Zoom into the ¹²CO(6, 3) line near 1.62 μm. The red lines indicate the features regions, while the blue measure the continuum. The upper panel shows the spectrum of a carbon star, Cl* NGC 121 T V8, in which the ¹²CO(5, 2) and ¹²CO(6, 3) bands are visible. The lower panel corresponds to another carbon star, 2MASS J00571214-7307045, in which the CN and C₂ lines are more prominent and overlap with the CO lines. The spectra have been normalized at 1.62 μm for display purposes.