ABSTRACT The recently computed ExoMol line lists for isotopologues of AlH are used to analyse the blue spectrum (4000–4500 Å) Proxima Cen (M5.5 V). Comparison observed and spectra enables identification a large number 27AlH lines A 1? –X 1?+ band system: spectral range covering 1-0, 0-0, 1-1 bands dominated by clearly resolved lines. We reveal diffuse nature transitions close dissociation limit...