Re: Gemini Uncovers 'Lost City' of Stars (Forwarded)


"Andrew Yee" <ayee@xxxxxxxxxxxxxxxxxxxxxx> schreef in bericht
news:CkkNe.22749$kz6.1195284@xxxxxxxxxxxxxxxxxxxxxxxx
> Gemini Observatory
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>
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>
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> Science Contacts:
>
> Joss Bland-Hawthorn
> Anglo-Australian Observatory
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> Bruce Draine
> Princeton University
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> Ken Freeman
> Australian National University
> Canberra, Australia
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> Gemini Uncovers 'Lost City' of Stars
>
> For Immediate Release: August 10, 2005
>
> Like archaeologists unearthing a 'lost city,' astronomers using the
> 8-meter Gemini South telescope have revealed that the galaxy NGC 300 has
> a large, faint extended disk made of ancient stars, enlarging the known
> diameter of the galaxy by a factor of two or more.
>
> The finding also implies that our own Milky Way Galaxy could be much
> larger than current textbooks say. Scientists will also need to explain
> the mystery of how galaxies like NGC 300 can form with stars so far from
> their centers.
>
> The research, by an Australian and American team of scientists was just
> published in the August 10, 2005 issue of the Astrophysical Journal.
>
> The team used the Gemini Multi-Object Spectrograph on the Gemini South
> telescope in Chile, and were able to clearly resolve extremely faint
> stars in the disk up to 47,000 light-years from the galaxy's center --
> double the previously known radius of the disk. To detect these stars,
> images were obtained that went more than ten times 'deeper' than any
> previous images of this galaxy (Figure 1).
>
> "A few billion years ago the outskirts of NGC 300 were brightly lit
> suburbs that would have shown up as clearly as its inner metropolis,"
> said the paper's lead author, Professor Joss Bland-Hawthorn of the
> Anglo-Australian Observatory in Sydney, Australia. "But the suburbs have
> dimmed with time, and are now inhabited only by faint, old stars --
> stars that need large telescopes such as Gemini South to detect them."
>
> The finding has profound implications for our own galaxy since most
> current estimates put the size of our Milky Way at about 100,000
> light-years or about the size now estimated for NGC 300. "However, the
> galaxy is much more massive and brighter than NGC 300 so on this basis,
> our galaxy is also probably much larger than we previously thought --
> perhaps as much as 200,000 light-years across," said Bland-Hawthorn.

This is a very interesting finding because the subject is here visible
matter
and what this finding implies is that our galaxy contains more visible
matter
in the outer disk than original thought.
And this in turn has consequences for the amount
of darkmatter in order to explain the (flat) rotation curve of our galaxy:
If there is more visible matter than you need less dark matter.
(And maybe almost none ?)
You cannot have them both.

For more detail goto:
http://users.pandora.be/nicvroom
Goto subject 9: dark matter.
Or goto program 2
http://users.pandora.be/nicvroom/program2.htm
Or to the program written in Excell
http://users.pandora.be/nicvroom/circ11.xls.htm

Nicolaas Vroom


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