Is The Milky Way Doomed By Galactic Bombardment?

Article written: 31 Aug , 2009
Updated: 24 Dec , 2015
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As scientists attempt to learn more about how galaxies evolve, an open question has been whether collisions with our dwarf galactic neighbors will one day tear apart the disk of the Milky Way.

That grisly fate is unlikely, a new study now suggests.

While astronomers know that such collisions have probably occurred in the past, the new computer simulations show that instead of destroying a galaxy, these collisions “puff up” a galactic disk, particularly around the edges, and produce structures called stellar rings.

The finding solves two mysteries: the likely fate of the Milky Way at the hands of its satellite galaxies — the most massive of which are the Large and Small Magellanic Clouds — and the origin of its puffy edges, which astronomers have seen elsewhere in the universe and dubbed “flares.”

The mysterious dark matter that makes up most of the universe plays a role, the study found.

Astronomers believe that all galaxies are embedded within massive and extended halos of dark matter, and that most large galaxies lie at the intersections of filaments of dark matter, which form a kind of gigantic web in our universe. Smaller satellite galaxies flow along strands of the web, and get pulled into orbit around large galaxies such as our Milky Way.

Ohio State University astronomer Stelios Kazantzidis and his colleagues performed detailed computer simulations of galaxy formation to determine what would happen if a satellite galaxy — such as the Large Magellanic Cloud and its associated dark matter — collided with a spiral galaxy such as our own.

The researchers considered the impacts of many different smaller galaxies onto a larger, primary disk galaxy. They calculated the likely number of satellites and the orbital paths of those satellites, and then simulated what would happen during collision, including when the dark matter interacted gravitationally with the disk of the spiral galaxy.

The conclusion?  None of the disk galaxies were torn apart.  To the contrary, the primary galaxies gradually disintegrated the in-falling satellites, whose material ultimately became part of the larger galaxy.  The satellites passed through the galactic disk over and over, and on each pass, they would lose some of their mass, a process that would eventually destroy them completely.

Though the primary galaxy survived, it did form flared edges which closely resembled our galaxy’s flared appearance today.

Does that settle the question of the fate of the Milky Way?

Kazantzidis couldn’t offer a 100-percent guarantee.

“We can’t know for sure what’s going to happen to the Milky Way, but we can say that our findings apply to a broad class of galaxies similar to our own,” Kazantzidis said. “Our simulations showed that the satellite galaxy impacts don’t destroy spiral galaxies — they actually drive their evolution, by producing this flared shape and creating stellar rings — spectacular rings of stars that we’ve seen in many spiral galaxies in the universe.”

Source: Ohio State University


16 Responses

  1. ILOVETHESTAR says

    These ‘midget galaxies’ are just food for the ‘big fish’ , the Milky Way Galaxy. A ‘rumble’ with another ‘ big fish’, the Andromeda Galaxy is another story, and fortunately for humans,
    these ‘no-hold barred fights of the titans’ can be viewed from a safe distance

  2. IVAN3MAN says

    Astronomers believe that all galaxies are…

    I wish that science writers would avoid using the term “believe” when referring to the thoughts of astronomers and scientists in general, and instead use the proper term “hypothesize”. We science-minded types have enough trouble from frigging creationists who think that evolution and the Big Bang are “beliefs” and “a religion”. 🙄

  3. Astrofiend says

    “I wish that science writers would avoid using the term “believe” when referring to the thoughts of astronomers and scientists in general, and instead use the proper term “hypothesize”.”

    Yeah – but it’s such a pain in the arse to write! 🙂

  4. Dave Finton says

    It will be a different story altogether if/when Andromeda ever gets here.

  5. Lawrence B. Crowell says

    Andromeda and Milky Way are expected to dance the tango starting about 2 billion years from now. The two spiral galaxies will be gravitationally distended and eventually merge into an elliptical type of galaxy.

    Earth will have become a Venus-like planet around this time, and of course humanity will be sleeping the eternal sleep of extinction. Too bad we can’t build a giant Bussard ramject and head out to ultra-relativistic velocities. The crew on board could see a lot of the future of the universe unfold before them.

