Will the Sun make a planetary nebula?

[lpetrich]

What will happen when our sun dies? The Sun is expected to become a red giant some 5 billion years from now, and it is expected to end red gianthood by blowing off much of its outer layers. What remains will be a white dwarf that then slowly cools.

Prof Zijlstra explains: "When a star dies it ejects a mass of gas and dust—known as its envelope—into space. The envelope can be as much as half the star's mass. This reveals the star's core, which by this point in the star's life is running out of fuel, eventually turning off and before finally dying.

"It is only then the hot core makes the ejected envelope shine brightly for around 10,000 years—a brief period in astronomy. This is what makes the planetary nebula visible. Some are so bright that they can be seen from extremely large distances measuring tens of millions of light years, where the star itself would have been much too faint to see."

(typo corrected) The problem is that earlier calculations found that the Sun would make a planetary nebula that is much fainter that one from a somewhat more massive star. Prof. Zijlstra's calculations showed that it would be about the same brightness as for 2 or 3 solar masses. This also resolves the conundrum that planetary nebulae in nearby galaxies have the same maximum brightness.

So the Sun will put on a final show that will be as big as what stars a few times its mass will make.

 

[Artemus]

On a side note, I always thought that sun would be fusing helium during the red giant phase. I recently learned (last year or two) that it will actually be fusing hydrogen in the shell around the degenerate helium core in the red giant stage and helium fusion won't start until the horizontal branch stage.

Things that you always knew but actually didn't...

ETA: Seems a lot of people are as confused as I was:

In approximately 5 billion years, the sun will begin the helium-burning process, turning into a red giant star.