How this works

• Mass sets the star's initial properties using piecewise/interpolated empirical relations for ZAMS, TAMS, and giant/supergiant stages.
• Metallicity (Z) affects temperature, color, and lifetime. Higher Z = cooler, redder, longer-lived (for low-mass). A very faint colored glow is shown for non-solar metallicity.
• Age is a percentage of the star's main sequence lifetime. The star's color, size, and position change smoothly as it evolves. The progress arc around the star shows its evolutionary stage.
• The circular progress arc shows the star's evolutionary progress from birth to end-of-life, with color changes indicating different stages.
• All calculations are based on simple, widely used astrophysical scaling laws (not full MESA models). For more details, see the Atlas and Project Report pages.

Key Relations Used:

• Main Sequence Lifetime: τ_MS ∝ M^-2.5 × (1 + 2(Z - Z_☉))
• ZAMS Luminosity: L_ZAMS ∝ M^3.5
• ZAMS Radius: R_ZAMS ∝ M^0.8
• ZAMS Temperature: T_ZAMS ∝ M^0.505 × (1 - 0.2(Z - Z_☉))
• Metallicity Effect: Higher Z → cooler, redder stars with longer lifetimes
• Evolutionary Tracks: Smooth interpolation between ZAMS, TAMS, and giant/supergiant phases