Snapshot of galactic doom

By Phil Plait | March 16, 2009 11:16 am

Take one part Spitzer Space Telescope, one part Hubble Space Telescope, and two galaxies. Shake well, bake covered for a few million years, and get this:

Click to embiggen, or go here for access to much higher res images!

Coooool.

This is NGC 6240, what used to be two galaxies but are in the process of becoming one. We see colliding galaxies all over the sky, but what makes this one special is the timing and its location.

Collisions take hundreds of millions of years, starting from the first tentative approach to the complete merging of the two. But the different steps of the process take different amounts of time. The initial approach takes a long time, for example, so we see lots of those. The actual physical merging also takes many millions of years, so we commonly see that as well. But while the outer parts of the galaxy are interacting, so are the cores. The time between the outer parts settling down and the inner parts doing their thing can be fairly short. NGC 6240 is right now at the moment in its life where the two galaxies have started to merge, but the cores of the two are still distinct.

Also, the farther away we look, the more volume of the Universe we see, so the more galaxies we see. In the distant Universe we do see galaxies in this stage, but they are so far away that details are unclear. NGC 6240 is only 400 million light years away, which is a ridiculously long way in human terms, but close enough in cosmic scales that Hubble and Spitzer can see those details.

The outer parts of the galaxy are still messy, churned up by the violence of the collision. Huge gas and dust clouds have collided, which triggers an immense burst of star formation. Newborn stars create a lot of dust — giant organic molecules that are very efficient at absorbing the visible light Hubble detects. However, warm dust emits infrared light, and Spitzer can see that.

So in the Hubble image we see the stars and gas tossed all over the place, and the chaotic dust (in red) detected by Spitzer. Combined, the two images tell a tale of what a pair of galaxies is like just before their cores start to merge, a snapshot in an instant of a catastrophic event.

… and in a few million years, the fireworks will really begin. All big galaxies have a supermassive black hole in their hearts, and the two bruisers in this pair will start to work their magic as well. The cores will combine, and the gravitational wake of the two black holes interacting will make the previous merging process seem like a gentle breeze. The gas and dust in the center of the merging monsters will become incredibly turbulent, mixed violently and suddenly, creating a vast wave of star formation. A huge amount of energy will blast out of the core, and get absorbed by the dust there. It will convert that high energy radiation into infrared, pouring out the invisible light, and NGC 6240 may become a ULIRG, an ultra luminous infrared galaxy.

It will pose no threat to us at its vast distance, but we’ll have a great view of this step in a galactic merger as well. Too bad we have to wait several million years for it. So for now we’ll just have to be satisfied with catching this merger in the act. There’s still plenty to learn from it.

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (52)

  1. Purdy!

    NASA should release more Spitzer/Hubble composites–they’re frackin’ beautiful!

  2. scotth

    I *love* stuff like this.

    I also love the promise humanity getting to watch the whole drama unfold over the next few million years. Now, humanity just needs to keep itself together and keep watching.

    I see all this work so many of us do to stamp out superstition and unthinking as contributing to this great and long-playing cause.

  3. Where’s the kaboom? There was supposed to be an earth-shattering kaboom!

  4. This highlights a sort of tragedy of the human condition in this day and age. We’re at the level of development and knowledge that we can see these wonderful things happening, and we also know that we (individually) will never see more than brief glimpses of anything at one time. We can’t see the galaxies merge in our lifetimes, we can only hope to catch enough snapshots of enough of these sort of interactions to be able to piece together a picture.

    I’m sure it’s perspective talking, but it seems the 19th-21st century lives are (more than most times in the past) populated with the wonder and fantastic amazement of new invention, achievement, and discovery, but plagued with the short life and knowledge that we’ll die before so much of “the future” unfolds. It doesn’t seem that average Joe of the 16th century had a vision for the broad horizon we’ve developed in the last hundred and fifty years. Maybe we always had the hope as a species to partake in the magic of the future, but it seems particularly pointed now that it isn’t magic, and so much of the future is see-able even if we can’t yet see the path we’ll take to get there. It’s a sort of tragic irony that those who have a “hope for eternal life” have a vision of that as something largely unchanging and static (even those not in the “harps and clouds” view of it), instead of a view that would allow for enjoying the constant change of discovery and development that, to me, would be the beauty of extended life.

  5. Mary, you stole exactly what I was going to say! :)

    And Charles and scotth, I couldn’t agree more.

