Chandrasekhar's Limit

Plate 67 speaks for itself: “No electron holds past it.”

The Physics

A white dwarf is held up by electron degeneracy pressure. When the electrons become relativistic that pressure can no longer keep pace with gravity, so there is a maximum mass.

M_Ch ≈ (5.83 / μ_e²) M☉

• M_Ch: Chandrasekhar mass, kg
• μ_e: mean molecular weight per electron, dimensionless
• M☉: solar mass 1.989×10³⁰ kg

Ideal limit ≈ 1.46 M☉ for μ_e = 2. ≈ 1.44 M☉ is the value usually quoted.

Sources

• S. Chandrasekhar, Astrophys. J. 74, 81 (1931).
• S. L. Shapiro, S. A. Teukolsky, Black Holes, White Dwarfs and Neutron Stars (1983).

On the poster

Plate 067, “Chandrasekhar's Limit”: the pixel-art plate with its slogan “No electron holds past it.”, the key equation and the facts panel shown above. Pixelated Physics. Physics. Personified.