CaVa 1 Planetary Nebula

Explanation From Sakib Rasool

CaVa 1 is an obscure ancient planetary nebula that was discovered by the French amateur astronomers Jean-Paul Cales and Michael Vanhuysse in April 2017 and was spectroscopically confirmed to be a true planetary nebula in October 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 analyzing 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 first proposed in 1969 by the Armenian astronomer Grigor Gurzadyan.

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

Taken at Stellar Winds Observatory, a/k/a Stan Watson Observatory in Animas, NM.

Exposure: L,R,G,B,HA,03 225,225,225,225,990,990