RSAA Colloquia / Seminars / Feast-of-Facts: Friday, 13 March 2015, 14:20-14:40; Duffield Lecture Theatre

Gary Da Costa

"The Ca II triplet - [Fe/H] or [Ca/H] indicator?"

The strength of the CaII triplet lines near 8500Ang in low/medium resolution spectra of red giants have been used to measure overall abundance, characterised by [Fe/H], in many stellar systems. But does the [Ca/Fe] ratio matter? Ca II triplet line strength measurements of LMC red giants that have high dispersion measurements of both [Fe/H] and [Ca/Fe] are used to investigate this question, noting that the LMC stars have quite different [Ca/Fe] from the Galactic calibration objects (globular and open clusters).