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Newsgroups: sci.physics.relativity
Subject: Re: Gravitational red-shifting in the biggest star. What are the real colors?
From: nospam@de-ster.demon.nl (J. J. Lodder)
Reply-To: jjlxa31@xs4all.nl (J. J. Lodder)
Date: Sun, 29 Sep 2024 20:20:22 +0200
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rhertz <hertz778@gmail.com> wrote:

> On Sun, 29 Sep 2024 11:42:18 +0000, Paul.B.Andersen wrote:
> 
> > Den 28.09.2024 04:34, skrev rhertz:
> >> This link illustrates a bit:
> >>
> >> https://en.wikipedia.org/wiki/Gravitational_redshift
> >>
> >> 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"
> >>
> >> ?f/f = ??/? = z = GM/c? (1/R - 1/r) = ?(R)/c? - ?(r)/c?
> >
> >   ??/? = GM/Rc?  observed at infinity  (r -> ∞)
> >
> > https://www.space.com/41290-biggest-star.html
> >>
> >> 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
> >>
> >>
> >> ?(R)/c? = 6,842,736.59
> >
> >  From whence did you get the idiotic idea that the mass
> > of UY Scuti was 5 billion solar masses? :-D
> >
> > M = 30 solar masses =  5.967e31 kg
> > R = 696340e3?1700 m = 57868e6 m
> > c = 299792458 m/s
> >
> > ??/? = GM/Rc? = 7.65e-7
> >
> > Which is less than the red shift from the Sun.
> >
> >>
> >> In comparison, ?(RSun)/c? = 0.000002327
> >
> > M = 1.989E+30 kg
> > R = 696340e3 m
> >
> > ??/? = GM/Rc? = 2.12e-6
> >
> >
> >
> >>
> >> WHAT IS WRONG WITH MY CALCULATIONS, BASED ON THE WIKI LINK?
> >
> > Now you know.
> 
> ***************************************************************
> QUOTE:
> --------------------------------------------------------------------
> The biggest star in the universe (that we know of), UY Scuti is a
> variable hypergiant with a radius around 1,700 times larger than the
> radius of the sun.
> 
> 
> To put that in perspective, the volume of almost 5 billion suns could
> fit inside a sphere the size of UY Scuti.
> 
> 
> The star lies near the center of the Milky Way, roughly 9,500
> light-years away from Earth. Located within the constellation Scutum, UY
> Scuti is a hypergiant star. Hypergiants — larger than supergiants and
> giants — are rare stars that shine very brightly. They lose much of
> their mass through fast-moving stellar winds.
> 
> 
> https://www.space.com/41290-biggest-star.html
> **************************************************************
> 
> You didn't even try to read the OP, from where I extracted the data,
> idiot.
> 
> This is another link:
> 
> Star UY Scuti is so big, you could fit 5 billion Suns inside it
> 
> https://www.skyatnightmagazine.com/space-science/uy-scuti
> 
> 
> 
> Here it's claimed that they don't have a clue about its mass:
> 
> https://en.wikipedia.org/wiki/UY_Scuti
> 
> 
> So, rela-astrophysicists come out with any shit, as they are not
> accountable for what they publish.

Reading isn't your strongest point, is it?
By Wikipedia, the best mass estimate is smaller than 10 solar masses,
with a radius probably extending beyond Mars.
This implies a negligeable gravitational red shift,
so the answer to your question is: red, red, and red,

Jan