Monday, October 25, 2021

The Gum nebula

Among the various celestial objects visible from Earth, the Gum Nebula plays a very particular role.

Located about 1500 light years from Earth, the nebula can be described as an immense sphere of gas with a diameter of a thousand light years!

Observed from our planet, the nebula has an apparent diameter greater than 30 degrees: for comparison the apparent diameter of the full Moon is only half a degree!

A question, however, arises spontaneously at this point: why if we raise our eyes to the sky we do not see this nebula?

The answer is very simple: being so large, the nebula is extremely diffuse, so much so that it is practically impossible to observe it in the wavelengths of visible light.

Exceptions are some regions denser than the average, such as the structure shown in the figure, a Herbig-Haro object in which new stars are being born.

The Gum Nebula was interpreted to be the remnant of an ancient supernova explosion. For this reason it is being intensively studied by astronomers, who try to understand the interactions between the expanding gas bubble and the surrounding molecular clouds. According to astronomers, these interactions between gas could in fact be at the basis of some star formation phenomena.

Credit: ESA, Hubble, NASA, B. Nisini.


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