Elliptical galaxies much younger than previously thought?
The galaxy NGC 5557 clearly exhibits extremely extended and faint tidal streams spanning more than 1.2 million light-years from left to right on this image from the MegaCam mounted on the Canada-France-Hawaii Telescope. Image by P.-A. Duc 2011 (c) CEA/CFHT
(PhysOrg.com) -- The standard model for elliptical galaxies formation is challenged by a new result uncovered by an international team of astronomers from the Atlas3D collaboration. Team members from CNRS, CEA, CFHT, and the Observatoire de Lyon published in the scientific journal Monthly Notices of the Royal Astronomical Society the first results from their study on two elliptical galaxies exhibiting features characteristic of a fairly recent merging, suggesting they are five times younger than commonly thought.
The common belief on the mass assembly history of massive elliptical galaxies based on their stellar population leads to an age between 7 and 10 billion years old. A different story is shaping up based on ultra-deep images of two galaxies observed with the MegaCam camera mounted on the Canada-France-Hawaii Telescope (CFHT, CNRC/CNRS/University of Hawaii).
Astronomers from CNRS, CEA, CFHT, and the Observatoire de Lyon, all members of the Atlas3D international collaboration, established that the formation of the two studied elliptical galaxies (NGC 680 & NGC 5557) originated from a merger of two giant spiral galaxies that took place only 1 to 3 billions years ago. Such age estimate is based on the presence of ultra faint filaments in the distant outskirts of the galaxies. These features called tidal streams in the astronomers parlance are typical residuals from a galaxy merger. They are known not to survive in this shape and brightness for more than a few billion years, hence the new age estimate of the resulting elliptical galaxies. These structures were detected for the first time thanks to a very-deep imaging technique boosting the capabilities of CFHT's wide-field optical imager MegaCam.
A sample of elliptical galaxies from the Atlas3D survey current collection, all showing clear signs of a recent collision. Image by P.-A. Duc 2011 (c) CEA/CFHT
The Atlas3D team conducts a systematic survey of more than one hundred nearby elliptical galaxies. If the current result based on the first two galaxies is confirmed on the larger sample, i.e. faint extended features are frequently detected, the standard model for elliptical galaxies formation should be revisited.More information: http://lanl.arxiv. … df/1105.5654
Provided by Canada-France-Hawaii Telescope
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Jul 21, 2011
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Jul 21, 2011
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Most likely by looking at their pet models which the mainstream "ignores" and even "conspires against."
Jul 21, 2011
Rank: 1 / 5 (1)
and
@isdarkdestruction
I like your sense of anticipation, resting upon your expectations: stand by!
Jul 21, 2011
Rank: 5 / 5 (3)
That a recent merger episode occurred in these two galaxies had already been established -
NGC 680: http://iopscience....web.pdf
NGC 5557: http://www.aanda.....519MFUL
One of the questions asked is whether these two galaxies are representative of the other 260 nearby ETGs in the ATLAS sample. Too early too tell, I'd say.
In addition, the characterization of Tidal Dwarf Galaxies surrounding NGC 5557 and faint tidal debris around NGC 680 really shows off the merits of these new, deep, CFHT images. Looking forward to the completion of the survey and what surprises it may uncover in the ATLAS sample.
Jul 21, 2011
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Jul 22, 2011
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People at this address think that the Big Bang and all that it implies (superluminal recession speeds etc) is wonderful.
http://www.facebo...267?ap=1
Jul 23, 2011
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Ding ding ding ding ding! We have a winner!
Jul 23, 2011
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There's an interesting coherence between you and jsdarkdestruction.
Jul 23, 2011
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This becomes a transit zone from Source-fields,Flows,Reflectors and Protective region to Prime Functional -Cosmological Index
vidyardhicosmology[dot]blogspot[dot]com
Vidyardhi Nanduri
Jul 24, 2011
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Jul 26, 2011
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Jul 26, 2011
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I'm somehow inclined to the later option. For example, we could imagine, the stellar stream coincides with invisible dark matter stream, which stabilizes and freezes the stars in it like fiber of invisible slime.
Jul 28, 2011
Rank: 5 / 5 (1)
I see nothing compelling in the theory you keep preaching tuxford, nice try though.
Aug 07, 2011
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OK, I'll bite. How about a postulate that goes like this: "So far as we can observe, everything in the Universe orbits something else, including the largest galaxies.