Messier 39 – Wide Field in Cygnus
Key Scientific Data
Object type: Open star cluster
Constellation: Cygnus
Other designations: M39, NGC 7092
Distance from Earth: approximately 800–850 light-years
Physical diameter: approximately 7–10 light-years
Apparent size: approximately 30–32 arcminutes
Apparent magnitude: approximately 4.6
Estimated age: approximately 250–300 million years
Estimated members: a few dozen confirmed and probable stars
Right Ascension: 21h 31m 48s
Declination: +48° 26′
Catalogued by: Charles Messier, 1764
Location: Milky Way – Galactic disc
Light-travel time: approximately 800–850 years
Description
This wide-field image of Cygnus reveals Messier 39, a nearby open star cluster located approximately 800–850 light-years from Earth, surrounded by one of the richest stellar regions of the Milky Way.
M39 consists of a few dozen loosely distributed stars, forming a broad cluster approximately the apparent size of the Full Moon.
At this wider scale, however, the cluster becomes part of a much larger Galactic landscape, filled with countless stars, dark interstellar clouds and faint nebulosity.
The image therefore provides not only a view of M39 but also a remarkable perspective on the complex structure of the Milky Way's disc.
M39 – A Young Stellar Family
The stars of M39 formed together from the same molecular cloud approximately 250–300 million years ago, sharing a common age, distance and chemical composition.
Unlike dense globular clusters, M39 has a relatively loose structure and contains only a few dozen principal members.
Several of its brightest stars display a distinctive blue-white colour, indicating surface temperatures higher than that of the Sun.
Over time, gravitational interactions with surrounding stars, molecular clouds and the Galaxy itself will gradually disperse the cluster, returning its members to the general stellar population of the Milky Way.
The Dark Nebulae of Cygnus
One of the most striking features of this wide-field image is the presence of numerous dark interstellar cloudssilhouetted against the dense stellar background.
These structures contain cold gas and dust that absorb and scatter visible light from more distant stars, producing dark lanes and irregular patches across the field.
Far from being empty regions, some of these clouds contain the material from which future generations of stars may form.
Their appearance reveals the complex distribution of matter within the Galactic disc, where stars, molecular clouds and diffuse interstellar dust coexist across enormous distances.
A Window into the Milky Way
Cygnus lies along one of the richest portions of the Galactic plane, providing a particularly dense view of the Milky Way's stellar population.
The countless stars visible in this photograph occupy very different distances. Some lie closer than M39, while others are located thousands of light-years farther away.
Their varied colours reflect differences in surface temperature, from hot blue-white stars to cooler yellow, orange and red stars.
The wider field also contains faint nebulosity associated with interstellar gas and dust, revealing an environment far more complex than an isolated star cluster.
This makes the photograph a small cross-section of the Milky Way, combining stellar populations and interstellar structures within a single composition.
Curiosities
M39 is bright enough to be visible to the naked eye under sufficiently dark skies, appearing as a faint, misty patch in northern Cygnus.
Its large apparent diameter makes it particularly suitable for binocular observations and low-magnification telescopes. At higher magnification, the cluster's widely separated stars may extend beyond the field of view.
Charles Messier catalogued M39 in 1764, describing it as a cluster of stars without nebulosity.
The William Optics RedCat 51 provides a much wider perspective than the Artesky ARTEC 250 Pro, revealing the surrounding Galactic environment rather than concentrating on individual cluster members.
Looking Back in Time
The light captured from M39 began its journey approximately 800–850 years ago, during the 12th–13th centuries, when Europe was still in the Middle Ages.
At that time, the Renaissance had not yet begun, and the invention of the astronomical telescope was still several centuries away.
However, the other stars and interstellar structures visible across this wide field lie at different distances, meaning that their light has travelled for different lengths of time.
Some nearby stars are seen as they appeared only decades or centuries ago, while more distant stellar populations are observed thousands of years in the past.
The photograph therefore combines different distances and epochs within a single field of view, offering a perspective on both the structure and history of our Galaxy.
Image Data
Total integration time: 8h 09m
Integration by filter:
- L-Pro: 8h 09m (163 × 180")
Equipment:
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Telescope: William Optics RedCat 51 III WIFD
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Camera: ToupTek ATR2600M
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Mount: 10Micron GM2000 HPS II
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Filters: Optolong L-QEF 2", Optolong L-Ultimate 2"
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Accessories: ToupTek AAF Electric Focuser, WandererAstro WandererBox Pro V3, ZWO EFW 7×2"
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Software: Adobe Photoshop, Pleiades Astrophoto PixInsight, Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA)
For further details and the full-resolution image, visit AstroBin: