The Virgo Cluster
Spring is the season of wonderful galaxies in the life of astrophotographers living on the northern hemisphere of earth. In contrast to summer if we look up to the night sky in the early night-hours one can look away from our own galactic plane out into the endless deep space. The stars of the Milky Way form a beautiful constellation in the souther region of the sky called "Virgo" which is located on its highest elevation during this time. Just northern to Virgo can be found our biggest neighbouring
group of galaxies which dominates our much larger local corner in the universe: the Virgo Supercluster. Because the Virgo Cluster can be well observed with a relatively simple astrophotographic setup I decided to take same captures and collect some informations about it.
Constellations Virgo, Coma Berenices and Leo viewed from the backyard of our house. The Virgo Cluster located between the constellations. Green square: Photo with 100mm lens, Red square: Photo with 800 mm telescope. Terrestial objects and the suburban light pollution hindering deep-sky photography.
Our home supercluster
To better understand this image project please watch this video from Nature publishing group. It shows on a very impressive way the structure of our nearby universe: galaxy clusters and superclusters. Watching the video you can better imagine the scale and position of the images presented below.
The illustration on the right represents the architecture of the known universe. Our Galaxy is a member of the Local Group of Galaxies. This Local Cluster together with many other similar galaxy groups is a member of a much large structure called the Virgo Supercluster. This supercluster was named after its biggest member: the Virgo Cluster (green circle).
Recent publications revealed that the Virgo Supercluster is only a small portion of a even much larger formation called "Laniakea".
The Virgo Cluster of Galaxies
The Virgo Cluster is a group of galaxies whose center is 53.8 ± 0.3 Million light-years away in the constellation Virgo. Comprising approximately 1300 (and possibly up to 2000) member galaxies, the cluster forms the heart of the larger Virgo Supercluster, of which the Local Group is an outlying member.
The Structure of Virgo Cluster
The cluster is an aggregrate of at least three separate subclumps:
Virgo A, centered on M87
Virgo B, centered on M49
Virgo C, centered on the galaxy M59.
The three subgroups are in the process of merging to form a larger single cluster and are surrounded by other smaller galaxy clouds, mostly composed of spiral galaxies, known as N Cloud, S Cloud, and Virgo E that are in the process of infalling to merge with them, plus other farther isolated galaxies and galaxy groups (like the galaxy cloud Coma I) that are also attracted by the gravity of Virgo to merge with it in the future. This strongly suggests the Virgo cluster is a dynamically young cluster that is still forming.
Other two nearby aggregations known as M Cloud, W Cloud, and W' Cloud seem to be background systems independent of the main cluster.
Lens: Canon EF 100mm f2.8 Macro
Camera: Canon 5D Mk III (default)
Mount: Sky-Watcher StarAdventurer Mini
Aquisition data: 23 min (31x45 sec), f4, ISO1600 + Calibration Images
Processing: Nebulosity 4, LightRoom, PhotoShop
In the Heart of Virgo A subcluster:
The Markarian´s Chain of Galaxies
Markarian's Chain is a stretch of galaxies that forms part of the Virgo Cluster. It is called "chain" because, when viewed from Earth, the galaxies lie along a smoothly curved line. Member galaxies include M84, M86, NGC 4477, NGC 4473, NGC 4461, NGC 4458, NGC 4438 and NGC 4435.
Lens: 8" Altair Astro Imaging Newtonian Telescope, focal length: 800mm, f4
Camera: Canon 700D (modified) + Astronomik CLS Filter + Baader MPCC MkIII Field Flattener
Mount: Sky-Watcher NEQ-6 Pro SynScan GOTO
Autoguiding: Orion StarShoot Camera + Finder Scope + PHD2
Aquisition data: 70 min (14x5 min), ISO800 + Calibration Images
Processing: Nebulosity 4, LightRoom, PhotoShop
The wide-field image which I made with a 100 mm lens about the entire Cluster showed already uncountable number of galaxies. This excited me to point my small telescope (200mm aperture - 800 mm focal length) to a very small portion in the heart of the Cluster. After exposing only 70 minutes I saw again an immeasurable depth: hundreds of galaxies, each of them housing millions and millions of stars...
I labelled some of the bigger objects using their catalog number:
M: Messier Objects
NGC: New General Catalog
IC: Index Catalog
PGC: Principal Galaxy Catalog
Physical properties of some of the bigger objects:
M84: elliptical galaxy, diameter: 110 000 light-years, distance: 60 million light-years away
M86: elliptical galaxy, diameter: 147 000 light-years, distance: 52.3 million light-years away
NGC4435 and NGC4438: The Eyes Galaxies -interacting pair- 52 million light-years away
NGC4388: active spiral galaxy 65 million light-years away
NGC4402: edge-on spiral galaxy, 48 million light-years away
The wide-field photo
The wide-field image has been made with a conventional, professional-level DSLR camera and a standard 100 mm f2.8 macro lens mounted on a special star-tracker mobile mini-mount from Sky-Watcher. After setting up the System in the backyard of our house the entire shooting (31x45 sec + calibration data) was performed wireless from the house. The qDSLR dashboard remote shooting software were used with a mobile WiFi router (the white box on the photo) to take the shots. The mount itself generates also a local WLAN and can be controlled through an iPhone-App. This is a very comfortable way for longer photographic sessions through the night.
The telescope photo
The image of the Markarian´s Chain is a conventional telescopic deep-sky photo. I used my present telescope -8" imaging newtonian- mounted on the heavy-duty EQ6 computerised mount. The imaging camera was my astromodified Canon 700D. For the perfect tracking an Autoguider system was also used. Due to the significant light-pollution near our house the use of an Astronomik CLS filter was necessary.