Temba, his spiral arms wide

By Phil Plait | September 3, 2012 7:02 am

Lying roughly 50 million light years from Earth is the magnificent spiral galaxy NGC 5033. Although that distance is a soul-crushing 500 quintillion kilometers, it’s actually relatively close by on the cosmic scale. Close enough that a lot of detail can be seen in the galaxy… and it also makes for a stunner of a picture:

[Click to darmokenate.]

This shot was taken by friend-of-the-BA-blog Adam Block using the 0.8 meter Schulman Telescope on Mount Lemmon in Arizona. It’s a whopping 13 hour exposure taken in near-true color.

It’s amazing what you can see in just this picture if you know what to look for. The spiral arms of the galaxy are fairly open, which is common enough, but the outer ones stick out a bit more than you might expect. The nucleus is very small and bright, more so than I’d expect for a typical spiral as well. Both of those things led me to expect this is an active galaxy, and that turns out to be the case.

Every big galaxy – ours included – has a supermassive black hole in the center. The Milky Way’s is 4 million times the mass of our Sun! In some galaxies, like ours, happily, the black hole is just sitting there. But in some there is gas actively falling into the hole. It spirals around and forms a very hot and very large disk, which glows fiercely as the matter is heated to temperatures of millions of degrees. They disk can blast out light from radio waves up to X-rays, and we say that the galaxy is "active".

A quick search of the literature didn’t turn up any measurements for the mass of black hole in NGC 5033, but it does confirm that it’s an active galaxy. Interestingly, the black hole is not located in the exact center of the galaxy! That’s very unusual, and indicates that NGC 5033 recently merged with another galaxy, probably a smaller one. It’s a cannibal! But then, most big galaxies are. It’s how they get big… and you’re living inside a big one, so there you go.

This may explain the wide arms on the galaxy as well; a collision and merger can distort the shape of the galaxy. Also, check out all the pink blobs along the arms: those are sites of furious star formation, the hot energetic massive young stars lighting up the gas around them. That also is common after a big collision.

Finally, one more nifty thing. You can see long ribbons of dark dust festooning the galaxy in the inner region. Dust absorbs light from stars behind it. But see how the dust looks like it’s only on one side of the galaxy, the half in the picture below the center? That’s an illusion, sortof. In reality there’s dust orbiting all around the center. However, there are stars above and below the disk of the galaxy, and the ones between us and the far side fill in the darkness a little bit, so the dust is less apparent. I’ve written about this before, and it does happen in quite a few spirals. Click the links in the Related Posts section below to see more gorgeous galaxies with this feature.

It’s funny how much information you can squeeze from a single picture! You have to be careful and not over-interpret it, and of course a lot of the things I’ve written here wouldn’t have been known without other observations of NGC 5033 using different telescopes and different methods in different types of light.

But even just one picture can tell you a lot. And in my opinion – and I tend to be right about these kinds of things – the wave of beauty that flows over you when looking at this picture is only enhanced by knowing more about the galaxy itself… and is boosted in no small way by the fact that we can know these things.

Image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona

Related Posts:

The dusty depths of a spectacular spiral galaxy
Patchwork galaxy
Virgos have beautiful eyes
Coincidental spirals

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (27)

  1. o i c what u did there.


  2. Paul Cutlip

    Sokath, his eyes uncovered.

  3. Brian Gonigal

    Is my browser being wonky or have you radically altered the layout of your blog page? The pic is now almost postage-stamp size small before it’s embiggened.

    (Never mind, when I hit “send” on this comment the page refreshed in its usual format.)

  4. Scott Oldfield

    Love the article title! Our dog’s name is Sokath. He’s blind, so I’m sure you’ll get the reference. :)

  5. Richard

    Man! Stunning picture!!! And each time I see such a picture I wonder how our own MilkyWay looks from the outside.

  6. Vonn D Lynn

    Nice Star Trek reference. Stunning photo how great we can see these images, thanks.

  7. Larry

    What is so cool about this picture, and countless other deep space photographs, is that if you look closely at the background, you see hundreds of more distant galaxies of all varieties.

