How to estimate star's mass without gravitation constant?

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Discussion Overview

The discussion revolves around methods to estimate the mass of a star without directly using the gravitational constant (G). Participants explore various approaches, including observational techniques and theoretical relationships, while questioning the feasibility of such estimations.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Some participants suggest that the spectral class of a main sequence star can provide insights into its mass based on its color.
  • Another viewpoint proposes using absolute luminosity and surface temperature, which is related to the spectral class, to calculate total mass.
  • One participant challenges the feasibility of estimating mass without G, arguing that any method ultimately relies on gravitational theories that incorporate G, including the mass-luminosity relationship.
  • A request for clarification on the original question indicates that the discussion may benefit from further elaboration on the methods proposed.

Areas of Agreement / Disagreement

Participants express differing views on the possibility of estimating a star's mass without using G, with some suggesting methods that may not require it and others asserting that all methods are inherently linked to gravitational concepts.

Contextual Notes

The discussion highlights the dependence on observational data and theoretical frameworks that involve G, suggesting limitations in the proposed methods.

smm
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hi! title tells all
 
Astronomy news on Phys.org
smm said:
hi! title tells all

Hey!

If it is a main sequence star, you can tell what spectral class it belongs to by looking at its color. Every class has certain features, among them mass.
 
Using absolute luminosity, and the surface temperature(represented by spectral class), you could calculate the total Mass.
 
Welcome to Physics Forums smm! (and a belated welcome to orange as well).

I'm not sure I understand smm's question ... no matter how you arrive at an estimate of the mass of a star, somewhere in the chain of observation and logic, you will use G.

For example, if you estimate its mass from its absolute luminosity, you are relying indirectly on G, because theories which lead to an understanding of the mass-luminosity relationship have gravity (and hence G) as a key element. Similarly, if you use a mass-luminosity relationship as a purely observational device (i.e. you've observed enough stars to plot the relationship, even if you have no idea of why it should be like that), you'll find that observations which established the mass of stars in your empirical relationship depended on G.

Perhaps you could clarify your question a bit for us please smm?
 

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