M11 - Wild Duck Cluster
| Polish version is here |
Open clusters are loose grouping of stars that formed from the same molecular cloud. They usually contain a few dozen to several thousand members, are relatively young — generally no older than a few hundred million years — and are concentrated primarily within the Galactic disk. The Wild Duck Cluster is a textbook example. It sits in the constellation Scutum, a region of sky beside the Milky Way that is rich in stars and nebulae. The constellation was originally named Scutum Sobiescianum (Sobieski’s Shield) by Johannes Hevelius to honor the Polish king Jan III Sobieski for his 1683 victory over Ottoman forces led by Grand Vizier Kara Mustafa at the Battle of Vienna.
The cluster was first noted in 1681 by Gottfried Kirch, who saw only a diffuse patch of light. William Derham resolved it into individual stars in 1733, and on May 30, 1764 Charles Messier placed it in his catalog as object 11. Today the age of the cluster is estimated at about 250 million years — typical for a compact open cluster still bound by its own gravity.
Observations
June 21, 2025, about 11:00 p.m., Jaworzno, Poland
urban conditions, high level of light pollution
Begin your search by finding the constellation Aquila and its brightest star, Altair α Aquilae. Altair, together with Deneb α Cygni in Cygnus and Vega α Lyrae in Lyra, forms the well-known Summer Triangle. From Altair extend an imaginary line downward to the southeast through Mizan δ Aquilae (also called Deneb el Okab or Djenubi Menkib al Nesr) and Al Thalimain λ Aquilae. The Wild Duck Cluster lies just southwest of Al Thalimain, on the border between Aquila and Scutum. At mid-northern latitudes it appears low above the southern horizon during summer.
The cluster’s integrated visual magnitude is 6.3, so it is invisible to the unaided eye but easy to spot with 10 × 50 binoculars as a small fuzzy patch. Even a modest telescope resolves the dense stellar swarm (Photo 1).
At a distance of roughly 6,000 light-years (1,840 pc), the cluster spans nearly 20 light-years in diameter. Within that volume astronomers count almost 3,000 stars — a remarkably rich population for an open cluster of this size.
Compact, populous, and relatively young, the Wild Duck Cluster captivates both amateur and professional observers. Although it requires at least binoculars or a small telescope, it rewards anyone exploring the summer sky with a memorable view.
Its stars are traveling through space at several dozen kilometers per second. Over the next few million years the cluster will slowly disperse, returning heavy elements such as gold, calcium, and iron to the interstellar medium.
Photo 1 Parameters:
- Total exposure time: 10 minutes (stack of 10 RAW frames at 60s each, using an appropriate number of dark, bias, and flat frames)
- ISO: 1600
- Maksutov-Cassegrain telescope (100/1400), prime focus exposure
- A filter was used to reduce the effects of artificial light pollution and atmospheric glow
- Mount: equatorial mount with tracking, aligned using the drift method and controlled by a custom-built system.
Further readings:
- Wu Zhen-Yu, Zhou Xu, Ma Jun, Du Cui-Hua, The orbits of open clusters in the Galaxy, Monthly Notices of the Royal Astronomical Society, 399 (4), 2009, pp. 2146-2164
- Cantat-Gaudin T., Vallenari A., Zaggia S., Bragaglia A., Sordo R., Drew J. E., Eisloeffel J., Farnhill H. J., Gonzalez-Solares E., Greimel R., Irwin M. J., Kupcu-Yoldas A., Jordi C., Blomme R., Sampedro L., Costado M. T., Alfaro E., Smiljanic R., Magrini L., Donati P., Friel E. D., Jacobson H., Abbas U., Hatzidimitriou D., Spagna A., Vecchiato A., Balaguer-Nunez L., Lardo C., Tosi M., Pancino E., Klutsch A., Tautvaisiene G., Drazdauskas A., Puzeras E., Jimenez-Esteban F., Maiorca E., Geisler D., San I., Villanova S., Gilmore G., Randich S., Bensby T., Flaccomio E., Lanzafame A., Recio-Blanco A., Damiani F., Hourihane A., Jofre P., de Laverny P., Masseron T., Morbidelli L., Prisinzano L., Sacco G. G., Sbordone L., Worley C. C., The Gaia-ESO Survey: Stellar content and elemental abundances in the massive cluster NGC 6705, Astronomy & Astrophysics, 569, 2014, A17
- Casamiquela L., Carrera R., Balaguer-Núñez L., Jordi C., Chiappini C., Anders F., Antoja T., Miret-Roig N., Romero-Gómez M., Blanco-Cuaresma S., Pancino E., Aguado D. S., del Pino A., Díaz-Pérez L., Gallart C., NGC 6705 – a young α-enhanced open cluster from OCCASO data, Astronomy & Astrophysics, 610, 2018, A66
Marek Ples