Labors of the Hercules Cluster

By Phil Plait | March 7, 2012 7:00 am

We live in the Milky Way galaxy, a collection of more than a hundred billion stars forming a flat, spiral disk. Our galaxy is in turn part of a small group called the Local Group, just a few dozen members strong, of which we are among the largest. But galaxies live in larger groups yet, called clusters. Some have hundreds of galaxies, and some thousands. In the direction of the constellation of Hercules is one such smaller cluster, called (duh) the Hercules Cluster, just under 500 million light years from Earth. The VLT Survey Telescope took a look at the cluster and produced this spectacular picture of it:

[Click to galactinate, and you want to; I reduced the size considerably to fit it here.]

The cluster is unusually rich in spiral galaxies, and unlike bigger groups doesn’t have one, massive galaxy sitting at its core (the result of a bigger galaxy falling to the center and eating lots of other galaxies, growing huge in the process). Still, the small size of the cluster means a lot of its members are interacting, and if you look closely you see lots of them tugging at the others:

That edge-on spiral in the lower right is clearly warped, so I expect it’s suffered a near miss from another galaxy in the past few million years (maybe that little spiral above it, or more likely the severely messed-up fuzzball to the left), and other examples aren’t hard to find.

As an aside, when I was poking around the big image I saw lots of red dots aligned next to green ones on the left near the bottom, and realized that must be an asteroid, captured as it moved slowly across the field of view in the multiple exposures and different filters used to make this picture. A long green streak below that may be another asteroid moving much rapidly, or possibly a satellite that streaked across one exposure.

Take a look for yourself. What do you see?

And a thought for you: This small cluster is part of a larger complex called the Hercules supercluster, made up of many smaller groups like the Hercules cluster. Altogether, the supercluster is something like 300 million light years across… and is still not the largest structure. Hercules, together with the Coma Cluster and Leo Cluster, comprise what’s called the Great Wall: a vast structure that is among the largest in the Universe — it’s so big that even at its distance of several hundred million light years away it spreads across more than one-third of the visible sky!

Thinking about these types of things can numb the mind… but remember, the most amazing thing to me about all of this is that we can know them at all. We’re a part of all this, and when we look out at it, when we examine it, we are learning about ourselves. I think peering out into the cosmos so that we can better understand ourselves is one of the noblest things we humans can do, and using science as our tool the best way to do it.

And look what’s it’s given us! The entire Universe! We cannot possibly ask for anything more.

Credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute


Related Posts:

- Slip into the Coma
- The face of beauty
- Galaxy on the edge of space
- Cluster tucked at the far reaches of the Universe

Comments (21)

  1. We live in the Milky Way galaxy, a collection of more than a hundred billion stars forming a flat, spiral disk.

    Maybe we ought to update descriptions of galaxies to mention the halo of dark matter? As I understand it, the dark matter is really responsible for a great deal of the galaxy’s shape and size as well.

  2. Messier Tidy Upper

    unlike bigger groups doesn’t have one, massive galaxy sitting at its core (the result of a bigger galaxy falling to the center and eating lots of other galaxies, growing huge in the process).

    Clearly forming such a supermassive cannibalistic Core Elliptical Giant is too much of a herculean task for such a small cluster – or are the Hercules cluster galaxies just too strong to be eaten so easily? ;-)

    NB. How does this Hercules galaxy cluster compare size~wise with our own local group of galaxies?

    And look what’s it’s given us! The entire Universe! We cannot possibly ask for anything more.

    We-ell, there *is*+ the multiverse with all the extra parallel universes thrown in that we could ask for! ;-)

    (Sorry; couldn’t resist the temptation to jokingly nitpick there.)

    Superluminous image – thanks. 8)

    *****

    + Actual multiverse existence may or may not apply depending on your exact cosmological model!

  3. Chris

    I see aliens. Just seeing all those galaxies you can’t help but wonder how many civilizations are in that “small” picture. How many are looking up towards the sky and wondering if anyone else is out there. Maybe even looking up with their telescopes right back at us. Unfortunately since they are 100 million light years away, all they’d be seeing now is the dinosaurs. And unfortunately there is no possible way for us to ever hope to learn about them.

    On a more astronomical (less philosophical) note, those three galaxies near the center. The elliptical one on the right has two blue blobs above it. Is that some bipolar outflow or some trick in perspective?

  4. Messier Tidy Upper

    @ ^ Chris : Could those be companion galaxies or foreground stars perhaps?

