Instructor notes: HR Diagram Inference Lab
Instructor notes not written yet
This page is a scaffold. No instructor bundle (activities, assessment items, timing notes) has been written for this demo yet, so the outline below is drawn from the demo's own description rather than from tested classroom material.
Overview
The misconceptions this demo is built to surface:
- 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.
Activities
Suggested flow (edit as needed):
- Students write a prediction before touching controls.
- Students run the play steps in pairs and record evidence.
- Whole-class debrief: claim + evidence, then model limitations.
Assessment
- 1–2 sentence explanation aligned to the “Explain” prompt.
- One claim + one piece of evidence from the demo.
Model notes (deeper)
- Main-sequence luminosity and radius use Tout et al. (1996) analytic ZAMS fits over 0.1 <= M/Msun <= 100 and 1e-4 <= Z <= 0.03.
- Theorist HR mode uses base-10 logarithmic axes: log(L/L_sun) versus log(T_eff) with hot-left orientation.
- Observer CMD mode uses M_V versus (B-V), with deterministic photometric scatter and brighter-up magnitude inversion.
- Radius guides follow Stefan-Boltzmann scaling: $$\frac{L}{L_{\odot}}=\left(\frac{R}{R_{\odot}}\right)^2\left(\frac{T_{\rm eff}}{T_{\odot}}\right)^4$$.