Celestial hemisphere:  Northern  ·  Constellation: Cancer (Cnc)  ·  Contains:  PK208+33.1
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Abell 30 | One of Only Four Known Reborn Planetary Nebulae, Kevin Morefield
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Abell 30 | One of Only Four Known Reborn Planetary Nebulae

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Abell 30 | One of Only Four Known Reborn Planetary Nebulae, Kevin Morefield
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Abell 30 | One of Only Four Known Reborn Planetary Nebulae

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Description

Abell 30 is not unique but it sure is close.  Around 12,500 years ago this star depleted its hydrogen and began ejecting its outer layers into a planetary nebula.  From this event we see a reddish hydrogen spherical shell with teal blue OIII seeming to float on the surface.  This is pretty standard stuff.  But 850 years ago nuclear chain reactions rekindled and began a second planetary neblue inside the old shell.  These are the bright knots we see surrounding the central star.  What I cannot find any information on is what, exactly, is the small red star just next to the central star in the nebula.  It may be foreground or background or maybe related to the object, but I can't find any info on that.

This process of "re-brith" is also referred to as a death rattle.    Rebirth is only known in four cases, one of which is Abell 78.  Part of what makes this rare is likely the brief time it occurs during the life (or death) of a star.  If you assume that the star has been around for maybe 4 billion years, the Planetary stage has lasted .00003% of the star's life.  And this second nebula only .000002%.  Due to the rapid expansion of these gasses they will become so diffuse that we will no longer see them in a short period of time - at least relative to the life of the star.

The Harvard/Chandra site has a concise description of what's happening here:  https://chandra.harvard.edu/photo/2012/a30/
Here's the short description:

After having steadily produced energy for several billion years through the nuclear fusion of hydrogen into helium in its central region, or core, the star undergoes a series of energy crises related to the depletion of hydrogen and subsequent contraction of the core. These crises culminate in the star expanding a hundred-fold to become a red giant.Eventually the outer envelope of the red giant is ejected and moves away from the star at a relatively sedate speed of less than 100,000 miles per hour. The star meanwhile is transformed from a cool giant into a hot, compact star that produces intense ultraviolet (UV) radiation and a fast wind of particles moving at about 6 million miles per hour. The interaction of the UV radiation and the fast wind with the ejected red giant envelope creates the planetary nebula, shown by the large spherical shell in the bigger image.In rare cases, nuclear fusion reactions in the region surrounding the star's core heat the outer envelope of the star so much that it temporarily becomes a red giant again. The sequence of events — envelope ejection followed by a fast stellar wind — is repeated on a much faster scale than before, and a small-scale planetary nebula is created inside the original one. In a sense, the planetary nebula is reborn.

Processing Notes

The Ha and OIII data were combined into an HOO NB master.  RGB was used for the stars and background.  The two masters were combined with a mask in Photoshop.  Noise reduction was done with Adobe Camera Raw and with Topaz AI.  The Topaz work was done only on the narrowband data and care was taken that no false structures were created.  

The Ha data shows a very evenly illuminated globe with little detail other than the brightest of the inner knots.  The OIII shows brighter and darker areas on the older, outer shell and the interesting "octopus" like inner arms are only represented in OIII.  The brief RGB data does in fact present the outer shell in a pleasing blue.  It might be interesting to shoot a long set of data on this in broadband.

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    Abell 30 | One of Only Four Known Reborn Planetary Nebulae, Kevin Morefield
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Description: Crop and further noise reduction

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Abell 30 | One of Only Four Known Reborn Planetary Nebulae, Kevin Morefield