    As for no possible way for aliens from the Hercules galaxies to contact or visit us – there is the idea of wormholes. I’m not saying saying its likely or even remotely plausible but there is a very, exceptionally remote – 0.000001% chance of a wormhole linking one of their galaxies with us – isn’t there?

  5. Peter Davey

    With reference to “Hercules”, Carl Sagan, in “Cosmos”, pointed out that it was the Greeks who first invented the idea of scientific enquiry, and then abandoned it, dooming the human race to many more unnecessary centuries of ignorance and superstition.

    Those who learn nothing from history (or science) …….

  6. CJSF

    @Chris – I wondered the same thing about those blue blobs. I Tweeted Phil about it, but his twitter stream probably flows like Niagara Falls and he missed it.

    CJSF

  7. Sam H

    Hey Phil – the post is a beaut, but I’m interested in something else right now:

    If you don’t know about “Kony 2012″, go watch the YouTube vid when you can, and please make a post of your thoughts on it. It’s not space-related, but this deserves to be on everyone’s mind. :)

  8. James D

    I just blew it up as my desktop background and noticed a greenish blob just starting to show up right in the center, at the bottom edge. Any ideas what that is? Lots of things to see in that photo though. almost makes up for bad seeing last night.

  9. Nick M

    How do you distinguish between a potential asteroid or satellite object in a photo like this and some kind of artifact?

  10. I just can’t find the red & green dots you speak of, Phil! I do see 2 red & 1 blue dot down there…
    Better still, just right of center I see 4 green dots in a tight linear group that are possibly associated. Prolly an OIII filter in play there!

  11. Robert Gibson

    Phil – Is there an accepted number of stars in the Milky Way? I hear everything from 100 billion to 200 billion, and Wikipedia even claims 300 +/- 100 billion!

  12. Brian

    Maybe we ought to update descriptions of galaxies to mention the halo of dark matter?

    I imagine that’ll have to wait until such time as we can actually distinguish enough detail to actually see the halo’s true shape. Right now we can only theorize on anything smaller than the galactic-cluster level.

  13. Astrophysicist Kevin Sorbo has advocated the use of slipstream technology to get around the difficulty of crossing between galaxies.

  14. Jon Hanford

    @ #3 Chris:

    “On a more astronomical (less philosophical) note, those three galaxies near the center. The elliptical one on the right has two blue blobs above it. Is that some bipolar outflow or some trick in perspective?”

    I think the object you’re describing is the peculiar galaxy IC 1182: http://www.eso.org/public/news/eso9834/

    The galaxy seems to have recently undergone a merger with another member of the cluster and the two “blue blobs” represent two newly minted tidal dwarf galaxies located in one of the tidal arms of the post-merger system. A 2004 study of IC 1182 can be found here: http://arxiv.org/pdf/astro-ph/0402219v1.pdf

    IC 1182 is probably my favorite interacting system in Abell 2151, although several interesting Arp objects can be found here too.

  15. Russell

    “I think peering out into the cosmos so that we can better understand ourselves is one of the noblest things we humans can do, and using science as our tool the best way to do it. ”

    I do feel kinda cool standing behind my daughters little 4.5″ telescope….Now I know why!

  16. Mike G

    Phil – Do you know the dimensions of this picture (X degrees/minutes by Y degrees/minutes)? You mentioned the Great Wall stretches across a third of the visible sky. This is obviously considerably smaller than that. Am curious how much smaller.

  17. Jon Hanford

    @16 Mike G:

    “Phil – Do you know the dimensions of this picture?”

    Mike, the ESO website mentions this image covers “a full square degree”, which is also considerably cropped from the full field of view of the VLT Survey Telescope.

  18. Sanjay

    In the top of the second image (about 1 o’clock to the interacting spirals), is that a barred spiral galaxy?

  19. Mike G

    Jon – Thanks for clarification. Cool to be able to point to a section of the section that has the dimensions of two Moon diameters on each side and know that all those galaxies are there.

  20. ozprof

    I contacted ESO for the dates and times of the individual images, and from the information they sent I was able to identify 2 asteroids. They are visible as 2 red and blue steaks in the lower left of the image, one just above the other, and then as 2 green streaks, one closer to the centre of the image and one to the upper right.

    The brighter asteroid is 13006 Schwaar mag 17.7. The other is 2011 KK12 mag 20.2.

    The longer streak at the bottom left does not correspond to any asteroids. It could be a satellite or an NEO. Will need more information from ESO to try and identify it.

  21. Brian Too

    So many worlds caught in a drop of water.

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