Spatially resolved 2.3 µm CO line spectra of Betelgeuse obtained with the Very Large Telescope Interferometer

Ohnaka et al. 2011, A&A, 529, A163

Spatial resolution = 9.8 mas, Spectral resolution = 6000

Lower panel shows the reconstructed 1-D image of Betelgeuse at the center of one of the CO absorption lines. As the black dot moves across the star's image, the spatially resolved spectrum at each position is shown in red in the upper panel (black line shows the spatially unresolved spectrum). Note the prominent emission from the extended atmosphere (at positions <-20 mas and >20 mas).