Re: Gravitational red-shifting in the biggest star. What are the real colors?

On Sun, 29 Sep 2024 13:57:22 +0000, J. J. Lodder wrote:

Paul.B.Andersen <relativity@paulba.no> wrote:
>

Den 28.09.2024 04:34, skrev rhertz:

This link illustrates a bit:
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https://en.wikipedia.org/wiki/Gravitational_redshift
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Using the most common formula from that link: "To first approximation,
gravitational redshift is proportional to the difference in
gravitational potential divided by the speed of light squared"
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?f/f = ??/? = z = GM/c? (1/R - 1/r) = ?(R)/c? - ?(r)/c?

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  ??/? = GM/Rc?  observed at infinity  (r -> ∞)
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https://www.space.com/41290-biggest-star.html

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G = 6.6743E?11 m^3 kg^?1 s^?2
M = 5E+09 x 1.989E+30 Kg = 9.945E+39 Kg
R = 1,700 x 634,000 Km = 1,077,800,000,000 m
>
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?(R)/c? = 6,842,736.59

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 From whence did you get the idiotic idea that the mass
of UY Scuti was 5 billion solar masses? :-D
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M = 30 solar masses =  5.967e31 kg
R = 696340e3?1700 m = 57868e6 m
c = 299792458 m/s
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??/? = GM/Rc? = 7.65e-7
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Which is less than the red shift from the Sun.
>

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In comparison, ?(RSun)/c? = 0.000002327

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M = 1.989E+30 kg
R = 696340e3 m
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??/? = GM/Rc? = 2.12e-6
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>
>

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WHAT IS WRONG WITH MY CALCULATIONS, BASED ON THE WIKI LINK?

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Now you know.

>
He is looking for trouble where none exists.
Even for neutron stars you get a nice finite gravitational redshift,
which is 'easily' observable. For example:
<https://pubmed.ncbi.nlm.nih.gov/12422210/>
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They find a redshift value of z = 0.35 ,
which is consistent with standard neutron star models,
(but not with some exotic ones)
>
Jan
>
(such a large gravitational redshift dwarfs any possible Doppler shift)

/////////////////////////////////////////////////////////////////////
You forgot to read this, don't you? I posted it two posts above.
............................
In 2021, Mediavilla (IAC, Spain) & Jiménez-Vicente (UGR, Spain) were
able to use measurements of the gravitational redshift in quasars up to
cosmological redshift of z ≈ 3 to confirm the predictions of Einstein's
equivalence principle and the lack of cosmological evolution within
13%.[28]
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