    They always remind me of the line from Adam’s Hitchhikers Guide:

    “Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.”

  8. Kappy

    Picard and Dathon at El-Adrel

  9. @ Richard:

    Indeed. One of my favorite “gosh!” moments in science fiction is the scene in Arthur C. Clarke’s “Childhood’s End” where the Overlords show the hero a live view of the Milky Way from outside the galaxy.

    Makes me wish the sun weren’t so close to the middle of the Milky Way’s flat plane. Imagine what the view would be if we could see more of the disk, and not just a band of light across the sky.

  10. Chris

    I know everyone is focusing on the giant galaxy in the center. But also look and see how many little galaxies are dotting the picture. I see at least nine, but I’m probably being conservative. Many of the smaller dots are also probably galaxies and not stars.

  11. Before I started reading your posts, I didn’t realize I could actually do such things as darmokenate!
    Thanks for bringing big, deep space closer.
    Always fascinating.

  12. Frost Bite

    The galaxy is very beautiful, but the enlarged image…the background…soooo sweet. Ii’d love to see an enhancement of the backward “S” shaped galaxy in the upper right corner, possibly two galaxies combining?

  13. That last paragraph, to me at least, is the whole point of astronomy.

  14. Terry

    Phil, his eyes uncovered!

  15. This is a magnificent picture.

    But there is something very wrong indeed with so many of us having no trouble understanding an obscure Star Trek reference.

  16. Wzrd1

    I keep going into gimbal lock on the 0.8 meter telescope and a 13 hour exposure.
    The mechanics alone are humbling, as all vibration is damped or the image wouldn’t be clear.

  17. Hrdina

    NGC 5033 on the ocean

  18. Tara Li

    I’m finding the dim cloud at the very top of the enlarged picture fairly fascinating. Is that a nebula of some kind, or a “low-surface-brightness galaxy”, or what? It looks fairly close, whatever it is!

  19. Naomi

    Damn. Now I have to go rewatch Darmok.

  20. Lars Bruchmann

    I got the reference right away! No one ever else does though when I reference “Darmok”. Tamock, the River Tamock, in winter! One of the best eps ever. IMHO.

  21. Jon Hanford

    @ Tara Li(18),

    I was curious about this object too! A quick scan of the NASA/IPAC Extragalactic Database(NED) identified it as a magnitude 17.6 dwarf spheroidal galaxy, SDSS J131420.59+363407.9 (aka LEDA 166160). Although it appears partially resolved in the image, the redshift for this galaxy (z=0.0058) places it slightly beyond NGC 5033 (z=0.0029). Not much more is known about this little-studied dwarf galaxy.

    Also visible in this image are what appears to be a couple of galaxy clusters (or one elongated cluster) just to the lower right of NGC 5033. An even deeper image of NGC 5033 by Russell Croman shows them better: http://www.rc-astro.com/photo/id1187.html

  22. RyanH

    It may be just a trick of perspective, but to me this galaxy looks like the entire rear half of it is folded up at almost a 90-degree angle to the plane of rotation. It almost appears as if the middle of the galaxy is a bathtub drain that the galaxy is draining into. I’d say that’s a pretty strong visual cue that the galaxy has recently undergone a collision of some sort.

  23. The Bobs

    @18 Tara Li:

    I saw that too. I think it is a companion galaxy to the principal subject. It is similar in size and color to some of the larger clumps in the outer spiral arms.

  24. Brian Too

    I always thought that a civilization that based communication entirely on story and analogy, was pretty implausible. Especially for a technologically advanced civilization.

    None of that detracts from the imagination and wonder of the ST:TNG episode. Nor does it detract from a terrific blog posting here.

  25. Mike

    Phil and Mike at the blog.

  26. [holds up one hand]

    Temba at rest.

  27. Messier Tidy Upper

    I love this! The image, the informative write up and the Star Trek allusion in the title. :-)

    Whatever happened to galaxy Mondays, btw, BA? I liked that. Hope & request you bring that back, please.


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