What Is The M34 Open Cluster in Perseus?
The M34 Open Cluster (also known as Messier 34, M34, or NGC 1039) is an open cluster (object type: Galactic Open Star Cluster) located in the constellation Perseus, in the Orion Arm of the Milky Way Galaxy in the Local Group of galaxies. It’s a collection of stars that are physically associated and gravitationally bound to each other.
M34 is 1,500 light-years away from Earth. It is one of the closest Messier objects to Earth and is home to an estimated 400 stars. This open cluster can be found near the M31 Andromeda Galaxy and M33 Triangulum Galaxy.
Messier 34 was probably first found by Italian astronomer Giovanni Batista Hodierna before 1654, and independently rediscovered by French astronomer Charles Messier on August 25, 1764. He included it in the Messier Catalog of comet-like objects.
M34's age and size
M34 is relatively young, especially compared to many other star clusters. Its estimated age is about 200 million years. This relative youthfulness is reflected in the characteristics of the stars within the cluster, such as their temperature, luminosity, and stage in the stellar lifecycle. Based on the classifications and brightness levels of the most prominent main-sequence stars, it can be determined that this cluster is slightly younger compared to NGC 6633, which is a spacious and brilliantly lit open cluster located in the Ophiuchus constellation.
In terms of physical size, M34 is approximately 15 light-years wide. When observed from Earth, it appears to cover an area of about 35 arcminutes across the sky. For context, the full Moon in the sky spans about 30 arcminutes, so the apparent size of M34 is slightly larger than that of the full Moon, although it is much fainter and less condensed.
Number of stars and stellar density in M34 Open Cluster in Perseus
M34 is estimated to contain around 400 stars. This includes a mix of spectral types, predominantly blue-white main sequence stars of spectral classes A and F, typically more luminous and hotter than the Sun (see below my astrophoto of M34 with annotations).
Open Clusters like M34 are characterized by a lower stellar density compared to globular clusters. The stars are loosely bound by mutual gravitational attraction and are spread out over a region approximately 15 light-years in diameter. Given the number of stars and the volume of space they occupy, the average density of M34 is much lower than that of the core regions of globular clusters or the central areas of galaxies. However, it is still higher than the average density of stars in the vicinity of the Sun within the Milky Way.
What Are The Other Objects Surrounding the M34 Open Cluster?
- Located near M34, the Double Cluster (NGC 869, h Persei, and NGC 884, Chi Persei) is a famous pair of open star clusters that are visually close to each other in the sky. These clusters are a highlight for amateur astronomers due to their beauty and the contrast they provide when observed through a telescope.
- The famous eclipsing binary star system in Perseus, Algol (Beta Persei) also known as the “Demon Star”. It’s known for its regular brightness variations that are noticeable even to the naked eye.
- The California Nebula (NGC 1499) is an emission nebula located near Perseus, named after its resemblance to the shape of California. It is a popular target for astrophotographers.
- The brightest star in the northern constellation of Perseus is Mirfak (Alpha Persei), outshining the constellation’s best-known star, Algol (Beta Persei).
- NGC 1333 is a beautiful reflection nebula in the northern constellation Perseus which has the nickname “The Embryo Nebula“.
- M76, also known as NGC 650, the Little Dumbbell Nebula. It’s a planetary nebula in the northern constellation of Perseus which is also known under the nicknames “The Barbell Nebula“, or “The Cork Nebula“.
Observing and Photographing the M34 Open Cluster
Observing and photographing the M34 Open Cluster in Perseus can be a rewarding experience for both (amateur) astronomers and astrophotographers.
M34 has an apparent magnitude of 5.5 and is best observed from the Northern Hemisphere during the fall and early winter months, October, November and December. The open cluster is high enough in the night sky for viewers in the Northern Hemisphere during this period.
While M34 can be spotted with the naked eye (barely) under dark skies, binoculars or a small telescope will significantly enhance the viewing experience when light pollution is low. Binoculars can reveal the open cluster as a hazy patch, while a telescope will resolve individual stars. In an ordinary telescope of 3 feet (0,9144 meters) in focal length, one can distinguish the stars.
I have observed Messier 34 several times with my 10×50 binoculars and it was always gorgeous to see, just like I was amazed when viewing Messier 13 with the same 10×50 binoculars (see my blog post about M13: https://beatriceheinze.com/portfolio/m13-the-hercules-globular-cluster-2/ ).
M34 is located in the constellation Perseus. You can find it by first locating the constellation Cassiopeia, which has a distinctive “W” shape. M34 can be found slightly southwest of Cassiopeia, which is a constellation and asterism in the northern sky. It is named after Cassiopeia, the proud queen and mother of Andromeda, as depicted in Greek mythology. Messier 34 is easy to spot between the stars Algol and Almach.
To get the best view, choose a location away from city lights where the sky is dark. Although light pollution significantly reduces the visibility of deep-sky objects like M34, it doesn’t mean that Messier M34 can’t be an excellent target on moonlit nights or in light-polluted areas. This open cluster will stand up well to less-than-perfect sky conditions. You can see my astro image of M34 as proof :-). It was imaged from Bortle Class 6 skies (see also “Astrophotography” and “Image details” below). I have photographed several times open clusters and globular clusters during nights when the Moon was up.
A DSLR, a mirrorless camera or a dedicated astronomy camera is suitable for photographing M34. For lenses, a telephoto lens or a telescope with a camera adapter will work best. Use a sturdy tripod for stability. An equatorial mount is ideal as it can track the movement of the sky, allowing for longer exposure times without star trails. For my astrophoto of M34, however, I did not use any guiding system: no guide scope or whatsoever (see “Image details”).
Astrophotography
I took this image with my 8″ Newtonian telescope and a one-shot color camera, the ZWO ASI 294MC Pro, during a 44% Waning Crescent Moon with low and high clouds in between. The seeing was average (Seeing 4/2, info Meteoblue.com).
Normally, I prefer to shoot star clusters without a filter because the colors of the stars look more beautiful and natural. But for this target, I used a multi-purpose filter, the Optolong L-Pro, that is designed to improve the visibility of various deep sky objects and suppress light pollution. It was meant as a test but I’m quite happy with the result. The star colors of the stars in the foreground as well as in the background came out pretty nice. And if you look closely, you can find several little galaxies in the picture.
Image details
- Telescope: Sky-Watcher Explorer Black Diamond N200/1000
- Mount: iOptron CEM60 on iOptron tri-pier
- Camera: ZWO ASI294MC Pro
- Filter: Optolong L-Pro
- Telescope control: ZWO ASIair v1
- Software: Astro Pixel Processor (stacking & pre-processing) & PixInsight (post-processing)
Data captured on the night of 28/10-29/10/2021 => Total integration time: 5.61 hours
SQM-L (average): 19.00 -> Bortle Class 6
No guiding, no coma corrector
Conclusion
In summary, M34 in Perseus is a fascinating and accessible object for both professional astronomers and amateur skywatchers, offering a window into the life and evolution of stars within such a cluster.
Whether you’re observing with your eyes, binoculars, or a telescope, or capturing the cluster with your camera, M34 offers a splendid view of a star cluster that is both beautiful and scientifically interesting.
Perseus’ open cluster M34 will captivate you with its mesmerizing beauty and will leave you with an impression that defies explanation.
