Desktop Project Part 22: A black hole belches out a hurricane

By Phil Plait | April 16, 2012 6:30 am

[We’re in the home stretch of my Desktop Project: going through all the pictures on my computer’s desktop and posting one a day until they’re gone. Only a few left now…]

This is the only one of my Desktop Project pictures that’s not actually a picture: it’s an illustration. It’s still pretty neat:

[Click to Schwarzschildenate.]

This drawing shows the binary star IGR J17091‚ąí3624, which is actually a normal star in the clutches of a black hole. They orbit each other, and the fierce gravity of the black hole is drawing material off the other star. This matter doesn’t fall straight into the black hole, however. Because the two stars orbit each other, the material coming off the normal star has some sideways velocity (technically, angular momentum) which causes it to spiral around the black hole and form a disk called the accretion disk.

This disk is hot. Very way incredibly yikes hot: probably something like 10 million degrees Celsius (27 million F). The heat comes from lots of forces including magnetism and plain old friction as particles rub against each other pretty violently before The Final Plunge.

Stuff that hot emits X-rays, and this binary is blasting them out. What’s so very interesting is that astronomers studying this black hole found that something was absorbing X-rays from the disk. Their best guess is that this is vaporized iron blasting away from the disk in a kind of black hole wind, and it’s hauling butt: the material is expanding at a speed upwards of 9300 km/sec — that’s 5800 miles per second, fast enough to cross the US in less than the tick of a watch. Want another unit? That means the wind is blowing at a brisk 0.03 times the speed of light!

I love black holes. They’re many things, but one they aren’t is subtle.

Another thing they are is ironic: although most people think of them as being able to suck down everything, including light, they power the most luminous objects in the Universe. This black hole probably is small, a few times the mass of the Sun. But much bigger ones exist, with millions or even billions of times the mass of the Sun. Those are in the centers of galaxies, and can have so much material falling into them and heating up that they can shine brighter than all the stars in the galaxy combined! It’s not the black hole itself that’s glowing, but it’s the center, the engine, behind that raw fury.

And that wind may be more than bright: there’s some evidence that the mighty gale from a galaxy’s central black hole affects the overall state of the galaxy itself. It may be tied to the way stars form in the galaxy, and even the size of the galaxy itself. Mind you, even a black hole with a billion times the Sun’s mass is still only as small fraction of a galaxy, which might have hundreds of billions of stars! So while you might think of something like that as a monster, it’s actually more amazing to me that something so tiny can be so influential on such a huge scale.

Illustration credit: NASA/CXC/M.Weiss

Related Posts:

Star eaten by a black hole: still blasting away
S marks the spot
A tiny galaxy that hides a big secret
Black hole erupts in nearby galaxy

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (10)

  1. Man, you threw me there. I didn’t read the text first, and since all the other Desktop Project posts have been photos and not illustrations, my reaction was, “What?!?” (which I said aloud) “I’ve seen illustrations of that phenomenon, but never a picture. Where the eff did he get a PICTURE?!?” (the rest I thought silently to myself).

    So disappointed. heh, oh well.

  2. Ciaran

    Iron and irony, black holes have it all!

  3. Chris

    What is the biggest ball of Iron that could possibly exist? (ie. before some kind of gravitational collapse occurs)

    Can the math for this easily be done?

    I wasn’t sure where else on the internet I could ask this question apart from here :-)

  4. SabChi

    Mr. Astronomer,

    you should consider returning your degree, because of the degree of error when you say 10 million degrees Celsius = 27 million degrees Fahrenheit.. :)

    Just kidding, keep up the good work!

  5. OneofNone

    Oh, “Part 21” twice. Are you somehow superstitious on the ’22’? Just kidding ūüėČ

    It’s a great picture, thank you.

  6. Wzrd1

    @3, Chris, iron or any other element, it comes down to degeneracy. Pass that point and one collapses, first to a neutron star, pass neutron degeneracy and one collapses to a singularity.
    There is electron degeneracy, which arrives at the Chandrasekhar limit of 2.864 √ó 1030 kg (aka 1.44 solar masses). Then, one needs to consider proton degeneracy, that is still a bit theoretical and modeled off of electron degeneracy.
    Past neutron degeneracy, it’s theoretical, but estimates range from 1.5 solar masses to 3 solar masses, then collapse into a singularity occurs.
    THAT said, other things can cause the low end mass to be extended lower (such as sudden collapse of the stellar envelope, which then slams inward, increasing the core density immensely. Absorbing another star. Neutron star collisions, etc.

  7. OneOfNone (5): I just caught that! I fixed it. I wound up posting them in a different order than I originally planned, and forgot to fix the numbers. It’s actually rather amazing I got this far before having this happen. :)

  8. Brian Too

    “You were pumping iron,
    I was pumping irony.”

    – “Heaven Knows”, by Robert Plant

  9. This illustration reminds me that I don’t really understand gyroscopic torque/angular momentum.

  10. Wzrd1

    @#9, T Ray, don’t worry, there is magnetism to consider, just to further muddle the issue. ūüėČ


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