the sun has gone through some interesting developments.
We have one last phase and it's the pretty one.
So the sun does get to go out with a pretty sight.
What happens? Remember when we stopped we said that the
thermal pulses were going to eject the envelope of the star.
What we would be left with is the inert. Not fusing, no energy source.
Completely degenerate Carbon Oxygen core. This is an object, we'll talk about it,
it's called a whi, it starts out life as what we call a white dwarf.
It's got about the radius of earth. It's got about the mass of the sun.
It's extraordinarily dense. It's extraordinarily hot even though no
fusion is going on because it just stopped being the core of a star that was
fusing Helium and Hydrogen and so on. And was compressed by great masses.
So this object has temperatures in, of many tens of thousands of Kelvin.
It is surrounded. by the atmosphere that it ejected which
since it was ejected has been moving steadily out into space.
what you have therefore is an expanding bubble of gas surrounding an object with
temperatures in the tens of thousands degrees.
the ultraviolet light produced by this exposed core is of course going to ionize
the gas. That's been expelled.
The ionized gas will then glow in the same way the aurora glows and the same
way that lighting glows. And, the resulting objects are some of
the prettiest in the sky, so we're just going to spend a few minutes relaxing,
and. Viewing them because they are pretty.
They're called planetary nebulae because they look round in a small telescope.
They look somewhat like a gas planet would.
This is the ring nebula. We talked about it in our first,
Video clip and promise to come back and explain what this beautiful object is so
what this beautiful object is, is in the middle sits a white world star and these
are the ejector that they form these planetary nebule can be a light year or a
couple of light years across before the material melts into the interstellar
media taking with it some of the carbon and whatever that the star produced
dredged up and ejected in its solar wind so they seed the planetary nebula is the
stars we have seedingly interstellar media with heavier elements
And we see here oxygen and nitrogen lines in the colours, the red is, ionized
hydrogen, these are the H alpha lines, and,
What we, at some point, people thought that this was sort of a slice through a
spherical bubble of gas. It was discovered, upon closer
examination, that in fact, just like the T Tauri Winds, the planetary nebulae, the
atmosphere of a star gets ejected, but not in spherically symmetric way but in a
biploar flow. So this thing has the shape of a
cylinder. The axis of the star's rotation happened
to have pointed at Earth. So we're looking down.
A tube of the cylinder other nebulee we get a different view angle, so we get
more of a picture of the structure. This is the Helux nebula, the cat's eye
is certainly instructed in telling you that there's more structure than just
spherical. There's a lot of interesting questions
here this one is very nice, its not the dumbbell, it's a.
Another one, but it does show very nicely the bipolar nature of the ejecta coming
out of the store. I believe this was a Christmas astronomy
picture of the day. This is one whose intricate structure
apparently follows from several generations of a.
Ejection of material, in between which the axis of the star rotated perhaps
because a binary partner was influencing it or something.
So that we have ejections in several different direction and the combination
makes for this beautiful shape. Conotary nebulus if nothing else, they're
very interesting but also extraordinary pretty and they deserve some aesthetics.
Before we move on with sun.