![GTC/EMIR observations of NGC 1277 Background is a Hubble Space Telescope image of the relic galaxy, NGC 1277 (Credits: NASA, ESA, M. Beasley, and P. Kehusmaa). Bottom-left shows the H-band spectrum of the relic galaxy, NGC 1277, obtained with the EMIR spectrograph (middle) at Gran Telescopio Canarias (left) (Credits: pictures of GTC and EMIR are from GTC website).](/sites/default/files/styles/crop_square_2_2_to_320px/public/images/news/Elham_figure2.jpeg?h=ecf4a2bf&itok=ydXS1VOI)
Puzzling properties of massive early-type galaxies (ETGs) emerge when studying their spectra at near-infrared (NIR) wavelengths. Massive ETGs show strong CO absorption features in their H and K band spectra that cannot be explained by state-of-the-art stellar population models. For many years, the disagreement has been attributed to the presence of intermediate-age (0.1-2 Gyr) stellar populations in these galaxies, as the NIR light of intermediate-age stellar populations is dominated by cool stars (e.g. asymptotic giant branch (AGB) stars) that show strong CO absorptions in their spectrum
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