Looking Up: The Wild Duck Cluster
In a small telescope or binoculars this wonderful cluster of stars seems to resemble a flock of wild ducks in flight. However, as we will discuss, the light capturing power of today’s larger telescopes and sensitive cameras capture so many more stars, that it tends to obscure the appearance of the V shaped flock.
This object is known officially as M11. It is an “open cluster” of predominately blue/white stars.
It is found in the constellation of Scutum (the shield) just south of the constellation Aquila (the Eagle). The cluster is just beyond the capability of most humans to see with the naked eye, but shows up nicely in a small telescope.
M11 is interesting for a number of reasons. First, being just beyond the edge of seeing with the naked eye means that when the first telescopes were invented it was an early discovery. So, it was initially discovered by German astronomer Gottfried Kirch at the Berlin Observatory back in 1681. It looked like a fuzzy blob to him.
Next came the English clergyman, William Derham. He resolved the blob into stars with a better telescope. He wrote that “It is not a nebulose, but a cluster of stars.” Derham also recognized the similarity of the brightest stars to each other, probably because of their striking blue color.
Now, on the night of May 30, 1764, the famous French astronomer Charles Messier sees the cluster from his perch on the rooftop of a Parisian hotel. He writes in his log: “Cluster of small stars – which one can only see in a good instrument; with an ordinary telescope of 3 feet it resembles a comet” (i.e its blurry).
To Messier’s credit, while he titles the cluster as M11 in his catalogue, he does recognize that Kirch actually discovered the object back in 1681.
Enter the “Wild Duck” story. With an even better telescope a man named Admiral William Henry Smyth looks at M11 in July 1835. He sees a pattern in the star cluster. It looks like a flock of wild ducks. So he names it the “Wild Duck Cluster.” This nickname has stuck around to this day.
The image shown in this article shows the way it looks in 2018 with an even better telescope combined with a highly sensitive CCD camera, and the extremely dark skies of the Atacama Desert in northern Chile.
So M11 provides us with a seamless story of how things progress over the years in astronomy. First, Kirch in 1681 sees a “blob” through a primitive telescope, then Derham sees that the blob is really made up of stars, then Messier sees more stars, then in 1835 Smyth observes a pattern in the star cluster that he sees as a flock of wild ducks. Finally, our picture above brings out so many additional stars that it is hard to distinguish the V shaped flock anymore. Although if you look carefully at the picture, and try to concentrate on just the brighter stars, you will see the “V” shape towards the bottom.
M11 is very old for an open cluster of stars. The member stars were all born out of the same nebula about 250 million years ago. The cluster numbers about 2900 stars and lies about 6,000 light years away.
The cluster is “metal rich”, and any planets circling the individual stars would be expected to be rich in metallicity also. Like our own solar system with its star, and planets.
Ted is a member of the Everglades Astronomical Society. Organized in 1981 it serves the Naples community, providing information in all aspects of amateur astronomy. Its goals include educating the general public, school children and other groups to the wonders of the universe. The society meets at 7 p.m. every second Tuesday of the month at the Norris Center (public invited). Regular viewing visits to a special, dark sky site in the Everglades are held each month, allowing the general public to observe the night sky through telescopes, under pristine conditions. For more information, visit the website at http://naples.net/clubs/eas. A Blu-ray disc for viewing on TV is now available which features 70 of Ted's deep space images with original background music. For more information, go to www.naples.net/clubs/eas/sales.html.