  6. Chris P

    But this magnificence wasn’t in the Bible I read. I mean, everything happened 6 thousand years ago. There MUST be something wrong with the math if you guys are extrapolating back millions of years.

    Wasn’t it just as simple as “Shit happened”

  7. Rob

    Sooo.. not a good vacation spot then?

  8. Todd W.

    Phil, off topic, but do you have any updates on The Skeptologists?

  9. Chris

    “… and in a few million years, [we will see] the fireworks [that are happening right now]”

    Fixed

  10. Phil may find odd my dropping in on his blog with a posting related to a galactic merger, since he knows my (primary) interests are in circumstellar protoplanetary and debris disks and the environments where exoplanets are born. That said, NGC 6240 is probably my favorite galaxy (excepting perhaps the Milky Way, but only because I live here), or as is obvious from this post more properly “galaxies” (plural). So much so, that I actually have done previous Hubble work on NGC 6240 myself, in collaboration with a team using the Keck observatory with adaptive optics. So, I would offer a slightly different recipe to Phil’s as: “Take one part Spitzer Space Telescope, TWO partS Hubble Space Telescope (the second using it’s Near Infra-red Camera and Multi-Object Spectrograph), one part Keck, and two galaxies…” to get an even “better” picture of what is going on in the global environment on large scale (ala the Spitzer+HST/optical) and nuclear/circum-nuclear (HST/near-IR + Keck) scales. With HST/Keck we have seen, and discussed a population of “super star clusters” evidently triggered into formation in the circumnuclear regions of the merging galactic cores – a near instantaneous burst of stellar populations in a rather exotic environment. For those with interest the details are here:
    http://nicmosis.as.arizona.edu:8000/PUBLICATIONS/NGC_6240_APJ_2.pdf
    But, the “pretty picture(s)” of the merging nuclei themselves, in the “core” of NGC 6240 is found in our first paper here: http://nicmosis.as.arizona.edu:8000/PUBLICATIONS/NGC6240_APJ.pdf
    In particular Figure 8 (but also others). Well, they may not be AS pretty as spectacular Spitzer+HST image just released (unless you are an astrophysicist). But, to me, this new combined-facilities release with work previously done underscores just how symbiotic such observations at different wavelengths, taken with different telescopes and instruments really can be. Let’s get all we can from the Spitzer “Warm Mission” plan and for full success of Hubble Servicing Mission 4!

  11. Thanks for rubbing salt in my wounds Todd W… :( Apparently CENTAF is against the idea of The Skeptologists since all websites associated with that show are blocked because they are “Educational”… (Yeah, my irony meter pegged on that category…)

  12. Todd W.

    @Larian

    Sorry. The Skeptologists web site doesn’t have any information on where the show stands beyond that principal photography has wrapped, and that was quite a while ago. So, no news there.

  13. dre

    Now I’m hearing Ben St#!n’s voice:

    “Ulirg? Ulirg? Ulirg?”

  14. Glenn, it’s no more odd than finding out Saul Perlmutter studied Nemesis!

  15. Pareidolia be damned…that’s the Starship Enterprise!

  16. This is ridiculous, because there’s no such thing as gravity. Or pie.

  17. I’m confused by some of the terminology. Is Galactic Core (GC) the same thing as Active Galactic Nucleus (AGN) or are these two totally different things. There seem to be several concepts running around and I can’t keep them straight:

    1.) central bulge

    2.) galactic core

    3.) galactic nucleus

    @BA “and in a few million years, the fireworks will really begin. All big galaxies have a supermassive black hole in their hearts, and the two bruisers in this pair will start to work their magic as well. The cores will combine, and the gravitational wake of the two black holes interacting will make the previous merging process seem like a gentle breeze. The gas and dust in the center of the merging monsters will become incredibly turbulent, mixed violently and suddenly, creating a vast wave of star formation. A huge amount of energy will blast out of the core”

    I’m also confused about what the fireworks are. I thought the gas from galaxy B getting sucked into galaxy A’s black hole is what caused the fireworks to happen. I doubt star formation can compete with the direct black hole action since nuclear fusion can convert only 0.7% of mass into energy whereas black holes can extract up to 40% of mass into energy.

