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Astronomers Discover When Galaxies Got Their Spirals

Soulskill posted about 10 months ago | from the every-time-you-hear-a-bell-ring,-a-galaxy-gets-its-spirals dept.

Space 56

KentuckyFC writes "The universe today is filled with beautiful spiral galaxies — but it hasn't always been this way. In the early universe, there were no spiral galaxies, raising an interesting question: when did galaxies get their spirals, and how did they emerge? Now astronomers have the answer, thanks to an analysis of galaxies in an image taken by the Hubble Space Telescope known as the Ultra Deep Field. This shows some 10,000 galaxies of various ages. By ordering a subset of these by type and by age, astronomers have worked out how and when spirals must have evolved. It turns out the first spiral galaxies were simple two-armed structures and appeared when the universe was about 3.8 billion years old. But they say the universe had to wait until it was 8 billion years old before more complex multi-armed galaxies emerged, like the Milky Way and Andromeda."

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Evolution of complex structure. (1)

Anonymous Coward | about 10 months ago | (#45748041)

I think ~8 billion years after the Big Bang was when the Earth formed, too. Not too long after that there was life. Coincidence?

Re:Evolution of complex structure. (4, Informative)

jellomizer (103300) | about 10 months ago | (#45748101)

Well perhaps not a Coincidence.

We are a creation of a second generation star. With our heavier elements that are assumed to be a product of the first generation stars dying process.
Assuming most Stars last an average of 10 billion years. It would be save to assume the second generation started 8 billion years after the big bang. Now creating of these heavier elements probably made gravity distribution in the galaxy a little less consistent creating new shapes too.

Re:Evolution of complex structure. (4, Informative)

SJHillman (1966756) | about 10 months ago | (#45748245)

If I'm remembering my astronomy correctly, first generation stars were much larger and faster rotating, but also much shorter-lived in general - some had lifespans possibly as short as a few million years.

Re:Evolution of complex structure. (1)

east coast (590680) | about 10 months ago | (#45748405)

Can a population I star be second generation? I'm not sure of it.

Re:Evolution of complex structure. (1)

spottedkangaroo (451692) | about 10 months ago | (#45748897)

Those really big ones that produce the heavy metals don't last nearly that long. Just a ouple billion iirc.

Re:Evolution of complex structure. (2)

Opportunist (166417) | about 10 months ago | (#45749385)

I thought it was third generation? Did something new get discovered while I wasn't looking?

And as SJHillman pointed out correctly, first generation (Pop3 [wikipedia.org] ) stars were (allegedly, we still didn't see a single one of them) almost entirely H and He, insanely huge and existed for just a few million years (compared to the billions of years that contemporary stars have ... provided they ain't too big).

So I'd say we're probably orbiting one of the first stars that have enough metal to have "rock" planets and hence support life.

Re:Evolution of complex structure. (3, Informative)

Artifakt (700173) | about 10 months ago | (#45751847)

Earth formed from heavy elements produced in at least one prior generation star, but there could be more than just one prior generation (It's very, very unlikely that all or nearly all the medium weight elements above lithium, in our solar system, came from just one older star, and pretty unlikely even that all the heavies above Iron were cooked up in just one supernova).
          It's not a safe assumption that stars last an average of 10 Billion years. The most numerous types, red dwarfs, make up 80-90% of all stars, last a lot longer than that, and probably stay stable on the main sequence for 100-200 billion years (American Billions). They also shouldn't spread elements around much when they finally do leave the main sequence. Stars about the size of our Sun, spectral class G2, typically live about 10 Billion years, but make up only about 2% of stars. Big stars, type O, B, and A, burn more quickly, and it's possible to get enough hydrogen together for a star to burn through all its fuel and supernova in mere hundreds of thousands of years, or possibly even a blazing fast 10's of thousands. Those stars are rare, but they are so massive that even a few produce enough heavy elements and push enough gas around when they supernova, to create hundreds of sun sized and smaller stars and all the heavy elements to give such stars the solid, rocky planets we now think are practically ubiquitous.
            The supernova explosions are a common source for two effects - heavy element formation, and compressive shock waves that trigger new stars forming in nearby interstellar gas clouds. Many of these gas clouds are already enriched with heavy metals from previous supernovae, Spiral galaxies tend to get regions of new star formation, and quiet regions. But, the high and low density regions in spirals like our Milky Way exist on larger scales than the star forming "nursery" clouds, and this is largely because gas clouds are not just compressed by novae - both the dense star forming clouds and very large but more difuse clouds colide with other clouds, including clouds that were part of dwarf galaxies being captured by the big spirals. So, it's a partial coincidence - Older generation stars have some influence on the shapes of spiral galaxy features, but dwarf galaxy capture has more, and the rare colisions of spirals with other big galaxies show just how much influence the large scale objects can have, producing wildly twisted galaxys such as

