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View Full Version : Smith's Cloud a "dark galaxy"?



jokergirl
2009-Nov-23, 01:30 PM
http://www.newscientist.com/article/mg20427354.200-dark-galaxy-crashing-into-the-milky-way.html


Dark galaxy crashing into the Milky Way

THE Milky Way's neighbourhood may be teeming with invisible galaxies, one of which appears to be crashing into our own.

In 2008, a cloud of hydrogen with a mass then estimated at about 1 million suns was found to be colliding with our galaxy. Now it appears the object is massive enough to be a galaxy itself.

Called Smith's cloud, it has managed to avoid disintegrating during its smash-up with our own, much bigger galaxy. What's more, its trajectory suggests it punched through the disc of our galaxy once before, about 70 million years ago.

To have survived, it must contain much more matter than previously thought, in order to provide enough gravity to hold it together. Calculations by Matthew Nichols and Joss Bland-Hawthorn of the University of Sydney, Australia, indicate that it has about 100 times the previously estimated mass (arxiv.org/abs/0911.0684).

Hmm. Any thoughts?

;)

Glom
2009-Nov-23, 02:15 PM
So this cloud passed through our galaxy like Anubis passing through a poor slave?

If it was 70 million years ago, would the disruption be much more visible?

Was this what wiped out the dinosaurs?

Is this what the Mayans foresaw?

loglo
2009-Nov-23, 03:38 PM
This seems to be a typical New scientist beat up. From the last paragraph of the paper:-

In essence, we have considered the prospect that the Smith Cloud constitutes a ‘dark galaxy’ where star formation never took place. ... Our model is not unique. The cloud may have been dislodged from the outer disk or confining potential of an infalling dwarf galaxy. my bold

I've read quite a few of their papers on HVC's so was surprised by the title. Guess it did its job and made me read the story!

jokergirl
2009-Nov-24, 02:34 PM
Is it just me or has the general quality of pop-sci reporting gone down a lot recently?

Maybe it has always been that bad and I just learned more, but I doubt it's only that.

;)

Cougar
2009-Nov-24, 03:59 PM
Is it just me or has the general quality of pop-sci reporting gone down a lot recently?

Yeah, for about the last 40 years.

loglo
2009-Nov-24, 05:50 PM
Is it just me or has the general quality of pop-sci reporting gone down a lot recently?

Maybe it has always been that bad and I just learned more, but I doubt it's only that.

;)

I have certainly noticed the lowering of standards of New Scientist, enough to not bother buying it anymore, even if the cover does catch my eye.