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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: Sat, 28 Sep 2024 22:43:22 +0200
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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"
> 
> Δf/f = Δλ/λ = z = GM/c² (1/R - 1/r) = Φ(R)/c² - Φ(r)/c²
> 
> 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

The mass is 'only' ~30 times the mass of Sun

M = 30 x 1.989E+30 kg = 5.967e+31 kg

> 
> 
> Φ(R)/c² = 6,842,736.59
> 
> In comparison, Φ(RSun)/c² = 0.000002327
> 
> 
> 
> At r = 10,000,000 R = 10,077,800,000,000,000,000 m
> 
> Φ(r)/c² = 0.684273659
> 
> 
> Δf/f = Δλ/λ = z = 6,842,736
> 
> 
> The z-value can be expressed succinctly in terms of the escape velocity
> at R, since the gravitational potential is equal to half the square of
> the escape velocity, thus:
> 
> z = 1/2 (v_escape/c)²
> 
> v_escape = 3699.4 c
> 
> But then, light can escape from UY Scuti.
> 
> Yet, it was discovered in 1860.
> 
> 
> 
> WHAT IS WRONG WITH MY CALCULATIONS, BASED ON THE WIKI LINK?



-- 
Paul

https://paulba.no/