          If anyone wants to read up on this sort of thing, please remember, because astronomers named them before they knew anything about why there were multiple distinct types of stars in the same mass ranges, Population II stars are actually older than Population I, and Population III older than II. A given population usually includes multiple generations of stars. As an exception, the very oldest, massive stars that novaed within the first million years or so after star formation began, and produced so many heavy elements are called Population III, and most probably represent just a single generation and possibly only the largest types.

https://en.wikipedia.org/wiki/Stellar_nursery#Stellar_nurseries [wikipedia.org]

https://en.wikipedia.org/wiki/Galactic_collision [wikipedia.org]

https://en.wikipedia.org/wiki/Population_I_stars#Population_I_stars [wikipedia.org]

and, for those people wanting more than just the Wikipedia versions, a little real source material:

http://arxiv.org/pdf/astro-ph/0012399v2.pdf [arxiv.org]

   

Re:Evolution of complex structure. (1)

TheCarp (96830) | about 10 months ago | (#45748121)

There are no coincidences:
"I find the Law of Fives to be more and more manifest the harder I look."
- Omar Khayyam Ravenhurst

Re:Evolution of complex structure. (0)

Anonymous Coward | about 10 months ago | (#45748751)

"I'm so horny!" --The winking unicorn, Illuminatus Trilogy

Re:Evolution of complex structure. (1)

NatasRevol (731260) | about 10 months ago | (#45748755)

Holy random comment, batfish!

Re:Evolution of complex structure. (1)

TheCarp (96830) | about 10 months ago | (#45749589)

Its only random if you aren't finding coincidences everywhere :)

Re:Evolution of complex structure. (1)

lgw (121541) | about 10 months ago | (#45749783)

The comment was perfectly on-topic if you understood it. It summarizes the main theme of a trilogy of books: the human mind is better at spotting patterns than the universe is at creating them. So if something seems like an unlikely coincidence, the best assumption is that it is an unlikely coincidence, unless you can hypothesize a reasonable mechanism to explain the connection (and then make successful predictions using that).

Re:Evolution of complex structure. (1)

TheCarp (96830) | about 10 months ago | (#45766509)

I am glad somebody got it.

It is amusing to consider it a summary since it is a direct quote from the source material that the book was referencing :) Means the same either way of course.

Re:Evolution of complex structure. (1)

MRe_nl (306212) | about 10 months ago | (#45749195)

"I find the Law of Eight Billion to be more and more manifest the harder I look."
- Papa Smurf

Re:Evolution of complex structure. (1)

davester666 (731373) | about 10 months ago | (#45752477)

Jesus was bored, flicked a couple of galaxies with his finger and thought it looked cool, so he did it to them all. He started making them look crazier and crazier until God told him to cut it out, or else.

And everybody knows, you NEVER go "or else what" to him...

Thank you for not begging the question (-1, Offtopic)

Spy Handler (822350) | about 10 months ago | (#45748043)

KentuckyFC.

Kamina would be proud (0)

Anonymous Coward | about 10 months ago | (#45748065)

n/t

Meh (2, Funny)

bob_super (3391281) | about 10 months ago | (#45748175)

The answer is obvious to anyone who likes old-style mythology:

When the gods rotate the universe to look for their next vacation spot, the resulting Coriolis force makes galaxies spin. They don't all spin in the same direction because of The Great Nebula Outing Debate of 10 000 000 000 PBB (Post-Big-Bang), when the Almighty-Mothers-In-Law kept rotating back and forth until The-So-Cute-One (then a toddler at barely 10000 years old) randomly sneezed a few more stars on Orion.
Ever since that event, people on Durandil Major have been unable to predict the way the water will flow when they flush their toilets.

Re:Meh (0)

Anonymous Coward | about 10 months ago | (#45748321)

Although, with only 2 possibilities, the Durandilians have nearly a 50% chance of guessing correctly. Up, or Down.

