The beginning of the end for a star

Every now and again I’ll see an image of an astronomical object and think, what the heck?

CRL 618 is definitely one such object!

This Hubble image threw me for a sec: it looks like a planetary nebula, but where’s the central star? What are those long fingers of matter? So I started going through the scientific literature and found some good explanations. And I learned something!

CRL 618 is a star announcing it’s on its way to becoming a planetary nebula.



When stars like the Sun die, they expand hugely and cool off, becoming red giants. They then emit a solar wind that is slow (in astronomical terms at least) and dense. After a few thousand years, as the star loses more and more mass from its outer layers, the deeper, hotter part is exposed. The wind emitted speeds up, slams into the slower wind, compressing it, and ultraviolet from the exposed stellar core lights it up. The result is a beautiful planetary nebula, like the famous Helix Nebula.

That’s all well and good, but ...

Full story at http://blogs.discovermagazine.com/badastronomy/2011/03/29/the-beginning-of-the-end-for-a-star/