[ExI] ligo does it again

[John Clark]

On Thu, Sep 28, 2017 at 12:02 PM, spike <spike66 at att.net> wrote:



> ​>
>> ​> ​
>> …And how can they be so big?
>
>
>
> ​>​
> I have been going nuts trying to figure that one out too.  There couldn’t
> have been stars that size to start with I wouldn’t think,
>
>
​Today a star would have to start off its life over 150 solar masses to end
up producing a 50 solar mass Black Hole, and there are probably only 3 or 4
stars that big in the entire galaxy; but stars of that size must have been
more common in the first generation of stars because there we no heavier
elements in the cloud that condensed to form the star. Even a small
percentage of heavy elements acts like ink making the gas cloud more opaque
so when a mid sized star forms and starts to shine the light pressure
forces the gas away preventing the star from getting any bigger, but if
there are no heavier elements the cloud is more transparent and so the star
can keep growing. And for the same reason modern large stars lose well over
half their mass due to the solar wind before they die, but the first
generation would retain more of their mass. So I can understand how such
very old stars could produce some 50 solar mass Black Holes, but could they
really produce that many? I have the feeling there is more to the story
that we don't yet understand.

>
>> ​>​
>> …Nobody predicted that, just a few years ago people were saying if LIGO
>> found anything (and some said they wouldn't)…
>
>
> ​> ​
> I do confess I was one of the naysayers.
>
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​I thought it was a long shot too​, and the entire project was almost
canceled several times. Astronomers were jealous of the money spent on it
and objected to the "O" in the LIGO name claiming it wasn't a observatory
at all and was just a harebrained physics experiment.  But now most feel if
the LIGO people don't win the Nobel Prize this year there is something
wrong with the Nobel Prize judges.

I'll bet we'll hear more about great stuff found in this observation run in
the next few weeks, t
his latest ​event happened just on
August 14 and it's unusual for the super conservative LIGO people to put
out a paper so soon, I think it's because it involved VIRGO too and the
Italian machine is new and they wanted the word out that it's doing it's
job. It's too bad all 3 detectors were only online at he same time for
about a month.

  John K Clark
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