Re:Meh (1)

QilessQi (2044624) | about 10 months ago | (#45748529)

Your ideas are intriguing to me and I wish to subscribe to your religion.

Re:Meh (1)

Bucc5062 (856482) | about 10 months ago | (#45749617)

May you consider this one [wikia.com] as an alternate?

Re:Meh (1)

Anonymous Coward | about 10 months ago | (#45748843)

Except all galaxies DO spin the same direction [cornell.edu] .

Re:Meh (1)

scuzzlebutt (517123) | about 10 months ago | (#45749431)

Nice try.

Interesting trend... (1)

morbis (1130705) | about 10 months ago | (#45748185)

If it took an additional 4.2 billion years for multiple arms to emerge, what will these galaxies morph into in another 4.2 billion years?

Re:Interesting trend... (3, Funny)

SJHillman (1966756) | about 10 months ago | (#45748263)

If Japan is any indication, multiple tentacles are usually followed by bukkake.

Seems like a small sample (4, Interesting)

tomhath (637240) | about 10 months ago | (#45748273)

The Elmegreens examined 269 spirals in the Hubble Ultra Deep Field and discarded all but 41 because of factors such as an inability to discern a clear spiral structure or the lack of redshift data which gives a galaxy’s age.

They divided these 41 spiral galaxies into five different types, based on features such as the number and clarity of arms, whether well-defined or clumpy and so on.

It sounds like they only found a few of each type, seems more like a good hypothesis than "the answer". It also makes you wonder if they cherry picked some of their data.

Re:Seems like a small sample (0)

Orne (144925) | about 10 months ago | (#45748373)

That never happens, this is Science we're talking about here!

Re:Seems like a small sample (5, Insightful)

DRJlaw (946416) | about 10 months ago | (#45748861)

The Elmegreens examined 269 spirals in the Hubble Ultra Deep Field and discarded all but 41 because of factors such as an inability to discern a clear spiral structure or the lack of redshift data which gives a galaxyâ(TM)s age.

They divided these 41 spiral galaxies into five different types, based on features such as the number and clarity of arms, whether well-defined or clumpy and so on.

It sounds like they only found a few of each type, seems more like a good hypothesis than "the answer". It also makes you wonder if they cherry picked some of their data.

Imagine that you're attempting to determine when spiral structure typically arose.

1. You throw out all non-spirals: not relevant.
2. You throw out proto-spirals where there's mushy arm-sh structures: potential bias, yes but
2a. You also throw out other spirals where you cannot objectively classify them as grand (2) or multi-armed (>2) spirals or... to one of the five types -- not an inherent time bias.
3. You throw out all data where you have no redshift to determine age: potential bias, yes but
3a You're attempting to determine a relationship with age. If you have no age data, how is that cherry picking?

There is a difference between objectively screening data based on logical considerations and cherry picking. Cherry picking typically involves biased selections or the use of supposedly objective selection criteria to obtain a directed result. I say supposedly because the true objectivity depends upon how the selection criteria actually relate to the hypothesis or analytical method.

As for the rest, I don't see how the paper claims to have "the answer." You're also incorrect that it's a good hypothesis -- the hypothesis is what you test against the data, not the conclusion that your observations are consistent with the hypothesis. They have a decent conclusion of consistency. Now they could use independent confimation, hopefully with a larger population of samples.

Nice try (0)

Anonymous Coward | about 10 months ago | (#45748279)

By ordering a subset of these by type and by age, astronomers have worked out how and when spirals must have evolved.

Who exactly figured this out and how reliable is that equation? That is one hell of a smart person in my book.

So did we help with this report? (3, Interesting)

malakai (136531) | about 10 months ago | (#45748303)

I recall a few years ago participating with a lot of others in a crowd source effort to categorize fuzzy pictures of possible galaxies. I think it was galaxy zoo.

So is this the result of our effort? Would be nice to know...

Re:So did we help with this report? (1)

Kiwikwi (2734467) | about 10 months ago | (#45752985)

So is this the result of our effort?

Don't know, but scuzzlebutt posted an interesting link [cornell.edu] further up, at which you can read:

Scientists believe that on large scales the Universe is isotropic (the same in all directions). Thus, from our perspective, half of all spiral galaxies should spin clockwise, and half counter-clockwise. A recent analysis of the spin of spiral galaxies confirms this. The public classified over 35,000 spiral galaxies with spins both clockwise and counter-clockwise in the Sloan Digital Sky Survey as part of the Galaxy Zoo project.

