Wednesday, September 28, 2005

Dumbbell Nebula Messier 27 from last night



I took a quick set of shots of Messier 27, a planetary nebula, last night from Ryerson, after fixing a piece of equipment on the telescope. This is 128 images of 15 seconds added together to make a 32 minute equivalent exposure.

4 comments:

Mary P. said...

That's gorgeous. What is that gossamer bubble made of? My uneducated guess would be gas - from a central star? How big is it? Is it permanent, or in transition from one thing to another? I'm fascinated.

Dean W. Armstrong said...

Yep--at the center of this nebula was an old red giant star. It had burned through all the hydrogen in its core and moved on to burning helium, and this caused the core to contract and be much hotter, inflating the star to hundreds of times larger than before. The outer atmosphere was tenuously connected to the gravity of the star and it streamed out into space. It exposed the naked core of the star, leaving a white dwarf, visible right in the center of the nebula. This star has a surface temperature of over 100,000K and it emits a very large amount of ultraviolet light, which ionizes the expelled gas. When the ionized gas (aka plasma) recombines with the lost electrons, the atoms release light (fluorescing), the light of which you see. This stage in stellar evolution is very quick--some 10,000 years long at most before the gases thin out and all you have is a lonely white dwarf. The outer atmosphere of the star is mostly hydrogen, some helium, and a little of the other elements. Most of the light recorded in the image is from hydrogen and oxygen which emit light in the red and green.

Dean W. Armstrong said...

Oh, also, a good overview of planetary nebula is the entry at Wikipedia -- http://en.wikipedia.org/wiki/Planetary_nebula

Mary P. said...

Thanks for the explanation. Seems I guessed pretty well!

10,000 years is "quick" in cosmological terms. That should put things in perspective: So why is today moving by so slowly?