Effect of spectral resolving power on line bisectors. This shows a synthetic absorption line with a bisector whose shape agrees with solar measurements at very high resolving power. The line bisectors are plotted on a greatly expanded wavelength scale (see 20 m s⁻¹ legend). The black line is the fully resolved bisector, i.e., at infinite resolving power. After convolving to the spectral resolution of the NEID, HARPS-N, EXPRES, and SOLIS/ISS spectrometers, the spans of the bisectors (colored lines) are reduced from the fully resolved case but are still sufficiently prominent to serve as probes of solar activity and allow separation of center-of-mass RVs from activity-related RV variations.