimmer star below center and toward the right-hand part
of the frame. The Medusa Nebula is estimated to be over 4 light-years across.
[/b]
[url=http://apod.nasa.gov/apod/ap150612.html][img]http://apod.nasa.gov/apod/calendar/S_150612.jpg[/img] [size=150]The Medusa Nebula[/size][/url]
[b] Explanation: [/b] Braided, serpentine filaments of glowing gas suggest this nebula's popular name, The Medusa Nebula. Also known as Abell 21, this Medusa is an old [url=http://messier.seds.org/planetar.html]planetary nebula[/url] some 1,500 light-years away along the southern border of the constellation [url=http://www.eso.org/public/images/eso1520b/]Gemini[/url]. Like its [url=http://en.wikipedia.org/wiki/Medusa]mythological[/url] namesake, the nebula is associated with a dramatic transformation. The [url=http://www.noao.edu/jacoby/pn_gallery.html]planetary nebula[/url] phase represents a final stage in [url=http://casswww.ucsd.edu/public/tutorial/StevI.html]the evolution[/url] of low mass stars [url=http://www.astro.washington.edu/balick/WFPC2/]like the sun[/url], as they transform themselves from [url=http://en.wikipedia.org/wiki/Red_giant]red giants[/url] to hot white dwarf stars and in the process shrug off their outer layers. Ultraviolet [url=http://hyperphysics.phy-astr.gsu.edu/hbase/ems1.html]radiation[/url] from the hot star powers the nebular glow. An unrelated, bright, foreground star is near center in this [url=http://www.eso.org/public/news/eso1520/]close-up, telescopic view[/url], while the Medusa's transforming central star is actually the dimmer star below center and toward the right-hand part [url=http://apod.nasa.gov/apod/image/1506/eso1520aMedusaJ.jpg]of the frame[/url]. The Medusa Nebula is estimated to be over 4 light-years across.
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