For those of us old enough to remember riding on an old fashioned carousel, there was once a quaint custom where the operator would hold a brass ring out and the lucky contestant who captured it could ride again for free. Before you dismiss this astrophotograph as just another colorful look at a Messier, perhaps you better step inside the workings of the merry-go-round to learn more about what you’re really seeing here… Because this ring is pure gold.
Discovered by Antoine Darquier de Pellepoix in January of 1779 and independently discovered and cataloged by Charles Messier just a few days later, the famous comet hunter himself described it as being “a dull nebula, but perfectly outlined; as large as Jupiter and looks like a fading planet.” Perhaps it was that very description which coaxed Uranus’ discoverer – Sir William Herschel – to have a look for himself and class such objects as “planetary nebula“. Fortunately, Herschel’s telescope resolved M57 to a far greater degree and his descriptions were “a perforated ring of stars… none seems to belong to it.” Since that time, astronomers have been turning an eye towards this “curiosity of the heavens” in a great effort to not only understand its cause – but to capture it as well.
In 1800, German astronomer Friedrich von Hahn was the first to resolve out the Ring’s central star – a planet-sized white dwarf variable star which has an average magnitude of 15. At one point in its Mira-like life, it began shedding its outer layers in what we now believe to be a cylindrical shape and what we see is the bright torus of light from our point of view. Of course, none of this is particularly new news about the 2,300 light year distant M57. Nor is the knowledge when we are looking down this tunnel of expelled gas that we are seeing a decreasing ionization level as the distance from the central star increases. For all who have seen the Ring with their own eyes the innermost region appears dark – the result of only ultra-violet radiation. What we can capture visually is the inner ring, glowing brightly with the greenish forbidden light of doubly ionized oxygen and nitrogen. Where the true prize lay is much like a carousel – it’s just outside where only the red light of hydrogen can be excited.
In 1935 an astronomer named J.C. Duncan discovered something a bit more about the Ring than we knew – an extended halo of material which is all the remains of the star’s earlier stellar winds. It took the power of the Hubble telescope to resolve out dust filaments and globules, but now I invite you to take a closer look at which took 40,000 years in the making and spans 500 times the size of our own solar system.
It took Dr. Dietmar Hager a full month of work to compile some 12 hours of exposure time to reveal what you see here, but the results from StarGazer Observatory are nothing less than amazing. Like the Hubble Telescope images of M57, this image reveals small clouds of dark dust which have flowed out from the central star and are captured in silhouette against the glowing walls of the planetary shell. According to what we know, “These small, dense dust clouds are too small to be seen with ground-based telescopes, but are easily revealed by Hubble.” What’s more, the outer filaments only recently came to public light as ” The Spitzer Space Telescope’s powerful infrared vision detected this material expelled from the withering star.”
Congratulations, Dr. Hager. You have managed with a 9″ Earth-based refractor to capture for us what took two space telescopes to first reveal – along with a distant background galaxy in the full sized image. At least in my book, that means you’ve done far more than just reach for the brass ring…
You’ve captured pure gold.
Tammy was a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She’s received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter’s Gold Status.
(Tammy passed away in early 2015… she will be missed)