"CaVa 1 is an obscure ancient planetary nebula that was discovered by the French amateur astronomers Jean-Paul Cales and Michael Vanhuysse in 2017. It has a size of 8x7 arcminutes and is located in a region of background nebulosity. There is sometimes a relation between the size of a planetary nebula, its age and its relative faintness. Older planetary nebulae over time eventually expand more and the ionizing energy is spread over a larger area as well as the density of the gas being thinner, so therefore exhibit lower surface brightness. This is easily overcome by amateur astronomers who are able to obtain very long exposures. Large low surface brightness planetary nebulae have been discovered in professional Ha surveys and also by amateurs analysing various astronomical survey data.

CaVa 1 consists of primarily Ha emission with some OIII in its interior. The southern part exhibits a tenuous bowshock structure produced by its interaction with the surrounding interstellar medium (ISM). Few examples of planetary nebulae with ISM interaction are known due to their extremely low intrinsic brightness. This stage in the evolution of a planetary nebula precedes the total dilution and fading of a planetary nebula. However, the phenomenon of ISM interaction has been observed in young planetary nebulae with high speed central stars and studies conclude that different stages of interaction are exhibited throughout the life of planetary nebulae. The idea of a planetary nebula interacting with the ISM as it moves through space was proposed in 1969 by the Armenian astronomer Grigor Gurzadyan."

PuWe1 (PNG 158.9 + 17.8), in Lynx, is one of the largest PN, that has an apparent diameter of 20'. It has been discovered by Purgathofer & Weinberger in 1980 on a Palomar sky survey print.
As almost all this kind of old diluted PN, it is very faint and requires long exposures to get details. The Halpha signal is the strongest and draws a ring with several details in the structure while the OIII signal is extremely faint with a disc shape and no visible structure.

PK 164+31.1 Jones-Emberson 1

Explanation APOD: Is this what will become of our Sun? Quite possibly. The bubble of expanding gas pictured above is the planetary nebula PK 164 +31.1, the remnants of the atmosphere of a Sun-like star expelled as its supply of fusion-able core hydrogen became depleted. Visible near the center of the nebula is what remains of the core itself -- a blue-hot white dwarf star. This particularly photogenic planetary nebula shows intricate shells of gas likely expelled at different times toward the end the star's demise, and whose structure is not fully understood. This deep image of PK 164 +31.1 shows many other stars from our own Milky Way Galaxy as well as several galaxies far in the distance. PK 164 +31, also known as Jones-Emberson 1, lies about 1,600 light years away toward the constellation of the Wildcat (Lynx). Due to its faintness (magnitude 17) and low surface brightness, the object is only visible with a good-sized telescope. Although the expanding nebula will fade away over the next few thousand years, the central white dwarf may well survive for billions of years -- to when our universe may be a very different place.

Exposure Details:

Telescope: Planewave 24" f6.7 on a Planewave HD Mount Camera: SBIG 16803

Location: Stellar Winds Observatory at DSNM, Animas, New Mexico

Exposure: L,R,G,B,HA,03 500,210,210,210,1350,1440 65Hours of exposure so far. Still working on the O3 data.

Ferrero 6 (Fe 6, PN G129.6+03.4) Planetary Nebula in Cassiopeia. The bright blue star
above the nebula is BD+64 263 (SAO 12045). This PN was identified by Laurent Ferrero in
November 2013.

The Soap Bubble Nebula PN G75.5+1.7

Explanation From APOD:

Adrift in the rich star fields of the constellation Cygnus, this lovely, symmetric nebula was only recognized a few years ago and does not yet appear in some astronomical catalogs. In fact, amateur astronomer Dave Jurasevich identified it as a nebula on 2008 July 6 in his images of the complex Cygnus region that included the Crescent Nebula (NGC 6888). He subsequently notified the International Astronomical Union. Only eleven days later the same object was independently identified by Mel Helm at Sierra Remote Observatories, imaged by Keith Quattrocchi and Helm, and also submitted to the IAU as a potentially unknown nebula. The nebula s now known as the Soap Bubble Nebula. Most probably it is a planetary nebula, a final phase in the life of a sun-like star.

The Ring Nebula (also catalogued as Messier 57, M57 or NGC 6720) is a planetary nebula in the northern constellation of Lyra. Such objects are formed when a shell of ionized gas is expelled into the surrounding interstellar medium by a red giant star, which was passing through the last stage in its evolution before becoming a white dwarf.