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From: "Paul.B.Andersen" <relativity@paulba.no>
Newsgroups: sci.physics.relativity
Subject: Re: Gravitational red-shifting in the biggest star. What are the real
 colors?
Date: Mon, 30 Sep 2024 17:57:33 +0200
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Den 29.09.2024 20:49, skrev rhertz:
> 
> i'm very good at reading and I'm confident about people extracting the
> correct information from the links I post. I don't censure anything.

This is the link in your OP:
https://www.space.com/41290-biggest-star.html

Quote of relevant parts:

"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."

"UY Scuti's large radius does not make it the most massive,
  or heaviest, star. That honor goes to R136a1, which weighs in
  at about 300 times the mass of the sun but only about 30 solar radii.
  UY Scuti, in comparison, is only about 30 times the mass of the sun,
  but far greater in volume."

So this link you posted give R = 1700 solar radii and
M = 30 solar masses.

But the data _you_ extracted from the link was:

Den 28.09.2024 04:34, skrev rhertz:
| 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

So no, you are not very good at reading.

People (like me) did indeed extract the right information
from the link in your posted, but YOU DID NOT!

And what's worse, you _accepted_ that the mass is 5 billion
solar masses without wondering if it was possible!
Your ignorance is unbelievable!

And what's even worse is that when I told you that you had
got the mass wrong, you responded:
"You didn't even try to read the OP, from where I extracted
  the data, idiot."

Who is the idiot? :-D

Again and again you demonstrate your inability to read
a text and understand what you read.

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

I have however looked closer for information about  UY Scuti

This is from a star catalogue:
https://www.stellarcatalog.com/stars/uy-scuti
  It gives the data:
   R = 1708 solar radii,  Mass = 8 solar masses.

This seems to be the newest (2024-03-10):
https://www.star-facts.com/uy-scuti/
Quote:
" UY Scuti is a previous record holder for the largest star known.
  The supergiant star was believed to lie at a much greater distance
  – 9,500 light-years away – and had an estimated radius of 1,708 solar
  radii. More recent studies place it much closer and give it a smaller
  size."
"The estimated mass of UY Scuti is between 7 and 10 times the mass
  of the Sun."
"UY Scuti has a radius about 909 times that of the Sun."

With M = 8 solar masses and R = 909 solar radii we get the red shift:

Δλ/λ = GM/Rc² = 1.87e-8

This is equivalent to the Doppler shift from a star receding
at the speed 5.6 m/s.

Since the radial velocity of the star is 18.33 ± 0.82 km/s,
the uncertainty in the Doppler shift due to the motion of the star
will dwarf the gravitational red shift.

You know of course how they measure the Doppler shift from
a star. Offset of absorption lines, Balmer series, etc.


> 
> ONE MORE TIME, I EXTRACT THIS PART. BE HONEST:
> 
> 
>  From Wikipedia, two different values for mass and a remarkable "MASS IS
> UNKNOWN":
> 
> https://en.wikipedia.org/wiki/UY_Scuti
> 
> The luminosity is then calculated to be 340,000 L☉ at an effective
> temperature of 3,365±134 K, giving an initial mass of 25 M☉ (possibly up
> to 40 M☉ for a non-rotating star).[4]
> .....
> 
> UY Scuti has no known companion star and so its mass is uncertain.
> However, it is expected on theoretical grounds to be between 7 and 10
> M☉.[4]
> 
> ***********************
> 
> 7, 10, 25, 1,000 M☉. Rela-astrophysicists DON'T HAVE A CLUE!
> 
> Aren't they in the club that affirm that baryonic matter in the Universe
> accounts for only 5% of what BBT/GR requires?
> 
> And these geniuses try to calculate mass by using luminosity and 150
> years old formulae. Theoretical astrophysics IS AN ABSOLUTE JOKE, since
> the times of Stefan, later with Eddington.

Don't you think Stefan–Boltzmann law is applicable today? :-D

You have demonstrated that you are utterly ignorant of astronomy
and astrophysics.

If you had more than one neuron, you wouldn't claim
that experts in a field you know _nothing_ about were idiots.


-- 
Paul

https://paulba.no/