EOS Lab: Pressure Support in Stars
draft readiness: experimental Stars ASTR201 12 min
EOS core channels + diagnostics + regime map are implemented with finite-T Fermi branches; neutron/pair-rich extensions remain planned.
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Predict
Predict
Before touching controls: in a white-dwarf-like state, which pressure channel should dominate and why?
Play
Play
- Start with Solar core and White dwarf core presets and compare P_gas, P_rad, and P_deg,e.
- At fixed density, increase temperature by about one decade and track P_rad/P_gas.
- Use T/T_F and the LTE framing chip to justify which assumptions are credible in each state.
Explain
Explain
Use one table row to explain pressure-channel dominance and one row to explain an assumption limit.
Learning goals
- Compare gas, radiation, and electron-degeneracy pressure channels using cgs units.
- Explain how composition enters EOS through mu and mu_e.
- Use T/T_F to judge when zero-temperature degeneracy assumptions are plausible.
Misconceptions targeted
- Stellar pressure support is only thermal gas pressure.
- Radiation pressure always follows aT^4/3 without assumption checks.
Model notes
- Gas pressure uses P_gas = rho k_B T/(mu m_u) with fully ionized mixture approximations for mu and mu_e.
- Radiation pressure uses an LTE-like closure with explicit caution framing for low-density/high-temperature cases.
- Finite-temperature electron pressure uses Fermi-Dirac EOS (nonrelativistic branch first, relativistic branch at larger x_F).
- Displayed degeneracy channel is P_deg,e = max(P_e,FD - n_e k_B T, 0), so classical electron pressure is not double-counted.
About this demo
A pressure-channel lab for ASTR 201 that keeps units explicit, assumptions visible, and model diagnostics tied to the same state.