Desktop Project Part 25: Chaos in a galactic nursery

By Phil Plait | April 19, 2012 6:30 am

[The Desktop Project is my way of a) forcing me to write something every day by 2) posting a brief article about all the astronomical images I’ve collected on my computer’s desktop. I’m actually getting ahead of the onslaught, so I’m thinking this week may see me catching up!]

M82 is classified as an irregular galaxy — that is, one that has no overall shape, but instead a weird, splotchy configuration. When you see a picture of it, you’ll see why… and Adam Block of the Mt. Lemmon SkyCenter has a great one!

See what I mean? You can see an underlying galaxy there, but all that red stuff certainly makes it look, well, irregular.

… but wait a sec. If you look at just the galaxy (the blue stuff), it bears more than a striking resemblance to a run-of-the-mill — if heavily warped — edge-on spiral galaxy. And all that red stuff appears to be emanating from the center, as if its being blown from the core of the galaxy like a giant wind!

This, it so happens, is exactly what’s going on. And the reason is that M82 is prolifically fecund: it’s undergoing an intense burst of star formation, creating stars at a rate far exceeding that of the Milky Way.

Young stars can be extremely energetic, blowing out tremendous winds of gas. All that red stuff is actually warm hydrogen, blasting away from the center of the galaxy where all that star birth is occurring. In fact, there may be as many as 200 clusters of stars in the core of M82, in total containing tens of millions of stars. That’s a lot of engines to drive out that gas. No wonder astronomers used to think the core of the galaxy was exploding! But now we know it’s the opposite: it’s not the deaths of thousands of stars creating that chaos, it’s the births of millions of them.

So what caused this incredible profusion of new stars? M82 lies close to a bigger spiral galaxy called M81, and there’s some indication they are gravitationally interacting. A near collision between the two some time ago may have stirred up the gas in M82, causing it to drop to the center of the galaxy where it became the raw material to build stars.

You might think a collision between two galaxies would result in nothing but calamity. But again, the opposite is true! In astronomy — in everything, really — you have to be careful about your presuppositions. The Universe doesn’t care very much what you think, and will continue to behave according to the laws of nature. We’re the ones who have to change and adapt to what it’s telling us.

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

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Attack of the galactic subatomic particles
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In galactic collisions, might makes right
M81, up close and personal
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Sometimes a cigar galaxy is just a cigar galaxy

CATEGORIZED UNDER: Astronomy, Pretty pictures
MORE ABOUT: Adam Block, M82, star birth

Comments (8)

  1. “The Universe doesn’t care very much what you think, and will continue to behave according to the laws of nature. We’re the ones who have to change and adapt to what it’s telling us.” Well said.

  2. mike

    Nice image. Definitely one of my favorite galaxies – both because it looks so cool framed together with M81 in a small telescope, and also because of all that seems to be happening there (including “apparently superluminal” microquasars )

  3. Greetings and Salutations.
    First off, I agree 100% with Sherry Austin. While the same thought has been expressed by others, in somewhat different words, that is a very cogent way of putting out how the Universe works. For that matter it works whether one is speaking of the Macro scale of Galactic Interactions or the Micro scale of some of the odd interactions of sub-atomic particles.
    As for the picture that is the center of the thought here…I have to say that the higher resolution pictures do make it clearer that the plumes of warm hydrogen are coming from inside the spiral galaxy. Years ago, when I first saw less detailed images of this event, it looked to me as if this was more on the order of some sort of plume of the gas superimposed on the image of the galaxy. More information is always better than less information, even if it DOES force one to reconsider basic beliefs…
    Pleasant Dreams
    dave mundt

  4. Charlie

    How warm are we talking when you say “warm hydrogen”? I assume it is still pretty cold compared to our comfy 20 C.

  5. Greetings and Salutations;
    Well, it is my understanding that the gases have been heated to several million degrees….but…the fact that their density is so low means that it is not exactly WARM in the middle of the cloud. Got to remember that “temperature” is a function of the amount of energy imparted to the molecules, so, a Hydrogen atom bouncing around at a high speed because of the energy imparted to it from the radiation produced by star formation, is “warmer” than one that is just barely moving because it has no external source of energy…
    IANAP, so, if Dr. Plait or one of the many other readers who are far more knowledgeable about the subject want to chime in, I would welcome the input!
    pleasant dreams
    dave mundt

  6. JR

    To be nitpickily specific: starburst driven outflows receive a significant fraction of their energy and momentum from Supernovae, not just from stellar winds. From Veilleux’s 2005 review of galactic winds:

    “In general, stellar winds are important only in young (10^7 yr) starbursts that form many high-mass (60 Mo) stars in a metal-rich (Z>Zo) environment. In any other situation, SN explosions dominate the energetics of the ISM. SN explosions usually dominate by the time GWs develop, but stellar winds may be important in superbubbles.”

    Links for further reading:

    References for people who like that sort of thing
    (Besides the 1700 articles about M82 itself):…493..129S…711..818S…721..505R

  7. Infinite123Lifer

    “The Universe doesn’t care very much what you think, and will continue to behave according to the laws of nature. We’re the ones who have to change and adapt to what it’s telling us.”

    Hey wait, I thought I was part of the Universe? 😉

    Oh, you mean the rest of the Universe doesn’t care what I think . . . very much. :) Indubitably Dr. Plait, indubitably.

  8. Infinite123Lifer

    I suppose taking me away from the Universe is akin to subtracting 1 from infinity, though it may show up in the calculation, its/I am more of just a nuisance 😉


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