Messier 27 (HOO)

on

Messier 27 is called the Dumbbell Nebula or the Apple Core Nebula and if you see an image of it you wonder why. For visual observers the name is quite apt. The central blue section looks like an apple core when seen through the eyepiece. However, the camera can integrate a lot more light than our eyes can and shows M27 in its full extent. Even most images only show the footballs shap surrounding the apple core but if you integrate enough light the faint outer shells become visible.

In this case we had planned to gather 20 hours o flight split equally between oxygen III and hydrogen alpha but that left the faint outer shells hard to process so we doubled that and ended up with a bit over 40 hours. That did the trick! the outer bands were a lot easier to process thanks to the extra time reducing the noise.

M27 is a planetary nebula and though it looks like a violent place, compared to a supernova its pretty tame. When a star similar to our sun reaches the end of its ability to keep fusion going in it’s core it stars to lose some of its atmosphere. That “puffs” of the star in shells over time. You can distinctly see a bunch of shells in this image.

This is an HOO image (hydrogen in red and oxygen in blue and green) so it approximates the actual color of the nebula however the dynamic range has been compressed to make both the faint outer fringes and the bright central core visible. In most images you’ll see a bit more contrast at the center but that had to be sacrificed here to allow the outer shells to be seen. Or at least I couldn’t think of a way to both preserve that contrast and show the outskirts.

M27 is about 1,360 light years away in Vulpecula. It’s fairly small at only 8 arc minutes across (a bit more with the outer shells) and fairly bright an apparent magnitude of 7.4. Though not visible in this image, there is a white dwarf at the center of M27 that is providing the light that excites the nebula. The white dwarf is the remains of the star and though it’s no longer fusing in the core it is so hot that it emits a lot of ultraviolet light. The nebula is a transient phenomenon — it’s not quite 10,000 years old and eventually the gas will disperse too far to be affected by the white dwarf. We’re lucky to be at the right place and the right time to see this one.

For all the processing details see astrobin.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s