Top: normalized fraction of blended lines in the O2 A-band as a function of the relative velocity of the exoplanet system with respect to Earth for three spectral resolution values (R = 1 × 105, 3 × 105, and 5 × 105). The top right panel shows a zoom-in around v* = 0 km s−1. Bottom: same as the top panel, but for the O2 NIR band.