  18. Jdhuey

    “Also, the farther away we look, the more volume of the Universe we see, so the more galaxies we see. ”

    I always have a hard time conceptualizing this space-time expanding universe thingie. I keep running up to this seeming contradiction and I can’t think my way out. We have the above quote from the article and to my mind it is self-evidently true; however, as we look further out we are also looking further back in time and, since the universe is expanding, that older universe is smaller than the current state of affairs. So, if we look out we see more volume and a smaller volume. If someone has an explanation (reconciliation?) without going into tensor calculus (well, I can follow tensor calculus even if I can’t DO tensor calculus) I would be grateful.

  19. Jdhuey

    Well, since I’m in a question asking mood, I’ve got another to toss out. I can easily see that the merger of the galaxies and the galactic cores will release a tremendous amount of energy but how would that affect a planet orbiting a star that is, say, out near the boondocks of one of the galaxies? Are we talking energy levels that boil away atmospheres or just enough energy to make a needle on an instrument kick up a smidge?

  20. IVAN3MAN

    Mary Mactavish:

    Where’s the kaboom? There was supposed to be an earth-shattering kaboom!

    Larian LeQuella:

    Mary, you stole exactly what I was going to say!

    That is because sound is a mechanical vibration and cannot travel through the vacuum of space; it requires a medium, e.g., solid, liquid, or gas, to transmit. ;-)

  21. IVAN3MAN

    Hey, Tom Marking. I have noticed that you have been frequenting Oil-Is-Mastery’s blog and arguing with him. I figure that his mind-set is probably a curiosity to you as it would be to psychiatrists in general, but I have to warn you that, amongst all the doctorate professions, psychiatrists have the highest suicide rates. You have been warned! :-)

  22. Liz

    Send not to ask for whom the bell tolls … Andromeda here we come!

  23. @IVAN3MAN “Hey, Tom Marking. I have noticed that you have been frequenting Oil-Is-Mastery’s blog and arguing with him. I figure that his mind-set is probably a curiosity to you as it would be to psychiatrists in general, but I have to warn you that, amongst all the doctorate professions, psychiatrists have the highest suicide rates. You have been warned!”

    Actually, I didn’t know much about EU theory before so I thought I would investigate it. I figured they couldn’t all be nuts if their founder, Hannes Alfven, won the Nobel Prize. It turns out Oil Is Mastery is steeped pretty deeply in woo – he makes Anaconda look sane which is saying a lot frankly. I’ve learned some very interesting things at OIM:

    1.) The earth is expanding, not the universe

    2.) The mass of the earth has never been measured and never will be

    3.) If you performed the Cavendish experiment in a Faraday Cage you would get radically different results

    4.) NASA is covering up evidence that gravity doesn’t exist (even though the experiment which “demonstrated” this was published on a NASA web site)

    5.) The former Atlantis is what we call today Antarctica. If you dug beneath the ice sheet there you would uncover a wonderful advanced civilization which perished in 9,600 B.C.

    6.) Venus used to be a comet and assorted other Velikovskianisms

    .
    .
    .

    So, in short, all the woo you could use except for the Maya doomsday stuff and Nibiru which are probably in there somewhere. According to OIM, he is going to write a book. May I suggest a title? How ’bout: Woo from the Skies – These are the ways you will get screwed. :)

  24. @Tom Marking “Actually, I didn’t know much about EU theory before so I thought I would investigate it.”

    And now, for the moment we’ve all been waiting for eagerly these past few weeks
    .
    .
    .
    Anaconda’s EU explanation for Cygnus X-1
    .
    .
    .
    (drum roll)
    .
    .
    .
    A: Cygnus X-1 is an X-ray emitting white dwarf that emits no optical light

    ROFLMAO. I kid you not. That is his explanation which I waited one month for. :)

  25. arroyo

    it looks like the egyptian eye thing thats pretty cool

  26. J Earley

    If you look carefully in the hi-rez image, there are some (very distant) spirals. I love that sort of thing because it lends a bit of perspective as to the scale of space.

  27. IVAN3MAN

    @ Tom Marking,

    Yeah, Anaconda stated exactly the same rubbish about Cygnus X-1 at Universe Today on the “Hubble Finds Evidence of Dark Matter Around Small Galaxies” thread there. :roll:

  28. P.S. Tom Marking, for your convenience, I’ve provided a direct link to the above mentioned thread at Universe Today via my name.

  29. I didn’t state there was no light, but that at 6,000 light-years, and an intervening dust cloud, that light simply doesn’t reach the Earth.

    But hey, misstate what I wrote and set up a straw man, you guys do that all the time.

