Star is 14.5 billion years old

[jacob navia]

http://www.sciencedaily.com/releases/2013/03/130307145103.htm

The scientific paper has the strange title:

Howard E. Bond, Edmund P. Nelan, Don A. VandenBerg, Gail H. Schaefer,
Dianne Harmer. HD 140283: A STAR IN THE SOLAR NEIGHBORHOOD THAT FORMED
SHORTLY AFTER THE BIG BANG. The Astrophysical Journal, 2013; 765 (1):
L12 DOI: 10.1088/2041-8205/765/1/L12

Interesting. In BB Cosmology the universe is 13.77 billion years old but
a star 14.5 billion years old formed AFTER the bang.

Well, cosmology is an interesting field...

The ArXiv paper is at:
http://xxx.lanl.gov/abs/1302.3180

[Mod. note: and it and the press release *both* mention the error bars
on the age... -- mjh]

[jacob navia]

Le 07/03/13 22:01, jacob navia a ecrit :

The error bars are 0.8 Billion Years in the best case, we have

14.46 - 0.8 --> 13.66 billion years with an universe of 13.7.

Using Ned's calculator we get z of 35 using H0 of 70.6.

And that is the BEST case after all down corrections are applied.

[Mod. note: they're 1-sigma error bars. -- mjh]

<QUOTE>
Employing modern theoretical isochrones, which include effects of helium
diffusion, revised nuclear reaction rates, and enhanced oxygen
abundance, we use the precise distance to infer an age of 14.46 +/- 0.31 Gyr.
<END QUOTE>

So, this would mean that the star started 300 million years before the bang.

<QUOTE>
The quoted error includes only the uncertainty in the parallax, and is
for adopted sur- face oxygen and iron abundances of [O/H] = -1.67 and
[Fe/H] = -2.40. Uncertainties in the stellar parameters and chemical
composition, especially the oxygen content, now contribute more to the
error budget for the age of HD 140283 than does its distance, increasing
the total uncertainty to about +/-0.8 Gyr.
<END QUOTE>

We see here as in the rest of the paper, the author always trying to
DECREASE the estimated age since (of course) WE KNOW that the universe
is 13.77 so a star is NOT allowed to be 14.15 since then... the bang
would have never happened.

<QUOTE>
Within the errors, the age of HD 140283 does not conflict with the age
of the Universe, 13.77 +/- 0.06 Gyr, based on the microwave background and
Hubble constant, but it must have formed soon after the big bang.
<END QUOTE>

Yes, very soon indeed. Just 300 million years after the bang.

This star is studied since a long time, and the star formation and
chemical makeup are well established. The people above just make a more
accurate distance fix using the space scope.

So, in the BEST scenario for the proponents of some "bang" 13.7 Billion
years ago, this star would have started just a few hundred million years
after the bang.

I have read always in this group that the first stars would have been
enormous and lived very short lives so that element abundance a few
hundred million years after the supposed bang would be high enough.

Is this star exceptional?

Doesn't look like. And it is so close to us that a very good parallax
can be obtained.

What a coincidence isn't it?

Just looking around a bit in our immediate neighbourhood we find a star
that should be one of the first stars of the universe.

All the paper tries desperately to bring DOWN the age. There is NO
discussion of factors that could INCREASE the age of that star.

In the cosmological calculator I used
For Ho = 70.6, OmegaM = 0.270, Omegavac = 0.730, z = 35.000

It is now 13.743 Gyr since the Big Bang.
The age at redshift z was 81.072 Myr.
The light travel time was 13.662 Gyr.
The comoving radial distance, which goes into Hubble's law, is 11910.8
Mpc or 38.848 Gly.
The comoving volume within redshift z is 7077.987 Gpc3.
The angular size distance DA is 330.9 Mpc or 1.0791 Gly.
This gives a scale of 1.604 kpc/".
The luminosity distance DL is 428788.3 Mpc or 1398.531 Gly.

Note that at that "z" we have a temperature of the CMB of 98,1 kelvins.

Stars form from cold clouds in star factories in galaxies. OK, there
were probably no galaxies and no star factories only 100 million years
after the "bang", so this star must have been formed within a completely
different environment.

Great. But the result is a very normal looking star, how AMAZING! Two
different processes lead to the SAME result.

I will stop here.

jacob at jacob dot remcomp dot fr

[Mod. note: non-ASCII characters fixed. Please do not post non-ASCII
characters; do not cut and paste from PDF unless you know what you're
doing -- mjh]

[Eric Gisse]

"Within the errors, the age of HD 140283 does not conflict with the
age of the Universe, 13.77 +/- 0.06 Gyr, based on the microwave
background and Hubble constant, but it must have formed soon after the
big bang."

I find that reading the whole abstract significantly improves the
process of understanding the abstract.

[Robert L. Oldershaw]

On Thursday, March 7, 2013 4:01:36 PM UTC-5, jacob navia wrote:
> http://www.sciencedaily.com/releases/2013/03/130307145103.htm

>
>
> [Mod. note: and it and the press release *both* mention the error bars
> on the age... -- mjh]

--------------------------------------------

[Another note: Yes, but clearly one must stretch credibility to save the phenomenon... -- rlo]

[Mod. note: The current best estimate of the age of the universe is
within the 1-sigma error bars. That doesn't cause me to have to
stretch anything. As we've discussed before in other contexts, one
object with large uncertainties does not allow very useful inferences
to be drawn -- mjh]

[Phillip Helbig---undress to reply]

In article <mt2.0-28353...@hydra.herts.ac.uk>, jacob navia

<ja...@spamsink.net> writes:

> We see here as in the rest of the paper, the author always trying to
> DECREASE the estimated age since (of course) WE KNOW that the universe
> is 13.77 so a star is NOT allowed to be 14.15 since then... the bang
> would have never happened.

Keep in mind that there are thousands of papers which support the
conventional paradigm. ONE paper on ONE star doesn't render all the
others wrong. Yes, in principle, one can disprove a theory by finding
an observation which doesn't fit, but it has to be a clear-cut case, not
one with error bars large enough to be compatible, unknown uncertainties
etc.

[Phillip Helbig---undress to reply]

In article <mt2.0-28353...@hydra.herts.ac.uk>, "Robert L.

Indeed. Those who have followed cosmology will even recall results
which disagreed at several sigma with others. Well, not all were
correct. :-|

There used to be a debate about the value of the Hubble constant. This
can also be derived from a gravitational-lens system by measuring the
time delay between separate images; a shorter delay corresponds to a
higher Hubble constant. There was a debate about the value in the
lensed quasar 0957+561. Eventually, the short delay was proved correct.
But at the height of the debate, at a conference in Li�ge, Paul
Schechter called out from the audience "Where's the problem? They agree
at 3 sigma."

[jacob navia]

Le 08/03/13 12:52, Phillip Helbig---undress to reply a écrit :

It would be nice if you could address some of the problems I pointed out
with creating a rather small star just 300 million years after the
supposed "bang":

A)
At that "z" the CMB temperature is around 100 Kelvin. Gases or matter
are at much higher temperatures. How can they condense to form a star?

Note that there can't be any galaxies or star factories at that time
unless you suppose that a galaxy, complete with star factories, can form
in 300 million years...

B)
There has been a lot of talk in this group about the "first stars" that
should have been enormous behemoths that lived only a few million years.
This star, however, is a quite normal star, nothing extraordinary, and
it is rather small.

