The Bug Nebula

I don't do a lot of 'eye-candy' posts about pictures, but this one really caught my eye as I scanned my Google reader at lunch time today. I've blogged about this before, but this is just an awesome picture from the Hubble Space Telescope.

One of the final stages of stellar evolution of a Sun-like star results in nebulae like this one, NGC 6302, also known as the Bug Nebula. This glowing, expanding shell of ionized gas is known as a planetary nebula.

NGC 6302 The 'Bug Nebula'

Credit: NASA, ESA, and the Hubble SM4 ERO Team

At the end of the star's life, during the red giant phase, the outer layers of the star are expelled via pulsations and strong stellar winds. This is not a nice breeze on a cool day. We're talking winds up to 600,000 miles per hour. Eventually all that is left in the center is the ash of the previous star's core, a white dwarf. The hot white dwarf emits ultraviolet radiation that ionizes the ejected outer layers of the star. This energized shell radiates as a planetary nebula.

They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, as compared to a typical stellar lifetime of several billion years.

So, what does this thing look like through a telescope on the ground? Here is a drawing done by Scott Mellish at the eyepiece of a 56cm Dobsonian telescope, at 314x,  from Australia.