Our time has not been wasted. :)

Bait and Switch Summary (2, Insightful)

Anonymous Coward | about 10 months ago | (#45748323)

The summary says they have figured out how and when the spirals formed.
But the linked articles only say when, not how.

May the summary writer burn in hell for all eternity.

Forming accretion disks (2)

Framboise (521772) | about 10 months ago | (#45748341)

Retrospectively it could have been guessed long ago that disk galaxies need at least a few tens of rotation periods to look progressively like symmetric accretion disks in other astrophysical contexts (disks around black-holes, stars or planets). The difference between galaxies and smaller disks is mainly the number of rotations they could make, a few tens of rotations for spiral galaxies, millions or billions for smaller disks.

Re:Forming accretion disks (5, Interesting)

PPH (736903) | about 10 months ago | (#45748653)

This.

The mathematics governing many physical phenomena is strikingly similar. Its the frequency and wavelength that make them look radically different. Heat dissipation due to day/night cycles through a structure looks a lot like microwave attenuation in a surface. Same math, different time scale.

It also makes one wonder if the eventual form of a galaxy will resemble a planetary disc, with a bunch of large bodies (black holes?) orbiting a really big central one, surrounded by largely empty space.

Re:Forming accretion disks (1)

blue trane (110704) | about 10 months ago | (#45751133)

Except the math of planetary orbital speeds doesn't work for the orbital speeds of stars in galaxies.

Re:Forming accretion disks (1)

similar_name (1164087) | about 10 months ago | (#45751691)

Could you expand on that? What are the two maths? Isn't a fundamental premise of physics that the laws behave the same everywhere in the Universe.

Re:Forming accretion disks (1)

blue trane (110704) | about 10 months ago | (#45751751)

Predictions of rotation speed of stars towards the edges of galaxies do not agree with Keplerian predictions used to predict the orbital speed of planets around our sun. So either gravity doesn't behave the same in the outer parts of galaxies as it behaves around our sun, or (the hypothesis) there is some other mass that we can't see (dark mass). Right now, what we know is that observations don't match predictions based on the math that works for our solar system's planets.

http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit6/dark.html [ohio-state.edu]

Re:Forming accretion disks (1)

similar_name (1164087) | about 10 months ago | (#45751817)

Thanks, that helped me understand support for dark matter as well. For clarification though, would it be fair to say that we do use the same math and when the answer didn't fit our prediction, we didn't change the math, but rather assumed the math is right and that we must not be able to observe all of the mass?

Re:Forming accretion disks (1)

blue trane (110704) | about 10 months ago | (#45751869)

Yes, that is the working hypothesis.

But at the bottom of the web page I linked, it says:

Maybe Dark Matter and Dark Energy don't exist at all!
Is our theory of gravity wrong on large scales?

So that's also a hypothesis (though not currently popular).

Re:Forming accretion disks (1)

rusty0101 (565565) | about 10 months ago | (#45752621)

Also not necessarily consistent with the observation of the effects of gravity on light passing by clusters of galaxies, and the fact that galaxies appear to be accelerating away the further the galaxy appears to be.

This does not mean that our theory of gravity isn't wrong on large scales, and perhaps dark matter and dark energy do not have the level of influence that our current theory projects, but we are seeing effects that essentially suggest that there is something like anti-gravity working across very long distances.

Re:Forming accretion disks (1)

PPH (736903) | about 10 months ago | (#45755679)

Think about the 'closed model' of the universe. The one that says space-time is closed on itself like the surface of a balloon and if you shot a beam of light into space, eventually it would loop around and hit you in the ass (sorry for the overly technical terminology).

Gravity would work around this curve as well. The force that would decelerate two galaxies moving apart would be counteracted by a (much smaller) force of the two galaxies attracting each other around the longer route of the closed curve.

Re:Forming accretion disks (1)

Bengie (1121981) | about 10 months ago | (#45751789)

Dark matter creates issues by messing with mass distribution.

Re:Forming accretion disks (0)

Anonymous Coward | about 10 months ago | (#45753057)

Here is the "Odd" question, one that they would not awnser back when I was star-looking at her feet. She kept saying up-here. But...how do you suppose about dark matter? Meaning, if there is a dark matter, It should have one of two states, either smooth, which supposes a broth, or clumpy, as in like chicken noodle soup, clumps of matter. This may be observed, By the "affects/effects" of the outer orbits of the systems, yes many year, time effect. I know its only a hundred years, but has the effect been seen yet?
Dark matter presupposes that is not seen, but guesstimated because the math don't work. But like climate science, could it be because you were looking at the wrong area? Or applying annologies that do not recreate the condition observed?