C)
Unless we are exceptionally lucky, "first stars" must be quite abundant
today since we find one in our neighborhood.

All this if we believe the error analysis of that paper. Note that the
direct parallax age is much older than the big bang and that the
uncertainty is obtained just by postulating an uncertainty in the
evolution of oxygen concentration, (as far as I understood that paper).

jacob

[Martin Hardcastle]

In article <mt2.0-10324...@hydra.herts.ac.uk>,
jacob navia <ja...@jspamsink.org> wrote:
>Le 08/03/13 12:52, Phillip Helbig---undress to reply a ecrit :

>> In article <mt2.0-28353...@hydra.herts.ac.uk>, jacob navia
>> <ja...@spamsink.net> writes:
>A)
>At that "z" the CMB temperature is around 100 Kelvin. Gases or matter
>are at much higher temperatures. How can they condense to form a star?

By radiative cooling, as normal. Dense regions will be optically thick
to the 'CMB' (which of course at that temperature is not 'M' any more).

>Note that there can't be any galaxies or star factories at that time
>unless you suppose that a galaxy, complete with star factories, can form
>in 300 million years...

In standard cosmology, protogalaxies do of course exist at this time.

>
>B)
>There has been a lot of talk in this group about the "first stars" that
>should have been enormous behemoths that lived only a few million years.
>This star, however, is a quite normal star, nothing extraordinary, and
>it is rather small.

Yes. It's not one of the first stars, the so-called Population III;
it's a Population II star. You can tell because its elemental
abundances are not primordial; e.g. it contains some iron. Given that
the first stars would have had lifetimes only a few million years,
this isn't a problem.

(The idea that the first stars were hundreds of solar masses has been
being revised due to detailed numerical modelling, see e.g.
http://arxiv.org/abs/1111.3649 . However, they would still have had
very short lifetimes even if they had masses of only tens of solar
masses as in this paper.)

>C)
>Unless we are exceptionally lucky, "first stars" must be quite abundant
>today since we find one in our neighborhood.

So? This is what we expect. Low-mass stars formed shortly after the BB
should be around today.

>All this if we believe the error analysis of that paper. Note that the
>direct parallax age is much older than the big bang and that the
>uncertainty is obtained just by postulating an uncertainty in the
>evolution of oxygen concentration, (as far as I understood that paper).

Not 'postulating': by taking into account the *known* uncertainties in
making these measurements. See the bottom of page 10, where they
discuss different methods for estimating the oxygen abundances.
Different authors disagree about this by up to 0.23 dex (a factor
1.7). Depending on what answer you adopt, you get a different
(model-dependent) age.

Martin
--
Martin Hardcastle
School of Physics, Astronomy and Mathematics, University of Hertfordshire, UK
Please replace the xxx.xxx.xxx in the header with herts.ac.uk to mail me

[jacob navia]

Mr Hardcastle

Thank you for your answer. I will go through your points below:

Le 10/03/13 13:04, Martin Hardcastle a ecrit :

> In article <mt2.0-10324...@hydra.herts.ac.uk>,
> jacob navia <ja...@jspamsink.org> wrote:
>> Le 08/03/13 12:52, Phillip Helbig---undress to reply a ecrit :
>>> In article <mt2.0-28353...@hydra.herts.ac.uk>, jacob navia
>>> <ja...@spamsink.net> writes:
>> A)
>> At that "z" the CMB temperature is around 100 Kelvin. Gases or matter
>> are at much higher temperatures. How can they condense to form a star?
>
> By radiative cooling, as normal. Dense regions will be optically thick
> to the 'CMB' (which of course at that temperature is not 'M' any more).
>

As far as I understand this, dark clouds that generate protostars must
cool at temperatures between 10-20 Kelvins. This is possible TODAY
because the CMB is at 2.75 Kelvin.

You postulate that at a temperature 100 degrees HIGHER those clouds can
form and moreover cool enough to reach those 10K without reaching
equilibrium with the CMB in 300 million years.

This seems (to me) a very unlikely scenario.

>> Note that there can't be any galaxies or star factories at that time
>> unless you suppose that a galaxy, complete with star factories, can form
>> in 300 million years...
>
> In standard cosmology, protogalaxies do of course exist at this time.
>

In 300 million years can a galaxy (even protogalaxy) develop enough to
have star factories and all that?

Note:

The only thing that emerges from the supposed bang is a slight density
gradient. That gradient must condense, acquire enough matter etc to form
even a protogalaxy. All that in 300 million years.

This story looks increasingly unlikely, excuse me.

>>
>> B)
>> There has been a lot of talk in this group about the "first stars" that
>> should have been enormous behemoths that lived only a few million years.
>> This star, however, is a quite normal star, nothing extraordinary, and
>> it is rather small.
>
> Yes. It's not one of the first stars, the so-called Population III;
> it's a Population II star. You can tell because its elemental
> abundances are not primordial; e.g. it contains some iron. Given that
> the first stars would have had lifetimes only a few million years,
> this isn't a problem.
>

In 300 million years then, there is a "population II" or "population
III" star (you do not indicate which one).

My question is then:

WHEN did the "first stars" appear?

It is obvious that a "z" of 50 with a CMB temperature of 220 Kelvin no
molecular cloud can start at 10-20K... and that is 24 million years
after the bang.

We are getting awfully close to the bang and nothing new happens: a
completely normal star is found just 300 million years after that bang
in our neighborhood imagine.

> (The idea that the first stars were hundreds of solar masses has been
> being revised due to detailed numerical modelling, see e.g.
> http://arxiv.org/abs/1111.3649 . However, they would still have had
> very short lifetimes even if they had masses of only tens of solar
> masses as in this paper.)
>

In that same paper you cite, the first sentence is:

<quote>
Theoretical studies and detailed computer simulations show that the
cradles of the first stars were dense concentrations of primordial gas,
with masses of ∼ 1000 that of the sun. Such gas clouds formed through
radiative cooling, with hydrogen molecules at the center of a dark
matter halo of 106 solar mass (M⊙), when the age of the universe was a
few hundred million years old (1).
<end quote>

"When the age of the universe was a few hundred million years old".

How much is "a few" ?

Probably more than two, maybe 3 isn't it? :-) Let's say it is at least 2.

We are getting squeezed out... The first stars start at at least 200
million years after the bang, but we have a small and normal star formed
300 million years after the bang.

And it has IRON in it, so it is a nth generation star... All in 100
million years. (first stars at 200, this star at 300).

>> C)
>> Unless we are exceptionally lucky, "first stars" must be quite abundant
>> today since we find one in our neighborhood.
>
> So? This is what we expect. Low-mass stars formed shortly after the BB
> should be around today.
>

Sure?
How many stars were formed 300 million years after the bang?
How many stars were formed since the bang?

I think the ratio should be very small.

>> All this if we believe the error analysis of that paper. Note that the
>> direct parallax age is much older than the big bang and that the
>> uncertainty is obtained just by postulating an uncertainty in the
>> evolution of oxygen concentration, (as far as I understood that paper).
>
> Not 'postulating': by taking into account the *known* uncertainties in
> making these measurements. See the bottom of page 10, where they
> discuss different methods for estimating the oxygen abundances.
> Different authors disagree about this by up to 0.23 dex (a factor
> 1.7). Depending on what answer you adopt, you get a different
> (model-dependent) age.
>
> Martin
>

I will look deeper into that later, but I think that it wouldn't be
surprising if the oxygen concentration dates could be much OLDER than
what the author proposed.


