Again, Brent, I'm kicking myself for getting away from space-based SF
writing... thanks for the post. Fascinating to contemplate.
On Fri, Jul 2, 2010 at 11:19 PM, brent wodehouse
brent_wodeho...@thefence.us wrote:
http://www.space.com/scienceastronomy/milky-way-ancient-stars-collisions-100701.html
Some Ancient Stars In Milky Way Were Born Elsewhere
By Zoe Macintosh
SPACE.com Staff Writer
posted: 01 July 2010
Our Milky Way galaxy snatched up many of its most ancient stars from
smaller galaxies that shredded each other in violent collisions, a new
study suggests.
Using new supercomputer simulations, researchers found that some ancient
Milky Way stars did not form natively with the rest of the galaxy about 10
billion years ago. Instead, they are actually the leftovers from other
galaxies that collided about 5 billion years ago.
These stars make up some of the residents in the Milky Way's stellar halo,
which extends above and below the spiral galaxy's main disk, researchers
said.
Effectively we became galactic archaeologists, hunting out the likely
sites where ancient stars could be scattered around the galaxy, said
researcher and post graduate student Andrew Cooper of the Institute of
Computational Cosmology at Durham University in the United Kingdom.
Like ancient rock strata that reveal the history of Earth, the stellar
halo preserves a record of a dramatic primeval period in the life of the
Milky Way which ended long before the sun was born, he added.
The new simulations began about 13 billion years ago, just after the
universe began, and then used universal laws of physics to chart how the
gravitational attraction of the galaxies' dark matter halos accumulated
stars over time.
Dark matter halos are regions of invisible matter around a galaxy which
astronomers only infer exist because of their gravitational effects on
visible matter.
The simulations are a blueprint for galaxy formation, said researcher
Carlos Frenk, director of the Institute of Computational Cosmology at
Durham.
Frenk said the simulations reveal clues into the early, violent history
of the Milky Way galaxy.
Researchers credited the unusually high resolution of the new simulation
for its results. Capable of zooming in on the fine details of galaxy
unraveling, the simulations showed streams of stars being pulled from
clusters due to the gravity of hidden dark matter.
Most surprising was the similarity between the simulated results and real
observations, said Cooper.
This shows that the cold dark matter model gives a convincing match to
the real universe not just on very large scales, but also for individual
Milky Way-like galaxies, he told SPACE.com.
The cold dark matter model is the current standard model of cosmology,
which depicts galaxy formation in the universe as a process primarily
arising from the clumping of dark matter.
The research is detailed in the journal Monthly Notices of the Royal
Astronomical Society.
--
If all the world's a stage and we are merely players, who the bloody hell
wrote the script? -- Charles E Grant
http://www.youtube.com/watch?v=fQUxw9aUVik
