Desktop Project Part 18: X-raying the Pac-Man nebula

By Phil Plait | April 12, 2012 6:30 am

[Over the next week or two, I’ll be posting some of the many, many cool astronomical images I’ve been collecting and which are cluttering my computer’s desktop. These are all really cool pictures, and I’m glad I’m finally getting around to writing about them!]

One of my favorite types of objects are things that look like other things. So how can I resist writing about the Pac-Man Nebula, aka NGC 281? As for why it’s called that, duh. The image inset here (click to powerpelletenate) was taken using a telescope that sees optical light, the kind our eyes see.

The resemblance is obvious, isn’t it? If you’re my age or younger, than Pac-Man is pretty much all you can see there (and it’s not the only cosmic object to look like that, either). Of course, as an astronomer, I also see hydrogen (red), oxygen (yellowish-green), dust (black; it absorbs optical light), and evidence of star formation. Those finger-like things on the left are formed when young stars blast out fierce amounts of ultraviolet light, and eat away at the gas surrounding them. Think of them like sandbars eroding under a current. Still, all-in-all: this is clearly Pac-Man, albeit one over 9000 light years away.

But what happens when you look with telescopes that see other kinds of light? Like, say, infrared and X-ray? Then things look really different. Opposite, even!

What do I mean by that? Well, let me show you:

See! On the left is a combination of infrared and X-ray observations taken with Spitzer and Chandra, and I scaled the images to show the same field of view. Stuff that’s dark in the optical picture on the right glows brightly in infrared on the left — mostly warm dust. And the pink glow is due to X-rays from the very young, massive, and hot stars in the center of the Pac-Man’s mouth (ghosts?).

Looking at nebulae like this at different wavelengths tells us different stories about them. We learn more about how stars form, and what happens to the nebula itself as they do. Eventually, the stars in the center will explode, becoming supernovae, and will tear the nebula apart. And you know what happens to the nebula then, right?


Game Over.

Image Credits: X-ray: NASA/CXC/CfA/S.Wolk; IR: NASA/JPL/CfA/S.Wolk; Optical: NSF/AURA/WIYN/Univ. of Alaska/T.A.Rector

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CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (14)

Links to this Post

  1. 1000 Days of Infrared Wonders | Wired Cosmos | April 23, 2012
  1. Nigel Depledge

    Very cool.

    I was going to make a Pac-man related joke but you seem to have done them all.

    Of course, I had Vicmen, which was not Pacman at all, but a strangely similar game written for the Commodore Vic-20 (the Vic-20 was the predecessor of the Commodore 64). It ran in 3.5 kB of RAM. Can you even imagine a game running in less than a few hundred megabytes nowadays (except something simple like Patience)?

    Eeh, kids today, they don’t know they’re born.

  2. Russell


    Just what is “dust” ? Is it dirt? Is it the stuff I find under my couch?
    I think I once asked this question and someone answered it was organic molecules like carbon.

    Ohhh kaaayyy….lets say if I ran around a nebula with a bucket and caught a bucket full of “dust” what would it look like? Would it make my hands all black?

    Thank you!

  3. @ ^ Russell : It would take you an awfully long time to get together a whole bucketfull of dust from such a nebula – its still mostly vacuum. ūüėČ

    If your hands survived – I presume you’d be wearing spacesuit gloves – yeah, they may well be black but could also be other colours depending on the exact chemical composition of the dust in question. It may be silicate rich, may have organic molecules which get space-weathered into a reddish sort of goo at least on some outer solar system bodies if I recall right – or , yeah, could be black.

    To be honest I’m not really sure and would guess that it depends on the cloud in question. Good question. I’d suggest you try the BAUT forum with that one – link in my name here.

    Eventually, the stars in the center will explode, becoming supernovae, and will tear the nebula apart. And you know what happens to the nebula then, right?

    Well, the Supernova shock wave will push the debris together and disperse some of it clearing much of the area to create a bubble of emptier than usual space surrounded by loops of denser intergalactic material and possibly forming new stars but also destroying a section of the existing larger nebula, right?

    Oh and creating a whole new “crab nebula” style supernova remnant nebula too , right?

    Game Over.


  4. Messier Tidy Upper

    surrounded by loops of denser intergalactic material

    D’oh! I thought I’d written and intended to say “interstellar matter” there NOT “intergalactic” given this nebula is located in our Milky Way and NOT intergalactic space. Oops. (Blushes.) :-(

    @2. Russell :

    See :

    Hope you don’t mind but I’ve posted and asked your question in comment #2 – with link back here – on the BAUT forum. Hopefully they’ll be able to provide more info and a more satisfying answer for ya than my earlier (#3) best guess. :-)

  5. Charles J. Slavis,Jr.

    Phil I am now 3for 3…..I just read that bacteria is 98% certain the cause of 1976 findings from Mars…….I have now future projected us all to the points in time where the oil leak in the gulf was plugged……Bin Laden was killed…….and now to where alien life has been found…….can I get that million in quarters?……I have a change bank……What’s in your wallet?

  6. Charles J. Slavis,Jr.

    Damn! I really did it!

  7. Charles J. Slavis,Jr.

    I also said it will be funny if the Korean rocket fails……but didn’t project to it……I let the CIA do that…….

  8. Charles J. Slavis,Jr.

    I was a little worried about that alien life projection…….at 65 I was afraid I might future project us all beyond my statute of limitations…..

  9. Charles J. Slavis,Jr.

    I discovered future projection flying to Vietnam in 1969…….I visualized myself flying home and projected myself to that point in time……Of course it took a year in time and many adventures to get there……or was it just an instant?……Given eternity, a lifetime is but an instant, and a year is a small part of that instant………

  10. Charles J. Slavis,Jr.

    If space is infinite, then even our universe is a singularity compared to it……..

  11. Charles J. Slavis,Jr.

    Exactly how large is nothing?

  12. Charles J. Slavis,Jr.

    My definition of God is that which gave me existence……..everything eternally evolving….the unification theory of religion and science……

  13. Matt B.

    And in 20 years, you might have to explain the name “Pac-Man” every time you talk about the nebula, except that everyone too young to know will find it on the Internet in 20 seconds, using their thumbs, while calling it the Intartubez. /grumpy old man


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