Again, I thank you for your answer.

[Mod. note: non-ASCII character removed: please post in ASCII only --
mjh]

[Steve Willner]

In article <mt2.0-10324...@hydra.herts.ac.uk>,

jacob navia <ja...@spamsink.net> writes:
> At that "z" the CMB temperature is around 100 Kelvin. Gases or matter
> are at much higher temperatures. How can they condense to form a star?

There's no need for the formation redshift to be as high as 30.
Given the metallicity, it's probably much lower. In any case, we
don't know how star formation works locally, let alone at high z.

> Note that there can't be any galaxies or star factories at that time
> unless you suppose that a galaxy, complete with star factories, can form
> in 300 million years...

Stars probably formed before galaxies, but why do you think 300 Myr
is not enough time? Can you give a quantitative argument?

> There has been a lot of talk in this group about the "first stars" that
> should have been enormous behemoths that lived only a few million years.
> This star, however, is a quite normal star, nothing extraordinary, and
> it is rather small.

And it has non-zero metallicity; in fact, rather larger than the
lowest-metallicity stars known. See above about "how star formation
works." In particular, we can't predict the relative proportions of
low and high mass stars. Even if most of the first stars were high-
mass, it doesn't follow that all of them were.

> Unless we are exceptionally lucky, "first stars" must be quite abundant
> today since we find one in our neighborhood.

Actually the problem is the opposite: too few very old stars are seen
locally. Look up the "G-subdwarf problem."

All these comments are aside from any issues with the stellar age
measurement itself, which I haven't looked into.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123 swil...@cfa.harvard.edu
Cambridge, MA 02138 USA

[jacob navia]

Le 08/03/13 09:38, Eric Gisse a écrit :

Mr Gisse:

No. I have read the whole article and it looks like the authors have
made every effort to justify the "bang" without considering just the data.

In their paper they state that the error bars are + or minus 0.8 GY but
they ONLY consider the MINUS part that BARELY fits into a logical
framework: in the BEST case that star started approx 14.5-0.8 = 13.7
around 110 million years after the supposed bang. At that "z" (approx)
50 the cmb temperature is around 220 Kelvin, the gas and matter
temperature much higher. No stars can form at that temperature.

Even considering a time of 200 million years after the bang the
temperature is STILL too hot.

Another problem, as I stated in the discussion with Mr Hardcastle in
this same thread is that it is a very strange coincidence that we have
such a primordial star in our neighborhood since the ratio of stars
formed just 300 MY after the bang to the ratio of ALL stars formed since
the bang is really SMALL!

Number of stars formed 300 million years after the bang
------------------------------------------------------- = almost zero!
Number of stars formed SINCE the bang

We are really lucky isn't it? Just looking around we found a star so
NEAR that we can even determine exactly the distance by parallax!

Thanks for your answer Mr Gisse.

jacob

[jacob navia]

Le 12/03/13 09:32, Steve Willner a écrit :

> In article <mt2.0-10324...@hydra.herts.ac.uk>,
> jacob navia <ja...@spamsink.net> writes:
>> At that "z" the CMB temperature is around 100 Kelvin. Gases or matter
>> are at much higher temperatures. How can they condense to form a star?
>
> There's no need for the formation redshift to be as high as 30.

Well yes, there is a very strong argument: Since the age of that star is
14.46 +/- 0.8 GY in the BEST case the age of that star is:

14.46 - 0.8 = 13.66 GY

"Bang" theory supposes that the Universe is 13.77 so we have

13.77-13.66 = 0.11 GY

110 million years after the bang, i.e. you go to

http://www.astro.ucla.edu/~wright/CosmoCalc.html

and leave everything by default and put "z" to 30 you get 0.101 GY
approx what the "z" should be to get that age!

Of course I may be wrong. Explain please.

> Given the metallicity, it's probably much lower. In any case, we
> don't know how star formation works locally, let alone at high z.
>

Excuse me it CAN'T BE LOWER! That star is AT LEAST that age!

>> Note that there can't be any galaxies or star factories at that time
>> unless you suppose that a galaxy, complete with star factories, can form
>> in 300 million years...
>
> Stars probably formed before galaxies, but why do you think 300 Myr
> is not enough time? Can you give a quantitative argument?
>

Yes, I gave it in the discussion with Mr Hardcastle in this same thread.
Since at "z" 30 the CMB temperature is too high to allow the formation
of cold clouds of gas. Note that the CMB is the minimum temperature,
matter and gases have higher temperatures.

>> There has been a lot of talk in this group about the "first stars" that
>> should have been enormous behemoths that lived only a few million years.
>> This star, however, is a quite normal star, nothing extraordinary, and
>> it is rather small.
>
> And it has non-zero metallicity; in fact, rather larger than the
> lowest-metallicity stars known. See above about "how star formation
> works." In particular, we can't predict the relative proportions of
> low and high mass stars. Even if most of the first stars were high-
> mass, it doesn't follow that all of them were.
>

Precisely, the "metals" (IRON!) MUST have been formed by many previous
generation of stars so the case for a "bang" becomes even MORE complicated.

>> Unless we are exceptionally lucky, "first stars" must be quite abundant
>> today since we find one in our neighborhood.
>
> Actually the problem is the opposite: too few very old stars are seen
> locally. Look up the "G-subdwarf problem."
>

Mmm I do not follow you here, excuse me my ignorance. Maybe you can
explain a bit more?

[Dan Riley]

jacob navia <ja...@spamsink.net> writes:
> Le 12/03/13 09:32, Steve Willner a ��crit :

> > In article <mt2.0-10324...@hydra.herts.ac.uk>,
> > jacob navia <ja...@spamsink.net> writes:
> >> At that "z" the CMB temperature is around 100 Kelvin. Gases or matter
> >> are at much higher temperatures. How can they condense to form a star?
> >
> > There's no need for the formation redshift to be as high as 30.
>
> Well yes, there is a very strong argument: Since the age of that star is
> 14.46 +/- 0.8 GY in the BEST case the age of that star is:
>
> 14.46 - 0.8 = 13.66 GY

As the mod pointed out way up-thread, those are 1-sigma errors, so
there is about a 1 in 6 expectation that the real value is less than
13.66. For bounds calculations, it is customary to go out at least to
the 95% CL at 2-sigma, which, by your methodology, corresponds to a z
around 6.

A Bayesian astronomer might start with a prior that says the oldest
observed star is likely to be younger than the age of the universe.
What's the alternative prior--if there weren't a big bang, how likely
is it that the oldest observed star would be so close to the BB age,
not much older?

-dan

[jacob navia]

Thanks for your answer Mr Riley. I go to your points below.

Le 12/03/13 21:00, Dan Riley a écrit :
> jacob navia <ja...@spamsink.net> writes:
>> Le 12/03/13 09:32, Steve Willner a écrit :

>>> In article <mt2.0-10324...@hydra.herts.ac.uk>,
>>> jacob navia <ja...@spamsink.net> writes:
>>>> At that "z" the CMB temperature is around 100 Kelvin. Gases or matter
>>>> are at much higher temperatures. How can they condense to form a star?
>>>
>>> There's no need for the formation redshift to be as high as 30.
>>
>> Well yes, there is a very strong argument: Since the age of that star is
>> 14.46 +/- 0.8 GY in the BEST case the age of that star is:
>>
>> 14.46 - 0.8 = 13.66 GY
>
> As the mod pointed out way up-thread, those are 1-sigma errors, so
> there is about a 1 in 6 expectation that the real value is less than
> 13.66.