Re:Forming accretion disks (1)

PPH (736903) | about 10 months ago | (#45755611)

Probably because gravity (the gravitational constant) will turn out not to be scale invariant.

Dark matter/dark energy might work as explainers for expansion of the universe and rotational velocities of parts of galaxies. But once that theory is accepted, one will have to explain why dark whatever doesn't seem to affect planetary motions and someone dropping cannon balls off a tower.

Re:Forming accretion disks (0)

Anonymous Coward | about 10 months ago | (#45750813)

Frame drag from a spinning central black hole comes to mind. The spinning speed would then determine the structure of the galaxy.

I know when.... (2)

Lumpy (12016) | about 10 months ago | (#45748421)

The guy that picked up the snowglobe and gave it a twist... Sadly that is when the great galactic disaster happened and most of the residents of Betelgeuse IV died.

dizzy.. (1)

Black Parrot (19622) | about 10 months ago | (#45748851)

Those deep field photos always give me vertigo.

The arms are poles of an electrical charged fields (0)

Anonymous Coward | about 10 months ago | (#45749389)

ever notice it's always an even number of arms???
An Electric universe / Sun theorizes that we are all electrically joined... all the parts.
  Even across the vastness it's dark energy/matter that's joining us together with fields.
As an electrical worker and study nut, I see it in nature everywhere even the weather.
So why wouldn't the arms of the galaxies be poles of the huge generators / magnetos
that the galaxies are? Riding the force be it 'dark' or 'light.' amazing thoughts to consider.

Re:The arms are poles of an electrical charged fie (0)

Anonymous Coward | about 10 months ago | (#45749957)

ever notice it's always an even number of arms??? An Electric universe / Sun theorizes that we are all electrically joined... all the parts.

Sounds to me like you are positing a falsifiable hypothesis. Bravo! Quite the rarity amongst ACs on Slashdot. So if we can find one odd-numbered spiral galaxy, the electric universe hypothesis is disproved? I wonder if we could do that?

Re:The arms are poles of an electrical charged fie (1)

blue trane (110704) | about 10 months ago | (#45750401)

This is the only post so far that mentions dark matter. Without dark matter, the galaxy spirals should be much less rigid. Did the old galaxies with two arms also reveal the presence of dark matter, so that its presence has been constant throughout the age of the universe? Or do they just ignore dark matter and treat it as a given that stars at the edge of galaxies orbit at the same speed as stars closer in, unlike our solar system with its gravity constraints?

Photoshop filter? (0)

Anonymous Coward | about 10 months ago | (#45749563)

When they had to obscure their participation in kiddie porn?

Could it be ... (0)

Anonymous Coward | about 10 months ago | (#45750081)

When Stella got her groove back?

proves evolution wrong (0)

Anonymous Coward | about 10 months ago | (#45751069)

Spiral galaxies prove the universe is not billions of years old. Otherwise the spirals would have spun out by now. There shouldn't be spiral arms after bilions of years. The universe was created 6 thousand years ago by the God of the Bible. Watch kent hovinds videos for information this and how it is scientifically impossible for the universe to be billions of years old.

Great D'sarcasmus (0)

Anonymous Coward | about 10 months ago | (#45751635)

Yes - you are absolutelly right. God only created mere ~5000 stars and they are hardly enough to make any spirals. But if we suppose, that God put spirals recently, then it makes sense, that he also burried on Earth some bones of dinos, otherwise they would be present on raft of Noa.

So what is the explanation? (1)

mc68386 (746055) | about 10 months ago | (#45751927)

From looking at TFA what I garner is that galaxies got arms a long time ago "as they got older". Specifically: "Then the clumps elsewhere in the glalxy (sic) begin to smear out forming woolly, indistinct arms." Nailing down the process, they follow with "More complex structures follow later." Wow, mystery solved. Now I seem to remember some research 10 or so years ago that showed through computer simulations that 2 galaxies composed of homogeneous distributions of stars, if they pass relatively close to each other at speed, will affect each other and cause each one to form spiral arms. That made intuitive sense, backed up with data. This article... really... what does this article say?
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