The Milquetoasty Way

By Phil Plait | February 17, 2011 7:01 am

I write about spiral galaxies here, and when I do it’s usually because they’re unusual. They’re really big, or small, or violent, or forming lots of stars.

So how about one that’s entirely normal? But don’t let that fool you: it’s still gorgeous. Take a gander at NGC 2841, a perfectly normal spiral galaxy as seen by Hubble:

Breathtaking, isn’t it? Click it to galactinate, or grab the super-dooper 3400 x 3000 pixel high-res version.

NGC 2841 is about 45 million light years way. That kinda sorta close, but not too far, keeping with our theme of averageness. It’s not particularly extraordinary in any way — assuming that any time you see an object tens of thousands of light years across and possessing a hundred billion stars, you’re seeing something ordinary. This type of galaxy is called flocculent: with lots of short arms instead of a two or three long, grand, majestic ones.

It’s forming stars, but not many. Those blue patches are where stars are being born, and they seem small, well-behaved, and scattered evenly across the galaxy’s disk. Everything about this galaxy is, well, polite. It doesn’t have enormous star-birth factories, it isn’t colliding with another galaxy, it doesn’t have weirdly-shaped arms.

In fact, I was so suspicious of its normalcy that I did some searching, and honestly didn’t see too many papers about it. This smaller image is from Spitzer Space Telescope, and shows the galaxy in infrared (again, click to embiggen). That highlights dust and star formation, and while again it’s very pretty, there’s not much going on. The galaxy is definitely forming stars; you can see the clumps of dust glowing in the IR. But no big patches, no giant glowing regions. The inner part in the visible Hubble image appears smooth and a little boring, and the same is true in the IR.

There’s a nice nucleus, but it’s small and not terribly bright. There’s a supermassive black hole there, as there is in every galaxy, but it doesn’t appear to be actively feeding right now. It’s a LINER — low ionization nuclear emission-line region — meaning atoms near the center are being excited by the action near the core, but not a lot. Some galaxies pump out huge amounts of radiation from their centers, and others are quiet (like the Milky Way). This one is somewhere in between.

So if this galaxy is so steady and serene, why observe it? Well, for exactly that reason. If you want to study why galaxies undergo bursts of star formation, you have to understand galaxies that aren’t. You can think of them as a control group if you’d like. Something against which to compare the more gregarious galaxies.

Still, its beauty cannot be denied. The Hubble image is really something. The gently clumpy pattern to the arms reminds me of low clouds over the Great Plains of the US, seen from an airplane (something I’ve witnessed countless times). It’s relaxing. Gentle, lovely.

It goes to show you: in astronomy, even a run-of-the-mill, average, and not-so-special galaxy is still an object of great and exquisite elegance.

Image credits: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration Acknowledgment: M. Crockett and S. Kaviraj (Oxford University, UK), R. O’Connell (University of Virginia), B. Whitmore (STScI) and the WFC3 Scientific Oversight Committee.; Wikipedia, NASA/JPL-Caltech/


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CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (55)

  1. A.

    Beautiful! Or beautifully average.

  2. Gary Ansorge

    Watch the pretty galaxy, rotating slowly, nothing much going on here, sleep,sleep,,,OMG,WHAT’S THAT?

    Even a sleepy back water has the occasional super nova,,,

    ,,,now, where’s a small galaxy we can toss its way (can you say cannibal?).

    Kinda reminds me of Cartersville, Georgia,,,sleep,sleep,,,

    Gary 7

  3. Can you say flocculent in a family blog?
    Oh. OK. Never mind.
    Looks like a nice place to live.

  4. OtherRob

    Ordinary or not, I don’t I’ll ever get tired of pictures like this of spiral galaxies.

  5. Messier Tidy Upper

    Breathtaking, isn’t it?

    Yes.

    Yes it is. Superluminous image there – a new favourite of mine. Thanks. :-)

    Very symmetrical galaxy, NGC 2841, isn’t it? If It lacks a nickname might I suggest the Perfect circle oval galaxy for it? ;-)

    It goes to show you: in astronomy, even a run-of-the-mill, average, and not-so-special galaxy is still an object of great and exquisite elegance.

