
In Search of Dark Stars - digital55
http://www.simonsfoundation.org/quanta/20140722-in-search-of-dark-stars/
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exratione
So back when I was running numerical simulations of pop III stellar evolution
(which is rather a long time ago now), the interesting thing is that, in
comparison to pop II and I, the extreme metal paucity means that you can have
(a) stable and extremely long-lived very dim, very small stars, verging on
being warmed up gas giants, and (b) very large and extremely short-lived
stars, which will supernova or otherwise give way to instability on the order
of a few million years after core ignition.

You can then work back to speculative mass functions (distribution of mass in
the population) by asking (a) how many large, short-lived stars you need to
generate the observed metallicity of pop II, and (b) how many extremely small
dim objects you'd need to fill out the missing mass without having so many
that someone would have seen them by now. The latter is an interesting line of
thinking; what is the upper density bound on (for example) 0.1M objects to
make both the solar system's continued existence and an inability to see these
things plausible.

You can also look at the paucity of candidates for ~1M extremely low
metallicity stars (there are just a couple out there known that could be pop
III candidates) as another constraint on the pop III mass function. Any pop
III ~1M stars would have a lifetime longer than that of the universe to date,
or at least such was the case in my models.

Research on missing mass and pop III has moved on considerably from those days
of course.

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Slackwise
> Her move to Stockholm, she said, is motivated in part by the cultural
> acceptance of women in science there. “On the entire planet, as far as I can
> tell, the best place for a woman to do science is Scandinavia,” she said.

Am I wrong to think that Sweden is as wonderfully progressive as it seems?

~~~
BugBrother
>> Am I wrong to think that Sweden is as wonderfully progressive as it seems?

There are advantages/disadvantages with everything.

A consensus culture where the boss goes around and talks to people before
setting goals is very different for Americans. Like all other cultures it
works better for some areas, worse in others.

Think politically correct, group oriented. (Have you seen that anywhere else?)

Edit: Let me paraphrase it like this: "The worst of worlds, the best of
worlds". Let me give an example. It isn't good for someone to have the "wrong"
opinions on some sensitive point in a consensus culture; a low roof. [The
Swedish term is "the opinion corridor", i.e. that only a small bandwidth of
opinions are tolerated.]

Edit 2: I think that was the first time in my life I've seen the Stockholm
people described as "friendly". :-)

~~~
dalke
I was surprised as well, regarding edit 2. Then again, my heart belongs to
Gothenburg. :-)

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_kst_
> We pointed out that because the Earth moves around the sun, any dark matter
> signal you see should go up and down with the time of year, peaking in June,
> with a minimum in December.

Why June and December? (Perihelion is around January 3, if that's relevant.)

~~~
trhway
if i remember it is explained by the move against and along the dark matter
"wind" in our galaxy. Personally i think there are a lot of "wind" to be
accounted for - out galaxy moves, our Sun moves inside galaxy and the Earth
moves around Sun. So Earth definitely hits some "wind". Is it dark matter
"wind"?

~~~
_kst_
Ah, that makes sense. So the "wind" would peak when the Earth is moving
against the galactic background.

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bryanl
This is the same Freese who has proposed detecting dark matter using gold and
DNA. I have no idea if she is right or wrong, but reading about this kind of
researching is exciting to me.

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Argorak
I know this is off-topic, but anyone else had "Benson, Arizona" ringing
through their head when they read the title?

