Thread: First stars
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Old May 19th 18, 09:07 AM posted to sci.astro.research
jacobnavia
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Default First stars

Le 18/05/2018 Ã* 20:50, Bringfried Stecklum a écritÂ*:
On 16.05.2018 13:22, Steve Willner wrote:
A recent _Nature_ article
http://adsabs.harvard.edu/abs/2018Natur.555...67B
shows evidence that the first stars appeared by z=20, about 180 Myr
after the Big Bang. This is a preliminary result and still needs
confirmation, but it's quite intriguing. Unfortunately there does
not appear to be a free-access preprint of the article, but one of
the authors will be giving the CfA Colloquium this Thursday at 4 PM
EDT (UT-4). Colloquia are usually live-streamed; link at
https://www.cfa.harvard.edu/colloquia
or
https://www.youtube.com/channel/UCAp...xmiV95A0ChueYg
The latter link shows past colloquia but won't show the live stream
(if at all) until just a minute or two before the talk starts.


It looks the confirmation arrived quicker than thought. See ESO PR "The
onset of star formation 250 million years after the Big Bang"

https://www.eso.org/public/news/eso1815/

which also provides a link to the paper.


That's z=17. Looks nice z=17, with now an incredible bright QSO (quasar)
with 20 Billion (!) solar masses and so bright that its light arrives
directly to us, no gravitational lensing required, imagine. It is the
most brilliant object detected so far by humans.

https://arxiv.org/pdf/1805.04317.pdf

The star mentioned above has oxygen, what implies at least several
generations of stars to produce it, and then exploding and dispersing
the oxygen into space so that it slowly condenses into anew stars...

All that at z=17!

Now this thing of 20 billion solar masses at the same epoch...

20 Billion / 0.25 Gyears gives 80 solar masses swallowed by that hole
since the "big bang", on average.

But the stars needed to feed that hole must be born, and then swallowed.

If it is swallowing gas, the process is much more inefficient since gas
heats up... and stops the process.

I suppose that at z=100 with CMB temperatures over 270K star formtion is
not really possible isn't it?

Let's assume that at 135K (z = 50) star formation could begin.
That is 50 Million years after the "bang".

That leaves us with only 200 million years to build that QSO. That means
100 stars per year in average, one each 52 hours...

That is possible, will argue many people. I do not think so.

jacob

P.S. The light from the quasar should be affected y this "star rain", at
least it should oscillate when a new star is swallowed. Do we see that?