What is Planetary Nebula?

[Littlemews]

On today's Astronomy Test, I pick "B" for that question.

B) Planetary Nebula is some kinda Molecular Cloud.

So in that case am I'm right? or Wrong?

[Fraser]

It really depends on the other possible answers.

A planetary nebula is the cloud of material hurled out when a star becomes a supernova.

But, I suppose the material is made up of molecules, so that could be correct.

[Dave Mitsky]

Originally posted by fraser@Nov 26 2003, 08:30 PM
It really depends on the other possible answers.

A planetary nebula is the cloud of material hurled out when a star becomes a supernova.

But, I suppose the material is made up of molecules, so that could be correct.

Actually a planetary nebula is the expanding shell of gases from a star with a mass similar to that of the Sun. It is the final result of periodic expansions and contractions that occur when elements of increasing atomic number undergo fusion. The nuclear core of the star, which is known as a white dwarf and is often referred to as the central star, remains and can be seen in many cases through amateur instruments, the Blinking Nebula (NGC 6826) in Cygnus for example.

A supernova occurs when a star at least 8 times more massive than the Sun undergoes extremely rapid collapse when the fusion process hits a dead end at iron (no net energy production) and there is insufficient radiation pressure to counteract gravity (a type II supernova) or when one star in a close binary system has siphoned off enough mass from its companion to trigger a massive thermonuclear explosion (a type Ia supernova). All novae are the result of such explosions on one star in a binary system on a much smaller scale.

A molecular cloud is a collection of chemical molecules in the interstellar medium mutually attracted by gravity. It is a nebula that has the potential for star formation.

Sorry about the first incomplete post. I wasn't able to edit and revise it since I hadn't logged in beforehand.

Dave Mitsky