Hubble catches the moment the lights went out

Feb 06, 2013

(Phys.org)—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. (although not the Milky Way) are often large, 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 within them. A merger will usually be a trigger for such 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 , 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.

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User comments : 5

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rubberman
4.6 / 5 (15) Feb 06, 2013
I'd personally like to thank our galaxy for being around long enough and fusing enough hydrogen into heavier elements to make the pondering of it's existence by our race possible. The more we learn, the older it seems we are in relation to the rest of what we see, save for the galaxies in our immediate neighbourhood.
antialias_physorg
4.6 / 5 (11) Feb 06, 2013
Well, it probably would be more 'exciting' in galaxies that were around earlier.
Then again: stars bursting into life at a rapid rate in one's vicinity might not be conductive to an environment stable enough to allow life to develop.
BSD
4 / 5 (4) Feb 07, 2013
I'm constantly amazed by what NASA have achieved with Hubble, all for the relatively small sum of $2.5 Billion. Pity the Government has seen fit not to maintain it any more. Compared to the cost of waging wars that end in stale mate, Hubble is bargain.
yyz
5 / 5 (2) Feb 07, 2013
"Pity the Government has seen fit not to maintain it any more."

Actually, NASA has plans to use Hubble and the JWST for overlapping observations when the latter launches in 2018: http://news.yahoo...702.html

So no forced retirement. And Hubble is a bargain. The above article notes that the 2013 budget for JWST is $628 million vs $98 million for Hubble.
GSwift7
5 / 5 (2) Feb 12, 2013
Then again: stars bursting into life at a rapid rate in one's vicinity might not be conductive to an environment stable enough to allow life to develop.


That's exactly what I was thinking when I read the phrase "red and dead". Maybe in terms of star formation and such, but just as you say, that's probably a good thing for anyone actually living there. I wouldn't be surprised if these "red and dead" galaxies are the intergalactic hubs of interplanetary civilations. In fact, I'd be willing to bet on it, if there was ever a way to conclude the bet. lol.

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