# A Chandrasekhar Mass - White Dwarf

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1. Jan 10, 2017

Hello guys.

I'm working to compute de max. mass for a white dwarf through solving the hidrostatic equilibrium equations. ( The classical ones, not TOV), and using an EoS made by my own, that considers the Fermi Pressure and stuff.

When i use the EoS for a carbon white dwarf ( i do get the Chandrasekhar mass correctly, but if i use for Iron i get i bit less then it should be. ( 1,23 instead 1,46 solar masses)

So. This difference really exist or i'm getting it wrong ??

2. Jan 15, 2017

### Ken G

The most common isotope of iron has 30 neutrons to go with 26 protons, so that's 56 nucleons to 26 free electrons, whereas carbon 12 has 12 nucleons per 6 electrons. The Chandra mass is inversely proportional to the square of that ration, so is 1.16 times smaller for iron than for carbon. That seems to be what you are getting too, so I think you are correct. Physically, the more nucleons you have per electron, the stronger the gravity relative to the degeneracy pressure, so it is easier to collapse the star.

3. Jan 16, 2017