This poster shows the complete Abell PN Catalogue. This catalogue was created in 1966 by Dr. George Abell from new objects discovered on the photographs taken for the Palomar Sky Survey.

The catalogue consists of 86 total entries, although only 79 of these entries are truly planetary nebulae. The 7 objects which have been confirmed NOT to be planetary nebulae are:

1.  #11 (reflection nebula)
2.  #17 (red plate flaw)
3.  #32 (red plate flaw)
4.  #35 (stromgren sphere)
5.  #64 (galaxy CGCG 397-5)
6.  #76 (ring galaxy PGC 85185)
7.  #85 (supernova remnant CTB 1)

I did not include these objects in the poster.  

I think it is interesting to examine the PNe on the poster, observing commonalities and differences.  Some of the definition of PN types below is described in my PN Morphology poster here.  The descriptions below are simply my observations and are not based on confirming technical data or expert analysis:

Composition (Color):  The catalogue is fairly evenly split into 4 different composition types - OIII (blue), HII (red), Balanced (grey), and Mixed (OIII with a HII rim).  Note that none of the objects are Mixed in the opposite sense (HII with an OIII rim). 

Spherical Shape: Only about 1/3 of the Abell PNe appear to be truly circular.  Of these circular objects, some appear to be spherical PNe.  These are believed to be the only PNe originating from a single progenitor central star.  These often appear as a soap bubble, with a translucent interior and a faint rim.  Overall, about 10% of PNe are believed to be spherical, and the percentage here is about the same.  Examples on the poster include 6, 8, 30, 33, 34, 39, and 61.

Bi-Polar Shape:  Overall, about 20% of PNe are believed to be bipolar.  These PNe have the most interesting shapes.  To create such an axisymmetric and complex system, it is believed that the progenitor is likely a binary star system.  One of the stars, late in its life during its AGB phase, grows so large that its outer envelope forms a swirling equatorial disk (torus) around the companion.  The disk constrains the companion’s bi-polar flow, forming two polar lobes which expand (and sometimes break through) over time.   

Bi-polar PNe viewed side-on appear like an hourglass or "figure-8", like the prototype object M76.  These objects have a bright central torus section with the brightest portion being the red HII signal on the left and right edges. The bi-polar lobes extend upwards and downwards.  In this poster, the only classic side-on bi-polar object is 22.  In 22, the faint bi-polar sections at top and bottom are seen to create the hour-glass shape.  

Many times the bi-polar lobes at top and bottom have not expanded, resulting in fainter rims top and bottom but still maintaining an overall oval shape to the nebula.    This is seen in 44, 49, and 80.

Much later in the development of a bi-polar PN, the top and bottom bi-polar sections have already broken out and are no longer visible.  This is seen in 14, 19, 55, 82 and 84.

Finally, a bi-polar PN viewed end-on appears as a bright thick torus.  Examples include 20, 53, and 81. 

Elliptical Shape:  The majority of PNe are believed to be elliptical. In this case, like the bipolar case above, the progenitor is believed to be a binary star system. For this case, however, the companion star orbits closer to the progenitor star so that it lies within its envelope for at least a portion of the formation time.  The resulting nebula then takes on more of an elliptical shape. These are seen as oval shapes (sometimes rings) with uniform brightness around the circumference, as seen in 9, 13, 18, 26, 27, 40, 47, 48, 52, 58, 59, 63, 69, 72, and 75.  Our views of these rings are typically at a slight angle, resulting in the oval shape (instead of a circular ring).

Multi-polar Shape:  Multi-polar nebulae have lobes along more than 1 primary axis.  This is likely because the polar axis direction is changing over time.    I believe we are seeing multi-polar nebulae in 24, 38, 47, 78, and 79.

Hexagon Shape:  Hexagon outer PNe rims are seen in many PNe: 1, 2, 3, 10, 18, 23, 26, 27, 37, 56, 58, 70, 71, 83 and 84.  Such hexagon shapes are rampant in nature and appear in galaxies and on planets as well.

Owl-type Shape:  Owl-type PNe have M97 as the prototype.  These PNe have the following characteristics:

- Dominant OIII signal
- Spherical shape (circular in projection)
- Occluded disk
- Dim central star
- No strong rim
- Appearance of dark oval void regions.  

These objects include 2, 4, 23, 33 and 50.

Progenitor Stars:  The presence (and absence) of progenitor stars in these PNe are fascinating to me.  The prototype faint cyan central progenitor stars are seen in 16, 20, 25, 30, 31, 34, 39, 46, 51, 52, 58, 60, 61, 62, 66, 71, 74 and 75.

Some progenitor stars seem unusually bright – perhaps they are not progenitor stars at all but are simply nearby stars superpositioned over the exact center of the nebula.  These brighter central stars include 14, 15, 19, 43, 63, and 78.        

Bright Arcs: Some PNe have unusually bright arc features, appearing as a spider web.  These include 21, 43, 72, 78 and 79.

ISM: The impact of the interstellar medium (ISM) on the PN shape, creating an asymmetric object, is seen in many of the PNe, including 13, 21, 52, 59, 62 and 75.

Enigmata: Some of the PNe are simply difficult to understand and, to me, resemble HII regions more than PNe in appearance.  They contain no OIII signal.  These include 45, 71, and 77.  Based on its distance and size, both outliers for this group, I believe that 77 is a HII region and not a PN.

PNe are beautiful and mysterious objects - I anticipate that our field will discover much more about them in the coming years.

The Revisions section contains location and technical information on each object, including size, distance, and magnitude.  The information is taken from many sources and is subject to some uncertainty.

If you would like to read more about any of these objects, each of the objects in the poster has previously been uploaded and described individually on Astrobin. They all reside in my 
Astrobin Abell PN Collection.