Image from Al Sadeem Observatory on the night of August 16-17, 2018 using the observatory’s Meade LX850 16” SCT and SBIG STT-8300MM CCD camera. Total exposure time is 1 hr 30 min (30 mins per filter). Image stacking and processing were done in Pixinsight and Photoshop.
ABOUT THE NEBULA
The Ring Nebula (also known as Messier 57 or NGC 6720) is a prominent planetary nebula located about 2000 light-years away from Earth in the constellation of Lyra (the lyre).
The discovery was credited to the French astronomer Antoine Darquier de Pellepoix in February 1779, though his colleague Charles Messier first spotted it a month earlier in January 1779 while observing the Bode’s comet.
When a low-mass stars like our Sun (particularly stars with stellar mass of less than 8x solar mass) reaches the end of its red giant stage when nuclear fusion ceases, it will expel its outer layers creating a shell of ionized gases being illuminated with a remnant white dwarf about the size of Earth at the center, thus creating a planetary nebula. This will be somewhat the Sun’s ultimate fate after 5-6 billion years.
The colorful oval-shaped structure of interstellar gas contains different layered elements such as doubly-ionized oxygen, molecular nitrogen, molecular sulphur, and helium. The dim white dwarf star at the center (app. magnitude of 15.75) has a surface temperature of about 125,000K. The central dwarf star expelled its outer layers about 6000-8000 years ago with a current radius of 1.3 light-years expanding at an approximate rate of 19km/s.
With an apparent magnitude of 8.8 and it is relatively small, the nebula cannot be resolved using small binoculars or telescopes. Instead, 8-inch or larger aperture telescopes is needed to see the well-defined ring shape nebulosity and interior hole.
The Ring Nebula is best seen during the summer months (June, July, August) when it is higher in the sky, together with the familiar asterism the Summer Triangle and other fascinating deep-sky objects found in the region. The nebula is situated few degrees to the south of the brilliant star Vega. More particularly, it is found in the region between two other bright stars Sulafat and Sheliak.
Mathewson, S. (2017, April 26). Who 1st Saw the Ring Nebula? 238-Year-Old Mystery Is Solved. Retrieved from https://www.space.com/36616-ring-nebula-study-credits-messier-discovery.html
Messier 57: Ring Nebula (2015, June 11). Messier Objects: Guide to the Bright Galaxies, Nebulae and Clusters Listed in the Messier Catalogue. Retrieved from http://www.messier-objects.com/messier-57-ring-nebula/
Plotner, T. (2017, September 25). Messier 57 – The Ring Nebula. Universe Today. Retrieved from https://www.universetoday.com/36306/messier-57/
Ring Nebula (M57) in Lyra (2013, May 26). Constellation Guide. Constellations: A Guide to the Night Sky. Retrieved from http://www.constellation-guide.com/ring-nebula-m57-in-lyra/