    Um, but.. isn’t a run-of-the-mill average galaxy actually a dwarf elliptical or something like that? Aren’t most galaxies – like most stars (& most planets?) typically the smaller fainter, less spectacular variety? ;-)

  6. So it is the Canada of galaxies?

  7. Jon Hanford

    This image of NGC 2841 is also included in the Hubble Heritage Project, which includes the four monochrome images used to create this fantastic view: http://heritage.stsci.edu/2011/06/original.html

    It’s easy to spot the small, hot star forming regions of the galaxy in the F336W (U-band) image of NGC 2841. These are also seen to a lesser extent in the F685W (H-alpha + [NII]) narrowband image.

  8. Chris A.

    [2 cents]”Gregarious?” I think I would have gone with “ostentatious” or, perhaps “ebullient.”[/2 cents]

  9. Sometimes I like the boring galaxies. They just seem like friendly places. I can enjoy the beauty in the symmetry and color without having a lot of science shining in my face. There are times when it’s just nice to enjoy the beauty of complex things.

  10. Oscar Ferro

    You should have said ‘Click to flocculently enlarge’.
    I can’t believe you missed that one!

  11. AJKamper

    Wait. Spirals are only 15% of all galaxies. A spiral, by that definition, isn’t average at all.

    I want to see you try to opine about the beauty of an elliptical galaxy next time. “Hey, look! A blob!”

    Like #5 said, this is hardly representative.

  12. Michel

    I love green blobs.

  13. A couple doses of Beano would take care of that flocculence.

  14. Ditto on the lit search…. couldn’t find anything recent that really focused on it especially. It’s unappreciated, I say!

  15. SMedlin

    It may never be on the cover of a journal, but it does have a certain galaxy-next-door quality to it that’s very appealing.

  16. DrBB

    Here in the Local Group all our galaxies are above average!

  17. Theron

    It would appear to my untrained eye that there is a tight densely packed cluster of stars in the middle, and then a vast ring fairly empty of stars before you get to the arms. What’s going on there?

  18. JD

    A beautiful island that is aging gracefully upon the Universal seas!

  19. Grrr, Shane beat me to the joke. That’s what I get for being in meetings all morning.

    Well, it was about time I put in a new desktop. Thanks. :)

  20. Every time I see a galaxy i wonder how many civilizations are look back, how many worlds are full of life…. I feel as if I was born too soon.

  21. Jeremy

    “NGC 2841 is about 45 million light years way. That kinda sorta close, but not too far, keeping with our theme of averageness.”

    “A galaxy far away…but not ‘far far’ away, we can’t afford that many carbon offsets.”

  22. Regner Trampedach

    Theron @ 17: The nucleus, “a tight densely packed cluster of stars in the middle”, of the galaxy is pretty (and) obvious, but I don’t see your “vast ring fairly empty of stars”. Remember, the yellowish white light you see, tapering off from the nucleus, is light from the stars. The dark orange to brown to black is cold gas and dust that blocks our view of the stars. The blue patches are merely where new stars are formed and the pinkish/red patches are hot clouds of gas (HII regions – ionized hydrogen regions). The vast majority of stars show themselves in yellow and cover the whole image, corner to corner, although the bottom-left and top-right corners are rather sparsely populated (farthest from the nucleus) – but it is still far from empty, black, inter-galactic space.
    Oh, and the two bright orange stars at the lower center are local stars from our Milky Way. The left one has clear diffraction spikes, which can only be seen for the fainter star in the super-dooper hig-res version of the picture.
    Cheers,
    Regner

  23. Something I’ve been wondering for a while now…

    If a galaxy can be tens, or even a hundred, thousand light years across, doesn’t that mean that the “far” side of the spiral that we see isn’t “in sync” with the “near” side? In other words, the shape we see is not the real shape, since we’re seeing those stars in the back where they were tens of thousands of years earlier than the stars in front.

  24. @SMedlin,

    It may never be on the cover of a journal, but it does have a certain galaxy-next-door quality to it that’s very appealing.