You mean 1 in 6 expectations that the error is bigger than 0.8?

Note that the error is PLUS or MINUS not MINUS ONLY!

It can also mean that the star is 14.46 + 0.8 = 15.46 GY!

Somehow the PLUS sign is ALWAYS being omitted here... Strange isn't it?

:-)

Because the first age calculations of that star went to 16 GY.

For bounds calculations, it is customary to go out at least to
> the 95% CL at 2-sigma, which, by your methodology, corresponds to a z
> around 6.
>

Sure... that would be very convenient for many people...

> A Bayesian astronomer might start with a prior that says the oldest
> observed star is likely to be younger than the age of the universe.

If there is an "AGE" of the universe. In the case of an infinite
universe that has no beginning and no end ALL stars will be ALWAYS
younger than the universe anyway!

But yes, IF the Universe starts with a bang 13.7 GY ago ALL stars MUST
be less than 13.7 GY old, and if we find ONE that is 14.5 GY old the
WHOLE hypothesis collapses with a big "bang".

> What's the alternative prior--if there weren't a big bang, how likely
> is it that the oldest observed star would be so close to the BB age,
> not much older?
>

This is not possible to answer now. Yesterday, astronomers discovered
the THIRD closest star to our sun, at 6.5 light years. Imagine. Just
next door.

We know VERY little about the universe, the first space telescope has
only 20 years and adaptive optics scopes are a few years old... NOTHING
really. We have NOT enough data to answer things like the "oldest
observed star"!

If we would have sampled (say) 20% of all stars in the Milky Way we
would be able to start answering that question.

So we are sampling basically at random. This star happens to be close
and we discovered it because it belongs to a CLASS of interesting stars
AND it is near enough to do a parallax. And BINGO!

This star is maybe older than the bang or (as the authors of the paper
CAREFULLY suggest) "it must have been formed soon after the big bang".

REALLY soon. My conviction is that it is not possible to postulate a
normal star forming just 100 million years or even 300 million years
after the supposed "bang".

Things would have been too hot still to allow for that to happen.
Note that this star was first given an age of 16 GY. Then, the value
has decreased.

Are astronomers seeing what they want to see?

It is VERY difficult to keep an open mind when many other factors
are at stake.

The first one is our (very human) PRIDE. Since we left the caves and
saw the stars, we have always had a coherent cosmology.

WE NEED THAT.

But we should remember that ALL our cosmologies have ALWAYS collapsed.

This one will be no exception.

jacob

[Steve Willner]

In article <mt2.0-3481...@hydra.herts.ac.uk>,

jacob navia <ja...@spamsink.net> writes:
> Excuse me it CAN'T BE LOWER! That star is AT LEAST that age!

See Dan Riley's post on the meaning of error bars, and bear in mind
that stated error bars tend to be too small because some causes of
error are overlooked. (I'm not saying Bond et al. have done that,
only that it's a general tendency.) The question we should really be
asking here is what is wrong with the stellar models (or maybe
observations) to give an age estimate so large. The authors (their
Table 1) suspect the oxygen abundance or the estimate of effective
temperature.

Getting back to the cosmology, the 2-sigma limit on the age
corresponds to z=6.8, 800 Myr after the Big Bang. My guess would be
that the star formed around then or a bit earlier. We see galaxies
at least as old as z=8, and there are claims for z>10, so this epoch
isn't a problem.

Do you remember a few years ago when claimed globular cluster ages
were 17 Gyr with error bars of only 1 or maybe 1.5 Gyr? We know how
that turned out. (The distances were wrong.)

> Since at "z" 30 the CMB temperature is too high to allow the formation
> of cold clouds of gas.

CMB temperature would be 81 K. Given how little we know about star
formation, I'd be reluctant to assert that star formation couldn't
happen under those conditions. Metals being absent makes it harder,
no doubt. The present view -- you can read "guess" -- is that star
formation gets started around z=15, but really nobody knows for sure.

One thing we do know is that galaxies are a lot more common at z=6
and lower than at z=8 and higher. That is, a few of the very first
stars and galaxies formed at z=8 or earlier, but the bulk of star
formation didn't get going until "cosmic high noon," around z=3 to
1.5.

> the "metals" (IRON!) MUST have been formed by many previous
> generation of stars so the case for a "bang" becomes even MORE complicated.

Core collapse SNe produce huge amounts of iron. Once you have cc
SNe, you have pretty much all the elements, though not necessarily in
today's proportions.

SW> Actually the problem is the opposite: too few very old stars are seen
SW> locally. Look up the "G-subdwarf problem."

>
> Mmm I do not follow you here

Stars less than something like 0.7 solar masses live longer than the
age of the universe. So all of them ever formed (barring rare
catastrophes) are still around and should be seen locally as "G
subdwarfs." If you calculate how many of them we should see based on
estimated star formation in the early universe -- I think primarily
based on metal production -- there aren't enough. The traditional
explanation is that the early universe produced more high-mass stars
than local star formation does ("early universe had a top-heavy IMF"
is the jargon). The high-mass stars produced the metals we see but
themselves have vanished, and the accompanying low-mass stars exist
but are rarer than calculated. This is all logically consistent, but
lacking a decent theory of star formation and metal production, it's
impossible to make quantitative predictions.

[Dan Riley]

jacob navia <ja...@spamsink.net> writes:
> > As the mod pointed out way up-thread, those are 1-sigma errors, so
> > there is about a 1 in 6 expectation that the real value is less than
> > 13.66.
>
> You mean 1 in 6 expectations that the error is bigger than 0.8?

No, 1 in 6 that it is larger on the low side. 1-sigma coverage is
68%, so there's about 1 in 3 expectation that the error is larger than
0.8. We're implicitly assuming a symmetric distribution, so 1 in 6
above and 1 in 6 below.

> > What's the alternative prior--if there weren't a big bang, how likely
> > is it that the oldest observed star would be so close to the BB age,
> > not much older?
>
> This is not possible to answer now

That seems...improbable. You clearly have some kind of prior in mind,
or you wouldn't be saying this:

> REALLY soon. My conviction is that it is not possible to postulate a
> normal star forming just 100 million years or even 300 million years
> after the supposed "bang".

-dan

[Martin Hardcastle]

In article <mt2.0-15727...@hydra.herts.ac.uk>,
jacob navia <ja...@jspamsink.org> wrote:
>Mr Hardcastle

(I spent a number of years in order no longer to have to be called
'Mr' in an academic context (-: )

>Le 10/03/13 13:04, Martin Hardcastle a ecrit :

>As far as I understand this, dark clouds that generate protostars must
>cool at temperatures between 10-20 Kelvins. This is possible TODAY
>because the CMB is at 2.75 Kelvin.
>
>You postulate that at a temperature 100 degrees HIGHER those clouds can
>form and moreover cool enough to reach those 10K without reaching
>equilibrium with the CMB in 300 million years.

a) I don't 'postulate' any of this. I'm telling you what the standard
model for this stuff is. I didn't generate it.

b) No, that's not what I'm saying. The general idea appears to be that
the cooling in the early universe happens through lines of molecular
hydrogen. In the early universe, this can happen at much higher
temperatures than are associated with molecular hydrogen today,
because there is no ultraviolet light around to dissociate it. There
are some fairly classic papers about the details of cooling through
molecular hydrogen in the early universe, see e.g. Tegmark et al
http://adsabs.harvard.edu/abs/1997ApJ...474....1T). There is no
*intrinsic* requirement that stars form out of cold gas, it just
happens to work that way in the local universe, where dust provides
both a shield from the UV and a substrate on which molecular hydrogen
can form.

