Galaxy crash sparks biggest spiral

VLT/Galex image of NGC 6872 Galex revealed a wealth of new stars at the galaxy's outer reaches

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Astronomers have spotted the largest known spiral galaxy - by accident.

A team was looking through data from the Galaxy Evolution Explorer (Galex) satellite for star-forming regions around a galaxy called NGC 6872.

But they were shocked to see a vast swathe of ultraviolet light from young stars, indicating that the galaxy is actually big enough to accommodate five of our Milky Way galaxies within it.

The find was reported at the American Astronomical Society meeting in the US.

NGC 6872, a galaxy about 212 million light-years away in the constellation Pavo, was already known to be among the largest spiral galaxies.

Near it sits a lens-shaped or lenticular galaxy called IC 4970, which appears to have crashed through the spiral in recent astronomical times.

Rafael Eufrasio of the Catholic University of America and Nasa's Goddard Space Flight Center and colleagues from the University of Sao Paulo in Brazil and the European Southern Observatory in Chile were interested in a number of regions away from the galaxy.

"I was not looking for the largest spiral - it just came as a gift," Mr Eufrasio told BBC News.

Galex - a space telescope designed to search for the ultraviolet light that newly born stars put out - hinted that NGC 6872 was made much larger in size by the collision.

The team went on to use data from a range of other telescopes including the Very Large Telescope, the Two Micron All-Sky Survey and the Spitzer space telescope - each of which sees in a particular set of colours, in turn evidencing stars of varying ages.

They found the youngest stars in the outer reaches of the galaxy's enormous spiral arms, getting progressively older toward the centre.

That suggests a wave of star formation that travelled down the arms, set off by the collision with IC 4970, with the newest stellar neighbourhoods pushing the galaxy into the top spot in terms of size.

"It's been known to be among the largest for two decades, but it's much larger than we thought," explained Mr Eufrasio.

"The galaxy that collided with the [central disc of NGC 6872] splashed stars all over the place - 500,000 light-years away."

A simulation of the galactic collision suggests it happened 130 million years ago A simulation of the galactic collision suggests it happened 130 million years prior to the situation we see today

Besides being one for the record books, NGC 6872 updates the catalogue of known galaxy smash-ups, demonstrating how dramatically galaxies can be changed and added to by collisions.

"It shows the evolution of galaxies in the larger context of the Universe - how the large galaxies we had before were accreted from small clumps in the early Universe," Mr Eufrasio said.

"We're just seeing one example of two interacting galaxies but in the past that happened much more often - that's how the big [spiral galaxy] discs we have were probably formed. Putting that in a larger context, it's a very cool system."


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  • rate this

    Comment number 371.

    Please,no "God" talk.This is a page about rational thinking.It always puzzles me how people say something created the universe as it cant have always been there.But the same applies to God,yet it's never awknowledged.
    I just wish more funding would go towards space exploration.we know so little about our existance in the universe & we need a slap of reality to show just how insignificant we are.

  • rate this

    Comment number 370.

    Why are the BBC so against making Science even more accessible than it is for the children?

    Too much rubbish on TV like Eastenders, Reality TV and Kiss, Marry, Avoid.

    Let's see stuff Stargazing on every week, with the LIVE edition once a month! Let's see more stuff about the planet! Let's see science take a bigger part in the BBC's airtime.

    Educate us, don't dumb us down!!

  • rate this

    Comment number 369.

    At first you wonder "How could they have missed it all these years?". Just shows what a big place the universe is.

  • rate this

    Comment number 368.

    355.ConnorMacLeod - "......How can you be so sure ? You seem to have little confidence in the enormous potential of science & the human race...."

    I am also well informed about the basic fundamentals of physics & a realistic as to what we humans can achieve.....

  • rate this

    Comment number 367.

    As a scientist the most you can say is "I have no evidence""

    Throughout history the invocation of a supernatural being/beings was used by humans to explain the workings of the natural world. As increasingly rational explanation have been put in place for many phenomena there remains, and always will, gaps in that knowledge. Many still invoke supernatural intervention for those gaps.

  • rate this

    Comment number 366.

