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Disc galaxies formed much later than expected

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posted on Oct, 19 2012 @ 03:18 PM
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It seems that Disc galaxies formed much later than expected, says NASA astronomers. It seems that most of the galaxies were formed out of chaotic not structured spiral galaxies as we see today . But formed just after 8 billion years ago, assumed that they did that after 5 billion years ago.



NASA | Computer Model Shows a Disk Galaxy's Life History. Simulations such as this will help astronomers better understand the new findings in galaxy evolution. It tracks the development of a single disk galaxy from shortly after the Big Bang to the present day. Colors reveal old stars (red), young stars (white and bright blue) and the distribution of gas density (pale blue); the view is 300,000 light-years across.





Then maybe our galaxy dating will maybe soon be adjusted? And if I think further on that ,then maybe our solar system who is formed with the our milky way is much older then previously thought?


Many astronomers have long assumed that by an age of about 5 billion years, disk galaxies had come to look nearly the same as they appear today. “It’s almost like a mantra,” Kassin said. “Many astronomers say that the Hubble sequence is in place by a redshift (which astronomers denote with the letter z) of 1,” using astronomical shorthand for two important concepts. The Hubble sequence is a diagram—originally devised by Edwin Hubble in 1926—for classifying the visible shapes of galaxies. Because looking far out into the depths of space is the equivalent of looking back in time to earlier eras in the universe, the redshift z is how astronomers measure both age and distance in the universe; a redshift of z = 1 corresponds to approximately 8 billion years ago, when the universe was only about 5 billion years old.



Nasa


edit on 19-10-2012 by 0bserver1 because: (no reason given)




posted on Oct, 19 2012 @ 04:28 PM
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Boring... I know I never had to choose this topic pfff



posted on Oct, 19 2012 @ 07:32 PM
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My god it is beautiful. We talk about galaxies forming and colliding but we never talk about how violent the process is. We have a hard time comprehending what galactic formation looks like on its own time scale.

Thank you so much for sharing


Try posting this thread again after the election. Politics seems to be consuming the attention of ATS lately.
edit on 19-10-2012 by Mkoll because: (no reason given)



posted on Oct, 19 2012 @ 07:45 PM
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This is very interesting indeed. I've always wondered what affect gravitational lensing is having on our view of very old and far away objects. We can't assume that we have a clear view with nothing in between us and the far away galaxy. And the further away a galaxy is, increases the likelihood that a heavy mass object or many objects may be in the line of sight, causing gravitational lensing, which distorts the image and changes the apparent redshift. Are distant galaxies really as far away as they seem by their redshift or is gravitational lensing making them seem farther (and thus older) then they really are? Are early galaxies really so disorganized or are their images being smeared and distorted by gravitational lensing?

Here is a quote from the ASU School of Earth and Space Exploration:




A very massive object – or collection of objects – distorts the view of faint objects beyond it so much that the distant images are smeared into multiple arc-shaped images around the foreground object. According to Rogier Windhorst, one of the letter’s authors and a professor at the School of Earth and Space Exploration in Arizona State University’s College of Liberal Arts and Sciences, this effect is analogous to looking through a glass coke bottle at a light on a balcony and noticing how it is distorted as it passes through the bottle. Cosmologists such as Windhorst believe that gravitational lensing likely distorted the measurements of the flux and number density of the most distant galaxies seen in the recent deep near-IR surveys with the Hubble Space Telescope Wide Field Camera 3.

When you look back to when the universe was young, you are seeing extremely early objects (also known as ``First Light’’ objects) that are very far away. The older and farther away the object, the more foreground universe there is to look through, which means the greater the chance that there will be something heavy in the foreground to distort the background image. This research suggests that gravitational lensing is likely to dominate the observed properties of very early galaxies, those that are at most 650-480 million years old (now seen with Hubble at redshifts of z > 8-10, respectively). The halos of foreground galaxies when the universe was in its heydays of star formation (about 3-6 billion years old and at a lower redshift of z=1-2) will gravitationally distort most of these very early objects.


Cosmic magnifying lenses distort view of distant galaxies

I don't think we fully appreciate that when we look at the night sky, what we are actually viewing is a froth of gravitational lens bubbles which are magnifying, distorting, dimming, brightening, and smearing nearly every viewable object. Imagine a photograph of stars in a shallow pool of water overlayed with a layer of soap bubbles. Roughly, that is what gravitational lensing is doing, but we are unaware of the bubbles.

If a perfect spiral galaxy existed 13 billion light years away, would it look like an organized spiral galaxy or would it look chaotic and distorted, the way galaxies at that distance always seem to look?


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posted on Oct, 19 2012 @ 08:59 PM
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They keep refining the resolution of missions to measure relative star motions.

The Hipparcos mission measured 118,000 stars to a resolution of 0.6-1.0 milliarc-sec.
The GAIA mission next year plans to determine the proper motion of 1 billion stars with an accuracy of about 20 µas (microarcsecond).

en.wikipedia.org...

I know this is a stupid question but whats new since Eddingtons 1919 polar expedition was being debated?
Is there something fundamental that will be proved/disproved with the higher resolution?

The long term timing of certain astronomical events could be refined but how is this important except maybe to settle a wager?



posted on Oct, 20 2012 @ 05:14 PM
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reply to post by Mkoll
 





Try posting this thread again after the election. Politics seems to be consuming the attention of ATS lately.


I know your right. Its almost November 6th but I think there will only be more budget cuts in space exploration.





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