Instructor notes: Stars on the ZAMS: Mass, Metallicity, and H-R Position

What this demo is for, how long it takes, and what misconception it targets.

• Temperature alone determines total stellar luminosity.
• Main-sequence fits apply equally to giant and compact remnant stars.
• Metallicity only changes spectral lines and not bulk stellar structure.
• Logarithmic axes distort physics rather than reveal dynamic range.

Suggested flow (edit as needed):

1. Students write a prediction before touching controls.
2. Students run the play steps in pairs and record evidence.
3. Whole-class debrief: claim + evidence, then model limitations.

• 1–2 sentence explanation aligned to the “Explain” prompt.
• One claim + one piece of evidence from the demo.

• ZAMS luminosity and radius use analytic fits from Tout et al. (1996) over 0.1 <= M/Msun <= 100 and 1e-4 <= Z <= 0.03.
• Explore view uses base-10 log-log axes: $\log_{10}(T_{\rm eff}\,[\mathrm{kK}])$ and $\log_{10}(L/L_{\odot})$.
• Stefan mode exposes the explicit closure equations: $$F=\sigma T^4$$ and $$\frac{L}{L_{\odot}}=\left(\frac{R}{R_{\odot}}\right)^2\left(\frac{T_{\rm eff}}{T_{\odot}}\right)^4$$.
• Override presets intentionally bypass ZAMS constraints so evolved/compact stars can be compared with explicit warning text, and metallicity is shown as not-applied while override mode is active.

• Add a proper instructor content collection for richer notes.
• Improve station card parameter table to be demo-driven.
• Add export-results scaffolding once runtime lands.