Back

Stellar rotation and line broadening

What you are seeing: a rotating limb-darkened star and the resulting broadened absorption line. The Doppler shift on each surface element makes the approaching limb blue, the receding limb red, and the line profile is the limb-darkened-weighted sum of every shifted copy. Vary vsin⁡iv\sin i and watch the line widen and hollow out

Figure 1. Rotating star (Doppler-coloured surface) and its broadened absorption line. Method: disk-integral sum of Doppler-shifted Gaussians weighted by quadratic limb darkening.
v sin i (km/s)30
σ (intrinsic)0.012
depth0.70
inclination (°)90

WHAT TO TRY

  • Vary each control and watch the rail readouts respond.
  • Compare the diagnostic plot against the live scene.