We present the chemical abundance analysis of 33 red giant stars belonging to the complex stellar system Terzan 5. We confirm the discovery of two stellar populations with distinct iron abundances: a relatively metal-poor component with [Fe/H] = -0.25 ± 0.07 rms and another component with [Fe/H] = +0.27 ± 0.04 rms, exceeding in metallicity any known Galactic globular cluster (GC). The two populations also show different [α/Fe] abundance ratios. The metal-poor component has an average [α/Fe] = +0.34 ± 0.06 rms, consistent with the canonical scenario for rapid enrichment by core collapse supernovae (SNe). The metal-rich component has [α/Fe] = +0.03 ± 0.04 rms, suggesting that the gas from which it formed was polluted by both type II and type Ia SNe on a longer timescale. Neither of the two populations shows evidence of the [Al/Fe] over [O/Fe] anti-correlation that is typically observed in Galactic GCs. Because these chemical abundance patterns are unique, we propose that Terzan 5 is not a true GC, but a stellar system with a much more complex history of star formation and chemical enrichment. © 2011. The American Astronomical Society. All rights reserved. Printed in the U.S.A.
CITATION STYLE
Origlia, L., Rich, R. M., Ferraro, F. R., Lanzoni, B., Bellazzini, M., Dalessandro, E., … Beccari, G. (2011). Spectroscopy unveils the complex nature of Terzan 5. Astrophysical Journal Letters, 726(2 PART II). https://doi.org/10.1088/2041-8205/726/2/L20
Mendeley helps you to discover research relevant for your work.