Beautiful Chaos

Article written: 9 Jul , 2009
Updated: 24 Dec , 2015

Can you imagine living in this region of space? Just think of the beautiful views you’d have in the sky – that is, if you survived the chaos as one galaxy is passing through the core of three other galaxies at ridiculous (ludicrous?) speeds (3.2 million km per hour / 2 million miles per hour) generating a shock wave of gas and X-rays.

This is Stephen’s Quintet, A compact group of galaxies, discovered about 130 years ago, located about 280 million light years from Earth. The curved, light blue ridge running down the center of the image shows X-ray data from the Chandra X-ray Observatory. The galaxy in the middle, NGC 7318b is passing through the core of the other galaxies at high speed and is thought to be causing the ridge of X-ray emission by generating a shock wave that heats the gas. The most prominent galaxy in front (NGC 7320) is actually far away from the other galaxies and is not part of the group.

(See the Chandra webpage for a roll-over labeled version)

Additional heating by supernova explosions and stellar winds has also probably taken place in Stephan’s Quintet. A larger halo of X-ray emission – not shown here – detected by ESA’s XMM-Newton could be evidence of shock-heating by previous collisions between galaxies in this group. Some of the X-ray emission is likely also caused by binary systems containing massive stars that are losing material to neutron stars or black holes.

Stephan’s Quintet provides a rare opportunity to observe a galaxy group in the process of evolving from an X-ray faint system dominated by spiral galaxies to a more developed system dominated by elliptical galaxies and bright X-ray emission. Being able to witness the dramatic effect of collisions in causing this evolution is important for increasing our understanding of the origins of the hot, X-ray bright halos of gas in groups of galaxies.

Source: Chandra

15 Responses

  1. Maximan says

    “This is Stephen’s Quintet, A compact group of galaxies, discovered about 130 years ago, located about 280 light years from Earth.”

    That would be a tad too close for comfort I think! Try around 280 million light years from Earth – the view may not be as good but it’s much safer this far out 🙂

  2. Maximan says

    Awesome picture btw…

  3. Jon Hanford says

    Much research has been performed on the region between NGC 7318b and NGC 7319 due to enhanced activity seen in visible, submillimeter, infrared and x-ray wavelengths. Molecular hydrogen and a few extragalactic star clusters have also been detected in this region of Stephan’s Quintet. A recent paper on x-ray and UV observations of Stephan’s Quintet can be found here: . Must be an interesting night sky for any observers in this agglomeration of galaxies!

  4. secondguess says

    Seeing this for the first time is amazing, and the first thought i have is of how devastating it would be if the active cores of any of these galaxies were to get to close.

  5. HeadAroundU says

    I don’t understand how it’s passing through 3 cores. I see 2 galaxies interacting at best. And maybe those two are slightly licking the 3rd one on the upper left.

  6. HeadAroundU says

    The other site says A CORE of 4 other galaxies.

    a or the?

    So, it’s just a point, pointless point :D, between 4 galaxies?

    Core is where supemassive black holes are right?

  7. DrFlimmer says

    @ HeadAroundU

    In this case the “core” is the “geometric” center of all four galaxies combined. At least this is how I understand it. So in this “special” core there is no SMBH since it is not the core of one galaxy, where, indeed, SMBH are located.

    But this is my interpretation and I could be wrong!

  8. Jon Hanford says

    Interesting that no one has mentioned the so-called ‘discordant redshift’ galaxy in this group, NGC 7320 (the bluish galaxy near the bottom of the picture). Halton Arp mentioned that this galaxy’s redshift of z=0.00262 was certainly not in line with the other four (yellowish) galaxies in the picture having an average redshift of about 0.02. Close inspection of the size of HII regions in NGC 7320 do indeed suggest that it is much closer to us than the yellowish linear chain of four galaxies now seen as far in the background. Still, it doesn’t diminish the beauty of this galactic pileup 🙂

  9. Nereid says

    In response to Jon Hanford’s comment: yeah, and no one has mentioned that the *stars* in the image almost certainly all have redshifts MUCH smaller than any galaxy’s redshift … why is it that chance alignment of galaxies gets some people excited while far more numerous chance alignments of stars+galaxies doesn’t?

  10. Member
    IVAN3MAN says


    [W]hy is it that chance alignment of galaxies gets some people excited while far more numerous chance alignments of stars+galaxies doesn’t?

    Probably the same reason why devout religious people get excited over a damn water stain or a stupid piece of toast that happens to resemble (in their eyes only) Jebus (sic) or the Madonna. 🙄

  11. Member
    IVAN3MAN says

    Addendum: By “religious”, I was referring to Christians in general; however, in the case of Muslims, they go nuts over a bloody piece of meat with gristle that happens to spell (in their eyes only) the word “Allah” or “Mohammad”. 🙄

  12. Cosmodog says

    Although I don’t doubt the view of the sky from this part of space would be spetacular, I think viewing it from a distance is even more spetacular. We can see the patterns and colors much better from a distance. And the fact that it took such an advance in technology to image it makes it even more special – like discovering hidden treasure.

  13. Jon Hanford says

    Indeed, Nereid brings up an excellent point that almost all the stellar images in the illustration provided represent stars in our own Milky Way galaxy. Few, if any, stellar images represent distant quasars, galaxies, or extragalactic HII regions in the background grouping (including NGC 7320C, NGC 7319, NGC 7318A-B and NGC 7317). @ Cosmodog, I heartily agree with your post, and can’t wait till we can get a look at this group down to the level of imaging main-sequence stars 🙂

  14. Jon Hanford says

    Btw, NGC 7320 appears to be an outlying member of the nearby NGC 7331 Group (z=0.00272).

  15. wjwbudro says

    Careful IVAN3MAN, I believe Salman is still in hiding. lol

    When it comes to depth perception I think I am pretty darn good although my old eyes ain’t what they used to be (and I know that nothing compares to the fine instrumentation that we have today) but, this images provides the clarity to show that NGC 7320 and the arc of blue babies are definitely foreground and not interacting with the other 4 in the background. Be nice if there was a gray scale of this same image; a lot easier to see depth. I’ll be headin for my foxhole now.

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