A B E L L P l a n e t a r y N e b u l a
Planetary Nebulae are clouds of interstellar matter, thin but widespread shells of gas and dust. They mark where a star is slowly dying, and is ejecting material into interstellar space during its later life stages. On cosmic timescales, planetary nebulae undergo rapid changes and have only comparatively short lifetimes, so that those we observe are all relatively young objects. Planetary nebulae usually have only a few thousand years before they fade and spread their matter into the interstellar environment.
American astrophysicist George Abell, (1927 - 1983), graduated from from the California Institute of Technology.
(B.S. in 1951, M.S. in 1952, and Ph.D. in 1957.)
Using the Palomar 48-inch Schmidt telescope, Abell compiled a catalog of very old, faint planetary nebula, which was first published in 1955 titled "Properties of Some Old Planetary Nebula", and expanded several times with the final version in 1966. Abell's catalog is recognized as an excellent compilation of faint, challenging planetaries for the observer with access to large telescopes and dark skies. For the most part, due to being very old, large, and having a very low surface brightness, they can be difficult to observe. O-III filters can be a big help, allowing the nebula to 'pop' from the dimmed field. (though sometimes it can actually make the nebula harder to see).
Here's a few interesting links:
Steve Gottlieb's Adventures - Planetary Nebula:
Uwe Glahn (visual descriptions and images)
Reiner Vogel (downlod observing guide)
Below is my personal observation list of the 'Abell Planetary Nebulas'.
I currently have 10 out of 82 objects visible from my Pittsburgh, PA latitude of around +40.
All of my images were taken using a StellaCam-3 peltier-cooled deepsky video camera. Each image has minimal processing applied to it: brightness/contrast adjusted, image rotated to match that of Alvin Huey's book, and resized to have the same general field size across images. The 'Negative' image is a little more heavily processed to help bring out the nebula.
Most of these are very faint, even with long exposures and using a O-III filter.
|2||Smooth disk (a, brighter toward center; b, uniform brightness; c, traces of a ring structure)|
|3||Irregular disk (a, very irregular brightness distribution; b, traces of ring structure)|
|5||Irregular form, similar to a diffuse nebula|
Hope you enjoyed the visit. Come again soon!
Larry McHenry, Pittsburgh, PA. USA