Effect of star-spot water vapor on CC detections of exoplanetary water. Three CC functions are shown, for no spots, and 2% and 5% spot filling fractions. The CC functions are displaced in velocity (and also in the Y-axis) to illustrate them without overlap, and the star-spot velocity is set at –70 km s^–1 relative to the planet, so that their CC peaks do not overlap. (In the case of most real M-dwarf stars, the CC peaks from the planet and star spot would be closely coincident). Triangles mark the signal from water in the exoplanet, and the magenta lines mark the signal from water in the star spot. This is for the M6V case, with star spots 600 K cooler than the photosphere.