Bicolor image from Ha and [OIII] - some SII data was mixed into Ha. Star colors are insertet from RGB data.
Object descriptionThe nebula is also referred to as Abell 21 (PN A66 21), after the American astronomer George O. Abell, who discovered this object in 1955.It is also known as Sharpless 2-274 and is located in the constellation of Gemini close to the Canis Minor border. Earlier considered to be a supernova remnant, in the 1970s, researchers were able to measure the movement and other properties of the material in the cloud and clearly identify it as a planetary nebula.
The Medusa Nebula spans approximately four light-years and lies at a distance of about 1500 light-years. Despite its apparent size of 10 arcminutes in the sky, it is extremely dim and hard to observe.
The planetary nebula phase represents a final stage in the evolution of low mass stars like our sun, as they transform from red giants to hot white dwarf stars and in the process shrug off their outer layers. Ultraviolet radiation from the very hot, deep blue star at the core near the center of the nebula's bright crescent shape causes atoms in the outward-moving gas to lose their electrons, leaving behind ionised gas shaped into braided filaments. The turquoise colours derive from doubly ionised oxygen [O III] and red colour from Hydrogen-alpha.
Beyond the braided crescent, additional faint hydrogen-alpha nebulosity, shed earlier by the star, can be seen at the center right and upper right part of the image.
Compiled from different sources:https://en.wikipedia.org/wiki/Medusa_Nebulahttp://www.eso.org/public/news/eso1520/https://apod.nasa.gov/apod/ap121025.html
Comments