πͺ Exoplanet Transit
Watch a planet cross its star and see the photometric flux dip in the live light curve β exactly as Kepler and TESS detect distant worlds. Adjust planet size, orbital distance, inclination, and stellar limb darkening.
The Transit Method
When a planet passes in front of its star (a transit), it blocks a tiny fraction of starlight. The fractional dip in flux is ΞF/F β (Rβ/Rβ )Β². Kepler detected planets with dips as small as 84 ppm (about 0.008%). The shape of the ingress and egress encodes orbital speed, limb darkening, and impact parameter.
Detection methods
The transit method (used by
Kepler, TESS) measures the drop in brightness. It requires precise
photometry and favours close-in planets with orbital planes near our
line of sight (inclination β 90Β°).
The radial velocity method
measures Doppler shifts in stellar spectra as the star wobbles
around the centre of mass. Combining both methods gives planet
radius AND mass, hence density.
Limb darkening (parameter u)
means the stellar disc is brighter at centre than at edge. This
shapes the transit light curve β a uniform disc gives a flat bottom;
limb darkening gives a curved bottom.