    Yes, but you just know that those magazine cover galaxies have been airbrushed to thin out their eliptical arms or enlarge their central-black-hole bulges. They probably had galactic cosmetic surgery done too. A smaller galaxy implanted here or there. This galaxy’s beauty is all natural!

  25. Ken B,

    Well, it would depend on how that galaxy was facing us. If both ends were the same distance, then we’d be seeing the ends at the same point in time. But if there was an angle involved, then we would be seeing the galaxy across a hundred thousand year (or so) span.

  26. That is an absolutely gorgeous picture. Thanks for sharing and explaining it.

    Out of curiosity, why are star-forming regions specifically active in infrared? Is it due to the coalescing process itself, or the nuclear fusion “bootstrapping” processes exciting molecules right in that band prior to ignition, or something else?

  27. Meanwhile, someone in NGC 2841 is looking in OUR direction and thinking “Gee, what an average looking spiral galaxy!”

  28. NoAstronomer

    @Jerome

    AFAIK star forming regions radiate strongly in the infrared because for several reasons:

    1. In many cases we see star forming regions are ‘dusty’ areas that are being compressed by external influences (eg a nearby supernova) so that causes the dust and gas to heat up.

    2. Yes, as the pockets of dust and gas start to collapse they will heat up through the release of gravitational potential energy.

    3. Stars that are forming in the region will tend to heat the surrounding dust and gas that did not actually fall into the new star.

    I’m sure someone will jump in to correct me if I’m wrong.

  29. dcsohl

    I went and downloaded the super-dooper high-res image, and noticed just around the core some dark circles, or I should say dark arcs since there are breaks in them. What are those? Phil? Anyone else?

  30. Joseph G

    Wahhhhhh
    There really needs to be an emoticon for bug-eyed wonder. I’d use it a lot :)

    Makes me wonder if somewhere, 45 million light-years away, someone is looking at our Milky Way…
    “And here’s a lovely barred-spiral galaxy. It’s pretty large as galaxies go, but not quite so much as it’s neighbor. The core region is fairly quiet – its central supermassive black hole seems to have cleared its immediate area, for now. All in all, it’s impressive, but not too extreme in any particular aspect. We can learn a lot about more active galaxies by studying quieter ones, like this one here.”

  31. Truly a stunning image.

  32. @NoAstronomer: Ah, that makes sense, thank you. For some reason, while I can readily grok the process that goes on with absorption/emission energy and its underlying reason: electrons moving between energy levels, I’ve never thoroughly understood the reason behind the black-body temperature-as-infrared EM radiation phenomenon.

  33. David

    I like how the clouds of dust are uniformly distributed over the arms of the galaxy; looking like a spider’s web draped over it. No breaks or holes. Does anyone know if there’s an image that shows the whole galaxy and not this closeup? I’d like to make it my desktop.

  34. Joseph G

    One question about these images of galaxies I’ve always wondered about – are there any stars that are actually bright enough to see individually (main sequence stars, not supernovae)? I see a lot of points of light, but some are probably foreground stars, brightly lit clumps of gas and dust, etc. It’s amazing to contemplate the scales involved – those tiny blue dots representing the star-forming regions are probably tens or hundreds of light-years across.

  35. Joseph G

    @NoAstronomer: I was reading about that recently, and it’s amazing how easy it is to underestimate the power of that gravitational potential energy being released. If I understand correctly, protostars can shine as bright as main-sequence stars for hundreds of thousands of years before they ever initiate fusion, simply from the heat caused by all that collapsing matter colliding.

  36. Joseph G

    @24 TechyDad: *snerk*
    Those silicon supernova remnants just never feel quite right :P

    I can’t find the post for some reason, but someone was looking for more complete images of this galaxy? Here’s what I’ve found (that are suitable for wallpaper, anyway).
    http://www.wallcoo.com/nature/2009_Landscape_1680_Desktop_03/wallpapers/1600×1200/Spiral%20Galaxy%20NGC%202841.jpg

    http://www.not.iac.es/general/photos/astronomical/extragalactic/NGC2841.jpg

    http://img.photobucket.com/albums/v125/SaeedKhan/NGC2841-SpiralGalaxycanbefoundinthe.jpg

    Of course, none of them have the detail and the same multi-spectrum false color layers that this one does.