>In 300 million years can a galaxy (even protogalaxy) develop enough to
>have star factories and all that?

Yes, in standard cosmology, they can. You can find this in pretty much
every paper about the early universe. Can you present a calculation to
show that they can't? Just saying 'it looks unlikely' whenever you see
something you don't like isn't science, I'm afraid.

For example, a little googling turns up this review, relevant to this
whole thread: http://arxiv.org/abs/astro-ph/0409737 . Have a look at the
calculations of the formation redshift of protogalaxies in there. Do
you spot any errors?

>We are getting squeezed out... The first stars start at at least 200
>million years after the bang, but we have a small and normal star formed
>300 million years after the bang.
>
>And it has IRON in it, so it is a nth generation star... All in 100
>million years. (first stars at 200, this star at 300).

Not a problem. Let's say the first stars (that's Population III) start
forming at 200 million years. Their lifetime is 'a few' million years,
as I already said: two or three, perhaps. They explode as supernovae
and spread iron and other heavy elements about. Second- and
subsequent-generation stars (Population II) start forming after that.
The star we are talking about is such a star. Its age is entirely
consistent with this picture.

>Sure?
>How many stars were formed 300 million years after the bang?
>How many stars were formed since the bang?
>
>I think the ratio should be very small.

But what you need to ask is: how many stars have been assessed for
being such a metal-poor star? How many spectra of stars have been
taken? And the answer is: rather a lot. Multiply that by a small ratio
and you may still get a large number.

[Eric Gisse]

On Mar 8, 2:42�am, "Robert L. Oldershaw" <rlolders...@amherst.edu>
wrote:

> On Thursday, March 7, 2013 4:01:36 PM UTC-5, jacob navia wrote:
> >http://www.sciencedaily.com/releases/2013/03/130307145103.htm
>
> > [Mod. note: and it and the press release *both* mention the error bars
> > on the age... -- mjh]
>
> --------------------------------------------
>
> [Another note: Yes, but clearly one must stretch credibility to save the phenomenon... �-- rlo]

So do you agree that when an observational result disagrees with a
theory by many standard deviations, the theory is wrong?

[Mod. note: apologies for posting delay on this and the following few
messages. I inadvertently left a copy of Outlook running on my inbox
and it decided to spam-filter a lot of s.a.r. traffic -- mjh]

[jacob navia]

Le 12/03/13 22:23, Steve Willner a écrit :

> In article <mt2.0-3481...@hydra.herts.ac.uk>,
> jacob navia <ja...@spamsink.net> writes:
>> Excuse me it CAN'T BE LOWER! That star is AT LEAST that age!
>
> See Dan Riley's post on the meaning of error bars, and bear in mind
> that stated error bars tend to be too small because some causes of
> error are overlooked. (I'm not saying Bond et al. have done that,
> only that it's a general tendency.)

I know what error bars are. They indicate the error that the scientist
that performs the observations thinks it is attached to the measurement.

Error bars are essentially that. Then, you can add statistics, 1, 2
sigma, etc. But as far as the PUBLISHED content is concerned, those
error bars are associated with the analysis the scientist does of those
error spreads.

You argue that there is a "general" tendency of misjudging the errors in
astrophysics measurements. This could be true, but would need some
data justifying your suppositions excuse me.

> The question we should really be
> asking here is what is wrong with the stellar models (or maybe
> observations) to give an age estimate so large.

Note that the possibility that the observations are correct doesn't
even get mentioned!

OF COURSE those observations are wrong, if not, the whole big bang
theory is wrong.

> The authors (their
> Table 1) suspect the oxygen abundance or the estimate of effective
> temperature.
>

Yes, you can always try something but is it science really? Let's leave
that undecided. More measurements will in the next few years confirm
what I am saying, I am not in a hurry.

> Getting back to the cosmology, the 2-sigma limit on the age
> corresponds to z=6.8, 800 Myr after the Big Bang. My guess would be
> that the star formed around then or a bit earlier. We see galaxies
> at least as old as z=8, and there are claims for z>10, so this epoch
> isn't a problem.
>

If you stretch measurements and error bars that is correct, yes.

> Do you remember a few years ago when claimed globular cluster ages
> were 17 Gyr with error bars of only 1 or maybe 1.5 Gyr? We know how
> that turned out. (The distances were wrong.)
>

Were they?

I would like the references concerning their "wrongness".


[snip]

>
> SW> Actually the problem is the opposite: too few very old stars are seen
> SW> locally. Look up the "G-subdwarf problem."
>>
>> Mmm I do not follow you here
>
> Stars less than something like 0.7 solar masses live longer than the
> age of the universe. So all of them ever formed (barring rare
> catastrophes) are still around and should be seen locally as "G
> subdwarfs." If you calculate how many of them we should see based on
> estimated star formation in the early universe -- I think primarily
> based on metal production -- there aren't enough. The traditional
> explanation is that the early universe produced more high-mass stars
> than local star formation does ("early universe had a top-heavy IMF"
> is the jargon). The high-mass stars produced the metals we see but
> themselves have vanished, and the accompanying low-mass stars exist
> but are rarer than calculated. This is all logically consistent, but
> lacking a decent theory of star formation and metal production, it's
> impossible to make quantitative predictions.
>

Thanks for your explanation. Last week astronomers discovered that the
THIRD nearest star from the sun was one of those, at only 6.5 light
years from this newsgroup... As our techniques and surveys improve we
will see more of those and maybe that problem disappears.

jacob

P.S. Re-reading some of my answers to you sound too harsh. Please note that:

1) I thank you that you answered my query.
2) I speak with the knowledge that I am just an interested person and
respect the opinions of the professionals here, even if I do not agree
with them. :-)

[Eric Flesch]

On Fri, 15 Mar 13, jacob navia <ja...@spamsink.net> wrote:
>Le 12/03/13 22:23, Steve Willner a écrit :

>> See Dan Riley's post on the meaning of error bars, and bear in mind
>> that stated error bars tend to be too small because some causes of
>> error are overlooked. (I'm not saying Bond et al. have done that,
>> only that it's a general tendency.)
>

>You argue that there is a "general" tendency of misjudging the errors in
>astrophysics measurements. This could be true, but would need some
>data justifying your suppositions excuse me.

I think there is much merit in Jacob's stance, but on this question of
error bars, for older works on material which is better understood
today, it's been observed that actual errors were typically twice the
presented standard errors, as a sweeping average. There's no reason
to think it's any different today, and this is what Steve means by
"general tendency".

