Utilizing Photometry from Multiple Sources to Mitigate Stellar Variability in Precise Radial Velocities: A Case Study of Kepler-21

We present a new analysis of Kepler-21, the brightest (V = 8.5) Kepler system with a known transiting exoplanet, Kepler-21 b. Kepler-21 b is a radius valley planet (R = 1.6\pm 0.2 R_{\oplus}) with an Earth-like composition (8.38\pm1.62 g/cc), though its mass and radius fall in the regime of possible... Show more