The Ring [planetary] Nebula

Event Date: February 11th

Time: 6:00 AM

Brief

   Although we have looked at Vega several times over the last few months since it started rising before Sunrise, I have spent very little time with a famous deep-sky object close to it: the Ring Nebula (Messier 57).  Commonly referred to as "The Ring" for short, it is a planetary nebula, as opposed to an emission nebula;  The Orion, Lagoon and Omega [nebulae], as examples of the latter.  Before reminding of the differences, also talked about in the provided links, let us first look at the location of The Ring within the stick-figure constellation of Lyra the Harp.  That is followed by a 1/4º field showing the nebula zoomed and showing its namesake shape: Even at the low magnification, notice the different colors, which can only easily be obtained by powerful enough telescopes without long-exposure photography.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   The colors that you see above for the ring are light emitted by helium (blue), oxygen (green) and carbon red).  As provided in the link I provided in the brief, here is the definition of a planetary nebula:

"a star can no longer support itself by fusion reactions in its center. The gravity from the material in the outer part of the star takes its inevitable toll on the structure of the star, and forces the inner parts to condense and heat up. The high temperature central regions drive the outer half of the star away in a brisk stellar wind, lasting a few thousand years".

  In the case of the emission nebula, such as Orion's, the very young stars "emit" ultraviolet radiation is extremely hot, and gives a cloud of color to the area surrounding the stars.  When looking at the link for that one, notice the difference in appearance between each type.

Getting back to planetary ones and specifically The Ring, the shell could have blown off over 20,000 years ago.  Will it continue to expand and increase the size of the nebula?  Not noticeably during our lifetime!

When looking at the second image, we can see that in angular size, the Ring is small, at 1 arc-minute in angular size.  

Worth noting: When magnifying the Ring, do so by adding more a little at a time.  If too much magnification, it may seemingly increase the size, yet degrade the contrast so the color cannot be seen easily.  Try between 150-200 magnification with a telescope that allows such: 4 or higher.  Do you see the ring shape and--using averted vision--any of the colors?  When high enough in the sky, I can see (or think I can see!) a little green with my 8" Cassegrain.  Therefore, hopefully a telescope larger in aparature shows even more color,  Enjoy it, if you can find The Ring easily.