[jacob navia]

Le 13/03/13 08:30, Martin Hardcastle a ecrit :

> In article <mt2.0-15727...@hydra.herts.ac.uk>,
> jacob navia <ja...@jspamsink.org> wrote:
>> Mr Hardcastle
>
> (I spent a number of years in order no longer to have to be called
> 'Mr' in an academic context (-: )
>
>> Le 10/03/13 13:04, Martin Hardcastle a ecrit :
>> As far as I understand this, dark clouds that generate protostars must
>> cool at temperatures between 10-20 Kelvins. This is possible TODAY
>> because the CMB is at 2.75 Kelvin.
>>
>> You postulate that at a temperature 100 degrees HIGHER those clouds can
>> form and moreover cool enough to reach those 10K without reaching
>> equilibrium with the CMB in 300 million years.
>

Excuse me, no offsense intended! I thought that addressing you as "Mr"
would let the discussion proceed in a calm tone but I see I got it 100%
wrong

Sorry Martin :-)

> a) I don't 'postulate' any of this. I'm telling you what the standard
> model for this stuff is. I didn't generate it.
>

Yes, I know, but the "you" was used in a general sense, not you in
particular. I am French and my english could be wrong but I was sure
you could use "you" meaning not somebody in particular but as a general
case.

> b) No, that's not what I'm saying. The general idea appears to be that
> the cooling in the early universe happens through lines of molecular
> hydrogen. In the early universe, this can happen at much higher
> temperatures than are associated with molecular hydrogen today,
> because there is no ultraviolet light around to dissociate it. There
> are some fairly classic papers about the details of cooling through
> molecular hydrogen in the early universe, see e.g. Tegmark et al
> http://adsabs.harvard.edu/abs/1997ApJ...474....1T). There is no
> *intrinsic* requirement that stars form out of cold gas, it just
> happens to work that way in the local universe, where dust provides
> both a shield from the UV and a substrate on which molecular hydrogen
> can form.
>

Interesting article. It proposes another way of creating stars in the
supposed "early" universe. That article could be a big blow for my line
of reasoning, but fortunately for me it speaks of HUGE gas clouds (more
than 1000 solar masses) that would create enormous stars. Here we are
speaking of a star smaller than the sun.

This mechanism is referenced in the article for the FIRST stars. One of
the points there is that those stars did NOT have the problem of UV
radiation since they should have been well... the first ones.

The star we are talking about however is NOT a "first" star since it
has some iron content, it is a nth generation star so it MUST be
shielded from UV radiation of the other stars by a COLD dark cloud as
stars in a current star factory.

>> In 300 million years can a galaxy (even protogalaxy) develop enough to
>> have star factories and all that?
>
> Yes, in standard cosmology, they can. You can find this in pretty much
> every paper about the early universe. Can you present a calculation to
> show that they can't? Just saying 'it looks unlikely' whenever you see
> something you don't like isn't science, I'm afraid.
>

Well, the initial density gradient must acquire enough matter from its
surroundings to form an object.

And let's calculate a bit, since you want some figures.

Suppose a big bang produced density gradient, and at its center some big
mass, atracting things in a radius of 5000 thousand light years. Our
galaxy has a radius of somewhere 50 000 light years, so a "proto"
galaxy (whatever that may be) should be a tenth of that.

A kilogram of hydrogen at 5000 light years has a fall time of

pi R ^(1.5)
--- x -------------
2 sqrt(2G(M+m))

where
R = 5000 light years = 9.4605284 x 10E15 x 5000 meters
M = 1E6 solar masses = 1.9891 x 10E30 kilograms x 10E6
m = 1 kg, let's forget that :-)
G = 6.67398 x 10E-11

I will print intermediate results to verify I did not make any mistake.
a = 9.46052*1000000000000000*5000
47302600000000000000
b = pow(a,1.5)
325332551124632433390390678348.06

M = M=1.9891E30
1989100000000000000000000000000

2*G*M = 265504272360000000000
c = sqrt(2*G*M)
16294301837.145
b/c = 19966031952531170380.610

Now we multiply by pi/2
31362569651705500132.87 seconds
993819861196.84 years

993.81 billion years

It would take our kg of hydrogen approx 1000 GIGA years to arrive to the
center...

OK, what happens if we do not have 1E6 solar masses but 1E9?

"b" above stays the same since it depends on the radius

2*G*M get's multiplied by 1000, the square root is now
515271066876.45, b/c is 631381368056973676.71
that multiplied by PI/2 is
991771533750630924.97 seconds
31427343452.94 years
31.427 Giga years.

OK?

A LOOOOOOOOOOOOOOOOOONG time :-)

And that with a density gradient having 1000 million masses of the sun!
Can those "impurities" appear in the aftermath of the big bang? Are they
compatible with the CMB smoothness?

Note that our own galaxy (not a "proto" galaxy) has a black hole at its
center of "only" 4 x 10E6 solar masses... For a mass of 1000 million
solar masses you would have to explain HOW that behemoth appears
immediately after a smooth big bang mass distribution, not an easy
task I presume.

BUT

Please correct me if I am wrong. You wanted calculations, I did some.
Are they correct?

Your move.

> For example, a little googling turns up this review, relevant to this
> whole thread: http://arxiv.org/abs/astro-ph/0409737 . Have a look at the
> calculations of the formation redshift of protogalaxies in there. Do
> you spot any errors?
>

Thanks for this reference. It is not at all bad for my point:

1) It says that the first protogalaxies will form at z = 30. This is the
age of this star!

2) Those galaxies at z=30 will form the first generation of stars:
<quote>
Taken together, these points strongly suggest that the first stars will
be very massive. Indeed, if this basic picture is correct, it is
difficult to see how accretion could be terminated early enough to
produce a solar mass star, since the predicted accretion rates
discussed earlier suggest that this mass of gas will build up in only
10-20 yr.
<end quote>

This star is smaller than the sun.

But I could have gotten something wrong of course. I will go in the next
days thorugh that paper again with more time. It is a very dense
paper and VERY long. But also it has some interesting points:

<quote>
We expect the first stars to form in small, H2-cooled protogalaxies,
with masses of 10^5-10^6 M_solar, at redshifts z = 30-40.
<end quote>

That is the redshift of this star. Yes, you can try to get it to 2 sigma
and bring it down to 6. But that is "cheating" really. And we ALL agree
at 3 sigma of course :-)

That paper is also interesting because of the openess with which the
authors discuss the myriads of parameters, assumptions (many of those
reasonable within the framework of a wrong BB theory) trying to figure
out "in silico" what happene after the supposed bang.

[Mod. note: yet again, non-ASCII characters fixed by hand... -- mjh]

[Steve Willner]

In article <mt2.0-1885...@hydra.herts.ac.uk>,

jacob navia <ja...@spamsink.net> writes:
> My conviction is that it is not possible to postulate a
> normal star forming just 100 million years or even 300 million years
> after the supposed "bang".

You might have another look at that review article by Simon Glover:
http://xxx.lanl.gov/abs/astro-ph/0409737

On Wednesday, I went to a talk where the speaker commented that if it
weren't for "feedback" (something we don't really understand though
there are ideas about it), all the gas in the Universe would have
formed into stars by z=10. The theoretical problem is not forming
stars so soon, it's delaying most star formation until z=2 or so.

[Steve Willner]

In article <mt2.0-7657...@hydra.herts.ac.uk>,

jacob navia <ja...@spamsink.net> writes:
> You argue that there is a "general" tendency of misjudging the errors in
> astrophysics measurements. This could be true, but would need some
> data justifying your suppositions excuse me.

Eric's comment is relevant. My statement was based on quite a few
years of looking at (and generating) astronomical data. You are
welcome to do your own sampling.