    LC

  6. ILOVETHESTAR says

    Dave Finton Says
    ‘It will be a different story altogether if/when Andromeda ever gets here’
    Lol-I’m a lazy writer, I should’ve said -…,the Andromeda Galaxy is a different situation……
    AND …… titans colliting galaxies can be viewed from a safe distance now with large telescopes

  7. Nexus says

    @Lawrence B. Crowell
    “of course humanity will be sleeping the eternal sleep of extinction”

    I think that if we manage to avoid not extinguishing our species in the next hundred years, we’ll eventually colonize the galaxy and survive the death of our Solar System. And, of course, if our Galaxy and Andromeda collide it will be a very good thing for us because wherever you have clouds of gas colliding you get star formation, which means plenty of new planets for our distant descendants to play with.

  8. Torbjorn Larsson OM says

    Dark matter rulez. [Well, technically dark energy rulez. But globally.]

    Good to see another test of DM, and one which explains galaxy features. Here is pictures of disks flaring.

    Though “stellar rings” seems to be ambiguous terminology, or rather I get a defunct definition when googling. Wonder how they look like?

    means plenty of new planets for our distant descendants

    Yes. I seem to remember someone claiming that the Milky Way/Andromeda merger is one of the last expected in the observable universe. If that’s true it is lucky indeed.

  9. Lawrence B. Crowell says

    I doubt that humanity will star travel. We might send probes to nearby stars, but I space is basically lethal, lightyear distances enormous and the time-energy scales required to send humans to other stars daunting.

    We might be lucky to survive the 21st century, let along billions of years hence.

    LC

  10. HeadAroundU says

    LC, you are limited like a horse with blinkers. We don’t have to travel developed. We can send just genetic material. Also, isn’t there some kind of magnetic shield being developed!?

  11. Lawrence B. Crowell says

    We could have sent human DNA on the Voyagers. But what then? You have to run that genetic information within some context. The genetic code is in the hierarchy of formal languages, or Chomsky scheme, similar to a context sensitive language. Genetic information on a spacecraft around a planet such as Jupiter or Venus is not going to be “parsed” into anything.

    The power of the human mind lies in our ability to abstract and solve. I think our powers to colonize or control the natural world appears limited.

    LC

  12. HeadAroundU says

    Sperm + egg cell + artificial womb. 300 earth-like planets that Kepler will find. Supercomputer that will raise the kids. No imagination at all!!!??? In million years we will make a god from a shit that will create another universe. 😀

  13. Nexus says

    I still think Lawrence Crowell is being too pessimistic. Sending colony ships to other solar systems may be difficult, dangerous, and scandalously expensive- but the alternative is to do nothing and eventually face death by red giant. I know which option I prefer.

  14. Lawrence B. Crowell says

    The problems which face human survival have a time frame of a century or so into the future. Billions of years from now are beyond consideration. Our problems stem from the fact we are some sort of terminator species which is doing an extraordinary job of tearing down the planetary biosphere.

    The average mammalian species exists for a couple of millions of years. Our hominid relatives and ancestors faired no better, and in many ways worse. Neanderthals existed only 350k-years. We have only been around 100-150k-years. Species longevity is the province of the simpler life forms, particularly bacteria. Insects are by comparison very complex life forms, but simple enough to have lasted 350 million years.

    Our power, if we want to call it that, is that for some time in the universe there came sufficient organizational complexity so that subunits of the universe observed and thought about itself.

    Lawrence B. Crowell

  15. Jon Hanford says

    It looks like there may be more than just the Milky Way-Andromeda Galaxy collision to look forward to. Over the past few years, researchers have been looking at the possibility of a past encounter between the Andromeda Galaxy and M 33 and a possible future merger. A new paper and movie that illustrates the orbital dynamics between M 31 and M 33 can be found here: http://arxiv.org/abs/0909.0398 . M33 is, of course, the third largest galaxy in the Local Group.

  16. Jon Hanford says

    A 2008 paper outlined a detailed study of an ‘HI bridge’ between M 31 and M 33. An e-print of the paper here: http://arxiv.org/abs/0807.1161 . Add to this the gradual infall of the Local Group into the Virgo Cluster, the distant future look of our local universe will appear quite different.

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