  37. Mike C

    I’m still confused as to why the center is giving off light…shouldn’t it be black, if it’s a black hole?

  38. Joseph G (#30):

    Makes me wonder if somewhere, 45 million light-years away, someone is looking at our Milky Way…
    “And here’s a lovely barred-spiral galaxy. It’s pretty large as galaxies go, but not quite so much as it’s neighbor. The core region is fairly quiet…

    Well, except for the fact that they would be seeing our galaxy as it was 45 million years ago, when things may have been quite different.

    Mike C (#37):

    I’m still confused as to why the center is giving off light…shouldn’t it be black, if it’s a black hole?

    You’re not seeing the black hole. You’re seeing all of those stars surrounding it.

  39. Steve

    Nicely said BA. This is why I keep coming back.

    Is the light near the center from stars surrounding the black hole?

  40. Steve

    Ken answered it right before I asked. Thanks.

  41. RwFlynn

    I think I’ve got a new wallpaper to admire. :)

  42. Joseph G

    Regarding the visibility of black holes, it’s worth remembering how compact they are. You can calculate the size of the event horizon of a black hole (its Schwarszchild radius) if you know its mass (interestingly, any mass has a Scharzschild radius – if you compress it to that radius or smaller, it becomes a black hole; it’s both a measure of the event horizon of a black hole and the compactness required to create said black hole). I’m lousy at math, but awhile ago I remember finding a nifty calculator that lets you calculate a Schwarzschild radius for any mass. For our sun, that radius would be less then 3 kilometers! For a supermassive black hole of over 4 billion solar masses, like the one in the center of the galaxy is expected to be, IIRC, the radius comes out to something like twice the (actual) radius of our sun – big for a black hole, but not big at all in cosmic terms.

  43. Joseph G

    @Ken B: That’s true, though even 45 million years ago, things probably weren’t that different. That’s not that long on galactic scales :)
    I wonder, if our galaxy were an active galaxy, would it affect us? Active galactic nuclei can be pretty darn scary-powerful, but then, we are at a comfortable distance from the core, and the jets caused by the accretion disc around the SMB probably wouldn’t be pointed in our direction, right?

  44. Meander

    That is an absolutely amazing picture, thank you. Although I think I melted my brain trying to imagine how big it actually is…

  45. Radwaste

    Well, while you’re looking at this pic, remember something Phil posted before: our own Sun, while it’s larger than average around these parts, would be tough to see beyond about 60ly. Now think of the individuals and groups you can see a a ways off, like this one. The bright stuff you’re seeing is only a fraction of that galaxy’s stellar population.

  46. Joseph G

    @46 Radwaste: Space certainly has a way of ****ing with your sense of scale :)
    Something can be unimaginably vast, yet is dwarfed into microscopic insignificance by something else, which itself, although just mind-numbingly enormous, is even tinier then the first thing on the scale of this other thing over here, and so on :P

  47. I think you should have said “click to enfloculate”. :)

  48. callcenterhero

    I don’t think it’s possible for us to actually comprehend the size of space and everything around us. I feel as if my brain is programmed to focus on the length of a mile, when thinking in terms of the vastness of space while it does blow my mind, I dont think its possible to grasp just how small we are. I appreciate a good mind blowjob though, and I can count on astronomy to do this for me on a daily basis.

  49. Doug

    I recall years ago someone tried to organize a symposium on “normal” galaxies. He found there was no such thing. If looked at closely, every galaxy has SOME peculiarity. That’s why there was a symposium on “Nearly Normal Galaxies.”

  50. CB

    @ Doug:

    I recall years ago someone tried to organize a symposium on “normal” galaxies. He found there was no such thing. If looked at closely, every galaxy has SOME peculiarity. That’s why there was a symposium on “Nearly Normal Galaxies.”

    Which means that if you ever did find a completely normal galaxy, its unpeculiarity would itself be peculiar, its normality abnormal, thus at best qualifying it for “nearly normal” status.

  51. Maybe we should call this galaxy “Serenity.”

  52. was no such thing. If looked at closely, every galaxy has SOME peculiarity. That’s why there was a symposium on “Nearly Normal Galaxies.”

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