The tendency doesn't mean anyone is doing anything incompetent or
evil. We authors estimate error bars based on every source of error
we can think of, but obviously we don't include the error sources we
haven't thought of. Those are sometimes well outside the limits we
expect, and the "wings" of the error distribution are distinctly
higher than Gaussian.

> Note that the possibility that the observations are correct doesn't
> even get mentioned!

I thought it was implied by putting the possibility they are wrong in
parentheses. To be clear, I expect the observations themselves are
correct, though there are stated uncertainties, real uncertainties,
and as always a remote possibility of a mistake. The oxygen
abundance is known to be uncertain, and other parts of the
theoretical framework for interpreting the observations may be wrong.

> Yes, you can always try something but is it science really?

Science, at least a big part of it in my view, is keeping straight
what you know for sure, what you have reason to believe but aren't
sure of, and what is uncertain. (Obviously it's a matter of degree
of certainty, not discrete classes.) Where one puts a given
observation or theory is, to some extent, a matter of opinion, but in
general people who know about a given subject will have opinions
based on evidence and not too far apart. (There are some famous
exceptions to that last but not many.) An analogy is in professional
sports: fans can argue forever whether player A is/was better than B,
but everyone agrees that the Hall-of-Fame players are a lot better
than most others.

SW> Do you remember a few years ago when claimed globular cluster ages
SW> were 17 Gyr with error bars of only 1 or maybe 1.5 Gyr?

> I would like the references concerning their "wrongness".

Google is helpful here. See
http://www.pnas.org/content/95/1/8.full.pdf
for an early review and
http://iopscience.iop.org/0004-637X/494/1/96/fulltext/36650.text.html
for a much later summary of the evidence. There are other references
in Google and in the second citation.

I see my memory of the history wasn't quite right; better stellar
physics, not only the Hipparcos distances, contributed to the
decrease in GC ages.

> Last week astronomers discovered that the
> THIRD nearest star from the sun was one of those, at only 6.5 light
> years from this newsgroup...

Are you talking about the brown dwarf system discovered by WISE?
Brown dwarfs are quite different from G subdwarfs, and I know of no
evidence that the nearby system is old. G subdwarfs, despite the
name, are reasonably luminous and easily identified in color-
magnitude diagrams (e.g., with Hipparcos distances). I haven't
personally looked into details, but I'd be astonished if the local
measured density of G subdwarfs turns out to be wrong. (By the way,
G subdwarfs are not under-luminous for their mass. Instead they are
bluer than normal stars of the same mass because of the lack of
atomic absorption lines in their atmospheres.)

[Eric Flesch]

On Fri, 15 Mar 13, Steve Willner <wil...@cfa.harvard.edu> wrote:
>On Wednesday, I went to a talk where the speaker commented that if it
>weren't for "feedback" (something we don't really understand though
>there are ideas about it), all the gas in the Universe would have
>formed into stars by z=10.

Uh oh, "dark feedback"... ;-)

[Jos Bergervoet]

On 3/15/2013 6:45 PM, jacob navia wrote:
...

>>> Excuse me it CAN'T BE LOWER! That star is AT LEAST that age!
>>
>> See Dan Riley's post on the meaning of error bars, and bear in mind
>> that stated error bars tend to be too small because some causes of
>> error are overlooked. (I'm not saying Bond et al. have done that,
>> only that it's a general tendency.)
>
> I know what error bars are. They indicate the error that the scientist
> that performs the observations thinks it is attached to the measurement.

Pleas reconsider. That is *not* what error bars mean.
The scientists do not think so at all. They are aware
that they do not know what the error is, but only know
a probability distribution for it.

Most importantly, this probability distribution is
wider than the error bars indicate. The scientists
know that the error can lie *outside* the error bars,
and for Gaussian distributions there is about 32%
that this is the case.

Please try to understand that it is not a case of
"stretching the error bars" if someone indicates that
errors can be larger than the error bars. On the
contrary, that is exactly what error bars mean. For
errors with a Gaussian distribution they tell you:
1) There's 68% chance the error is in this range
2) There's 32% chance it is outside this range
3) There's 16% chance the error is outside this
range on the *lower* side.

In particular, this last point seems to be something
you do not like!

...

> Note that the possibility that the observations are correct doesn't
> even get mentioned!

If errors are present with a continuous probability
distribution, then the chance would be zero that the
observation is "correct" (in the sense that the
measured value is exactly the true value!) Sorry for
being pedantic, but you are asking for it. :-)

...

> OF COURSE those observations are wrong, if not, the whole big bang
> theory is wrong.

How do you mean? It sounds more as if the precise
position in time of the big bang would be a few percent
wrong. How could you derive that the "whole" of the
theory is wrong?

....

>> Getting back to the cosmology, the 2-sigma limit on the age
>> corresponds to z=6.8, 800 Myr after the Big Bang. My guess would be
>> that the star formed around then or a bit earlier. We see galaxies
>> at least as old as z=8, and there are claims for z>10, so this epoch
>> isn't a problem.
>>
>
> If you stretch measurements and error bars that is correct, yes.

This was the remark I meant. You do not need to
stretch error bars. The given error bars tell you
that there is 5% chance that the true value is twice
or more times an error bar away from the measured
value. That's more probable than throwing 2 times
6 with a dice.

But it is definitely possible that the error bars
are not entirely correct. Suppose there is a large
uncertainty in the size of the error bars, then you
will get a much bigger chance that the measured
value is off by twice the (now given) error bar.
If the given bar is too large, the 5% will drop
to almost nothing, but if it is too small the 5%
will increase quickly, with a net result that you
get *more* chance overall (that the measured value
is off by at least twice the given error bar).

No stretching is needed at all! Just accepting what
the measurement results really mean in terms of
probabilities.

--
Jos

[Eric Flesch]

On Fri, 15 Mar 13, jacob navia <ja...@spamsink.net> wrote:
>Le 13/03/13 08:30, Martin Hardcastle a ecrit :

>> (I spent a number of years in order no longer to have to be called
>> 'Mr' in an academic context (-: )
>>

>Sorry Martin :-)

That's "Dr. Hardcastle", to you...

.... joking! :-))

[Mod. note: first names are fine on this forum, I suspect! -- mjh]

[jacob navia]

Le 15/03/13 22:15, jacob navia a �crit :

> Suppose a big bang produced density gradient, and at its center some big
> mass, atracting things in a radius of 5000 thousand light years. Our
> galaxy has a radius of somewhere 50 000 light years, so a "proto"
> galaxy (whatever that may be) should be a tenth of that.
>
> A kilogram of hydrogen at 5000 light years has a fall time of
>
> pi R ^(1.5)
> --- x -------------
> 2 sqrt(2G(M+m))
>
> where
> R = 5000 light years = 9.4605284 x 10E15 x 5000 meters
> M = 1E6 solar masses = 1.9891 x 10E30 kilograms x 10E6
> m = 1 kg, let's forget that:-)
> G = 6.67398 x 10E-11
>
> I will print intermediate results to verify I did not make any mistake.
> a = 9.46052*1000000000000000*5000
> 47302600000000000000
> b = pow(a,1.5)
> 325332551124632433390390678348.06
>
> M = M=1.9891E30
> 1989100000000000000000000000000
>

*** MISTAKE *** *** MISTAKE *** MISTAKE *** MISTAKE *** MISTAKE

1989100000000000000000000000000 Kg is the mass of 1 SUN

I was speaking of 1 MILLION suns!!!

