Saturday, August 14, 2010

A Plethora of Planetaries

It is probably fair to say that when most stars die, they do it in style.  The bigger ones explode, leaving behind either black holes or extremely dense cores.  Some stars blast out shells of gas into interstellar space near the end of their lives.  The gas is illuminated by the star, and can take on a variety of shapes and colors.  These clouds of gas are called planetary nebulae.  They are called "planetary" because some resemble large planets.

Planetary nebulae are believed to only last a few thousand years, which is a short period of time when compared to the billions of years that their parent stars may have lived.  The Sun is expected to produce a planetary nebula toward the end of its life.

Below is my collection of planetary nebulae.  Some were primary targets, but others were simply in the field of view of another object.  I found a few of them by accident.

Charles Messier cataloged four planetary nebulae.  Each is visible as gray patches in small telescopes:

Messier 57, the Ring Nebula, in Lyra
Messier 76, the Little Dumbbell Nebula, in Perseus
The Little Dumbbell's big brother can be seen here.

Messier 97, the Owl Nebula, in Ursa Major
NGC 2438 is located in the constellation Puppis.  It is on the line of sight between us and Messier 46:

NGC 2438 in Puppis
I ran across several tiny planetary nebulae while examining my image of Messier 7.  The nebulae are the blue dots at the center of each image:

PK 355-4.1
PK 356-4.1
PK 356-5.1
Each of the above nebulae are in the Perek-Kohoutek catalog.  The numbers refer to their galactic coordinates.

NGC 7662, the Blue Snowball, is a popular target for amateur astronomers.  It is small, but intensely blue to the naked eye.  Here is an image that is composed of several short exposures:

NGC 7662, the Blue Snowball, in Andromeda

I ran across another planetary nebula while processing my image of Messier 34.  I got really excited because I couldn't find any references to it.  Was I the first to discover it?  "Surely not," I reasoned.  But amateur astronomers make new discoveries from time to time.  Finally, after quite a bit of searching on the Net, I found that it had already, in fact, been catalog by George Ogden Abell.  Here is planetary nebula Abell 4 in all of its not-discovered-by-Rory glory:

Abell 4 in Perseus

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