  30. Davidlpf

    @Tom Marking
    The electric universe people kind of suck you in like a blackhole.
    (Well at least Nathan is not here to tell us the defination of irony.)

  31. Davidlpf

    @Anaconda how do you know it is white dwarf.

  32. IVAN3MAN

    Re: Anaconda.

    Speak of the Devil…

  33. IVAN3MAN

    Hey, Todd W., guess who’s here?!

  34. Todd W.

    I figured it was only time before he showed up. You guys’ve been mentioning his name quite a bit. I wonder if he’ll finally answer my questions in the roar of the centaur thread… I won’t hold my breath.

  35. Jojo

    I’m curious. When galaxies merge like this, how common would it be for stars to run into each other or at least pass through other solar systems??

  36. DrFlimmer

    Welcome home, Anaconda ;)

    Btw: Cygnus X-1 is a double-system. One is not detectable in optical light, the other one is. How can you explain that with a dark cloud that blocks one star (that you call to be a white dwarf) but not the other one?

  37. DrFlimmer

    @ Tom Marking:

    A galactic core (GC) is just, well, the core of a galaxy.
    An active galactic nucleus (AGN) is a core of a galaxy, too. But: Its black hole is feeding, so the core is very bright and you can probably see all of the monstrous effects of the beast, like jets, etc.
    So an AGN is a very bright GC. The Milky Way’s GC is no AGN, i.e.

  38. DrFlimmer

    @ Jdhuey:

    To your second question:
    A planet in the outskirts of the galaxies will probably survive. But it depends on some things. If the planet (or the star it belongs to) happens to sit right in the direction of the jet of one of the black holes it is definitly doomed. A very interesting picture is the one of the merging galaxy “3C 321″. Just search for it (google or BadAstronomy directly).
    If the planet is not in the range of the jets, the chances of a survival are fairly high.

  39. DrFlimmer

    @ Jojo:

    The odds of a collision are really low. The reason is that “solar systems” tend to be rather small compared to the distance between the stars (100AU (some light-hours) to several light-years).
    What you have are “gravitational encounters”. The gravity of one star distorts the movement of the other star (or the movements of objects, like planets and comets, around the other star) and vice versa.
    So the stars could come “off course” and if it has bad luck, it could be tossed into the galactic center(s), or out of the galaxy. If the stars are not disturbed on their trajectory, probably the comets at the boundary of the star’s system are. The result would be a bombardment of inner planets, just like in the early days of the solar system.

  40. José

    @DrFlimmer
    How can you explain that with a dark cloud that blocks one star (that you call to be a white dwarf) but not the other one?

    Duh. It’s a roving plasma dust ball. You can see one a good example of what these are capable of in Godzilla vs. the Smog Monster.

  41. I’m curious. When galaxies merge like this, how common would it be for stars to run into each other or at least pass through other solar systems????

  42. DrFlimmer

    Erik, are you the same guy as jojo, sincu you ask precisely the same quastion?

    No matter what, just take look at my answer above that gave to jojo….

  43. @DrFlimmer “Welcome home, Anaconda Btw: Cygnus X-1 is a double-system. One is not detectable in optical light, the other one is. How can you explain that with a dark cloud that blocks one star (that you call to be a white dwarf) but not the other one?”

    Yes, great minds think alike. That was my precise objection – how come we can easily see HDE 226868 optically? No response on that one yet.

  44. DrFlimmer

    Yes, great minds think alike.

    Oh, thanks a lot :)

  45. I just had to repost this excerpt from Anaconda. I provided a link to a formula for density:

    http://zebu.uoregon.edu/~soper/Physics/density.html

    It has the following formula:

    density = M / ((4/3) * pi * R^3)

    Anaconda says the following:

    “Please review the link. In order to calculate the density you have to know the mass and the radius, but note two things: One, the calculations are limted to planets and moons in our solar system; and, two, but not stars light-years away, specifically the Cygnus X-1 star pair, 6,000 light-years away.”

    Where is that graphic Phil has? You know, the one that says THE STUPID, IT BURNS. I can’t believe this one. This guy sounds like some junior high kid having us on. If not he’s certainly at about that mental level. :)

  46. DrFlimmer

    This is so sad if it wouldn’t be so hillarious! Oh, damn it! He’s kidding us! This is just as stupid as OiM, who’s just rejecting everything. Oh, come on…..

    So, breath easy, again.
    :D

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