This is a HORRIBLE mistake but the error is within a square root, so the
actual error is of a factor of 1000 since 1000 x 1000 = 1 million.

> 2*G*M = 265504272360000000000
> c = sqrt(2*G*M)
> 16294301837.145
> b/c = 19966031952531170380.610
>
> Now we multiply by pi/2
> 31362569651705500132.87 seconds
> 993819861196.84 years
>
> 993.81 billion years
>

WRONG!

It is 993.81 MIILION years

> It would take our kg of hydrogen approx 1000 GIGA years to arrive to the
> center...
>

No, only 1 giga year.

> OK, what happens if we do not have 1E6 solar masses but 1E9?
>
> "b" above stays the same since it depends on the radius
>
> 2*G*M get's multiplied by 1000, the square root is now
> 515271066876.45, b/c is 631381368056973676.71
> that multiplied by PI/2 is
> 991771533750630924.97 seconds
> 31427343452.94 years
> 31.427 Giga years.
>

NO. Only 31 million years.

> OK?


No, not "OK" at all.

1) This looks now much more plausible for BB theory. A mass of 1E9 suns
would atract every kg of hydrogen at 5 000 LY in just 31 million years.

2) A mass of 1 million suns would need 1 GY.

So, it *is* possible according to this revised calculations to gather
matter quickly within the first hundred million years to form a proto
galaxy.

I apologize for this STUPID mistake again.


This will teach me not to do such kind of calculations past midnight.
This morning I spotted the error at first glance.

jacob

P.S. and I was speaking about error bars :-(

[Nicolaas Vroom]

Op woensdag 13 maart 2013 08:30:26 UTC+1 schreef Martin Hardcastle het volgende:
> In article <mt2.0-15727...@hydra.herts.ac.uk>,

>
> Yes, in standard cosmology, they can. You can find this in pretty much
> every paper about the early universe. Can you present a calculation to
> show that they can't? Just saying 'it looks unlikely' whenever you see
> something you don't like isn't science, I'm afraid.
>
> For example, a little googling turns up this review, relevant to this
> whole thread: http://arxiv.org/abs/astro-ph/0409737 . Have a look at the
> calculations of the formation redshift of protogalaxies in there. Do
> you spot any errors?

The article you mention is a joy in reading, because I think it explains
in simple language the issues that are involved.
However it also raises certain question.
1. The article starts with the sentence:
"Astronomers have found themselves in the situation of knowing more about
the state of the Universe when it was only 380000 years old then
when it was 200 million years old"
2. Later on he writes: "The evolution of the dark matter component subsequent
to the epoch of last scattering etc."
3. And: "When it comes to understanding the behaviour of the baryonic
component we are on a much shakier ground"
4. At page 5 we read: "Given a mass function of this type, is there any way to
specify when the first halo of a given mass forms"
5. At little further: "Unlike the dark matter the baryons do not initially
form structures on very small scales, since pressure forces act to suppress
the growth of small-scale perturbations etc."

The evolution of the Universe can be divided into two parts:
the period before 380000 years after the Big Bang
and the period after 380000 years.
The most important components of the first period are
darkmatter, nonbaryonic matter and the CMBR.
The most important component of the second period is
baryonic matter and the evolution of stars and galaxies.
The picture emerges that we know the first period better
more accurate, than in the second period.
IMO this is tricky.
The problem is the dividing line of 380000 years.
It is easy possible that the ground work of star building
already started during the first period and that the time scale
of star building was much shorter compared with the present.
This same strict dividing line is also assumed here:
http://background.uchicago.edu/~whu/intermediate/angular4.html
"After recombination, the photons stream unimpeded"
IMO changes in physical processes at universal scale
are continuous in nature.
As such it is difficult to accept that first photons
are a local concept and all of a sudden become global.
The local concept means that they almost don't move.
The global concept means that they can move a distance
of 13.7 billion ly in a straight line.
This all of a sudden change is difficult to accept
partly also because photons interact with mass.
It is easy to accept that just after the Big Bang this
interaction was more severe than at present but
but this change should have happened more slowly
more continuous.

Nicolaas Vroom
http://users.pandora.be/nicvroom/

[Steve Willner]

In article <mt2.0-12791...@hydra.herts.ac.uk>,

Eric Flesch <er...@flesch.org> writes:
> Uh oh, "dark feedback"... ;-)

Heh. To be fair, though, this is baryon physics, which we know for
sure we don't understand very well. The raw energy required to expel
gas and stop star formation seems to be available, but how (or when
or even whether) it couples to the gas is far from clear. Lots of
research still to be done.

Re arithmetic mistakes: we've all made them. We hope they get
corrected before making it into the refereed literature, but there's
a reason journals publish errata.

Re early star formation: the earliest galaxies are quite a bit
smaller than current ones, and smaller radii are more appropriate.
That makes the relevant free-fall time even less.

And finally: how about the Planck results? Papers are at
http://www.sciops.esa.int/index.php?project=PLANCK&page=Planck_Published_Papers
but I confess I haven't looked at them yet.

[Eric Gisse]

On Mar 23, 3:10 am, Steve Willner <will...@cfa.harvard.edu> wrote:
[...]
> And finally: how about the Planck results? Papers are athttp://www.sciops.esa.int/index.php?project=PLANCK&page=Planck_Publis...

> but I confess I haven't looked at them yet.

http://arxiv.org/abs/1303.5076

As always data rules the day. The sterile neutrino hypothesis has
officially died due to an effective neutrino count of 3.

[Steve Willner]

In article <mt2.0-1061...@hydra.herts.ac.uk>,

Eric Gisse <jow...@gmail.com> writes:
> http://arxiv.org/abs/1303.5076
>
> As always data rules the day. The sterile neutrino hypothesis has
> officially died due to an effective neutrino count of 3.

Are you sure? It looks to me as though it's still alive at the two-
sigma level. Preferred values seem to be above 3, at any rate. I
don't see a Bayesian probability estimate, which is what we'd need,
but I didn't read closely.

[Eric Gisse]

On Mar 26, 5:10 pm, Steve Willner <will...@cfa.harvard.edu> wrote:
> In article <mt2.0-1061-1364061...@hydra.herts.ac.uk>,

> Eric Gisse <jowr...@gmail.com> writes:
> > As always data rules the day. The sterile neutrino hypothesis has
> > officially died due to an effective neutrino count of 3.
>
> Are you sure? It looks to me as though it's still alive at the two-
> sigma level. Preferred values seem to be above 3, at any rate. I
> don't see a Bayesian probability estimate, which is what we'd need,
> but I didn't read closely.

The error bars are tighter than the previous WMAP results, and are
centered on a number closer to 3 than previously. The trend is not
favorable.

With the discovery of the Higgs, the standard model at < 1 TeV
energies appears to work so we don't have any theory that would make
sterile neutrinos work either.

I have neither theory or observation on my side ;)

I was never emotionally married to the notion, I just thought it
worked well because of the gaps in our understanding of
nucleosynthesis (re: why there's matter rather than photon soup) and
because of the fair-bit-off-integer value of effective neutrino
species in WMAP results.

Now, if someone has a credible idea of why a sterile neutrino or
something like it would have a diminished contribution to the neutrino
count then my interest would be renewed because 3.3 +/- 0.27 leaves
room to maneuver. Not a whole lot though.

[Mod. note: quoted text trimmed -- mjh]