    Awsome, and to think that our own galaxy has maybe 17 Billion earth sized planets i wonder how many civilisations were destroyed by this event when its 4 times bigger!!!

  • rate this

    Comment number 365.

    Here's one for all of you, just think there is a planet some 13.2 billion light years away where a being is observing the creation of our galaxy.

  • rate this

    Comment number 364.

    You should direct him to the answer rather than putting him down with sarcasm.
    With respect it is not YOUR place to tell me what i should and shouldn't do.

    It is not MY place to educate RogerGod. If he chooses to raise uneducated passive/aggressive queries, that's up to him.

    My response was not sarcastic, but a quite flat rebuttal to his proposition.

  • rate this

    Comment number 363.

    @347. That's what I thought, but it's a pretty big mistake to make.

    @350. Sorry - I get the principle of red/blue shift, but not why that explains how we can see an event that took place 130 million years ago when it took place 212 million light years away.


  • rate this

    Comment number 362.

    re 352 little old me:

    the noun Politician has no requirement for the descriptive adjective dishonest to precede it

  • rate this

    Comment number 361.

    5 Minutes ago
    I'm so glad I took out Galaxy crash insurance now.
    Did you read the small print?
    "Policy not valid if taken out in the last 150 Billion years"

    Great, my Galaxy is a write off, what have I been paying this £15.00 a month for?

    On another note, I wonder if anyone has lost any of these name your own star gifts in this catastrophe? My heart goes out to those affected!

  • rate this

    Comment number 360.

    Perhaps one needs to consider what is meant by the term God. Surely we should reflect on the fact that if we can possess consciousness & intelligence within the realms of the universe, can we decree that the universe cannot possess such traits itself? We may never know the answer to the question of the existence of God as there may be higher states of self-awareness which we could never comprehend

  • rate this

    Comment number 359.

    334. Yeokel
    That's right, there is NO GOD.
    Prove it. It's hard to prove a negative, hence it's generally best to refrain from declaring them. Especially when the subject in question is a metaphysical entity capable of taking on any form to suit any argument against it's existence.

    As a scientist the most you can say is "I have no evidence."

  • rate this

    Comment number 358.

    Fabulous though this is, just think, the repulsive human race can move on to other worlds & destroy galaxies with wars, famine, land pillage, cruelty, greed and more greed. Oh and the cult of fame to go with it. That's after we've completely decimated supplies down here first. Amazing discoveries like these, for me, remain overshadowed by the sheer brutality experienced at grass roots level.

  • rate this

    Comment number 357.

    If this thing is 5 time the size of a Milky Way, then that means it would be the same size as a giant Toblerone

  • rate this

    Comment number 356.

    Its all very well being able to see these extraordinary pictures, however our understanding of science, in particular Physics, tells us that we will never visit these places due to the vast differences. we cannot achieve light speed so we will only ever be able to look and wander at these amazing sights from a distance.

  • rate this

    Comment number 355.


    "But that is just so much wishful thinking, it'll never happen"

    How can you be so sure ? You seem to have little confidence in the enormous potential of science & the human race.
    People used to say that it was impossible to fly, but it didn't stop Leonardo da Vinci thinking about it and the Wright Brothers doing it...

  • rate this

    Comment number 354.

    Sweet. My comment no.48 has -44 votes.

    Did you know there's too much salt in food. TOO MUCH SALT???? IT#S ALL THE FAULT OF THE RELIGION!!!!!!

  • rate this

    Comment number 353.

    People talk as if we are able to communicate to alien life forms well think of this. The difference in DNA between a chimp and a human is 1% and we have a sophisticated social and technological world. Now imagine if the aliens are 1% different and they are to us as we are to chimps. I do not fear for "war" with aliens, I fear that our supremacy in intelligence will be outweighed significantly

  • rate this

    Comment number 352.

    342.stu82 - "......Im pretty sure most governments would try and keep it as much of a secret as possible...."

    No chance - they'd shout it from the roof tops, all the better to rally us plebs to their cause & keep them in power as they "dealt with" the new enemy......

    ....dishonest politicans (i.e. many, but by no means all of them) love nothing more than an "other" to bring "us" together


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