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Hubble Catches the Moment the Lights Went Out

galaxies eliptical galaxies galactic mergers star formation hubble red and dead

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#1    Waspie_Dwarf


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Posted 02 February 2013 - 11:46 PM

Hubble Catches the Moment the Lights Went Out

www.nasa.gov said:

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The further away you look, the further back in time you see. Astronomers use this fact to study the evolution of the Universe by looking at nearby and more distant galaxies and comparing their features. Hubble is particularly well suited for this type of work because of its extremely high resolution and its position above the blurring effects of the earth's atmosphere. This has allowed it to detect many of the most distant galaxies known, as well as making detailed images of faraway objects.

Comparing galaxies in the distant past with those around us today, astronomers have noticed that the nearby galaxies are far quieter and calmer than their distant brethren, seen earlier in their lives. Nearby galaxies (although not the Milky Way) are often large, elliptical galaxies with little or no ongoing star formation, and their stars tend to be elderly and red in color. These galaxies, in astronomers' language, are "red and dead."

This is not so for galaxies further away, which typically show more vigorous star birth.

The reason for this appears to be that as the Universe has aged, galaxies have often collided and merged together, and these events disrupt gas clouds within them. A merger will usually be a trigger for such intense star formation that the supply of gas is used up, and no more star formation occurs afterwards. The merged elliptical galaxy then creeps into old age, getting redder as its stars get older. This is expected to happen to the Milky Way when it merges with the nearby Andromeda Galaxy, some four billion years from now.

The galaxy in this image, catalogued as 2MASX J09442693+0429569, marks a transitional phase in this process as young, star-forming galaxies settle to become massive, red and dead galaxies.

The galaxy has tail-like features extending from it, typical of a galaxy that has recently undergone a merger. Studying the properties of the light from this galaxy, astronomers see no sign of ongoing star formation; in other words, the merger triggered an event which has used up all the gas. However, the observations suggest that star formation was strong until the very recent past, and has ceased only within the last billion years. This image therefore shows a snapshot of the moment star formation stopped forever in a galaxy.

A version of this image was entered into the Hidden Treasures image processing competition by contestant Nick Rose.  

ESA/Hubble & NASA

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Edited by Waspie_Dwarf, 30 May 2014 - 05:48 PM.
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"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#2    Overpopulation


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Posted 03 February 2013 - 12:15 AM

Wow pretty stunning. I doubt we will ever see something like this again. I <3 Hubble

#3    pitchp


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Posted 03 February 2013 - 02:34 AM

This universe is set for destruction. Unlike this universe, we don't die for some reason, we simply evolve from lifetime to lifetime. Everything is just an illusion, and we are all caught up in it, one way or another.

"The truth is out there. We are all searching for it."

#4    coolguy



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Posted 03 February 2013 - 05:59 AM

Very awesome picture thanks for posting

#5    Frank Merton

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Posted 03 February 2013 - 06:14 AM

I like the point that as we see out into space we also see backward in time, with several consequences.

First, we never see the universe as it is right now, but always as it was at some point in the past -- the further away, the further back in the past.

Second, this allows us to see how galaxies evolve, since we get a picture of what they were like early on.  The fact that quasars were much more numerous in the past than they are more recently is an example.

Third, we can measure the rate at which the universe has been expanding at different times in the past, and so have been able to determine that the expansion rate slowed down under gravity for awhile, but as objects became further and further apart the force of gravity became weaker and at a given point some unknown force that we call "negative energy" became more powerful and since then the rate of expansion of the universe has been increasing.

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