Red supergiants as cosmic abundance probes: the first direct metallicity determination of NGC 4038 in the antennae.
LARDO C., DAVIES B., KUDRITZKI R.-P., GAZAK J.Z., EVANS C.J., PATRICK L.R., BERGEMANN M. and PLEZ B.
Abstract (from CDS):
We present a direct determination of the stellar metallicity in the close pair galaxy NGC 4038 (D = 20 Mpc) based on the quantitative analysis of moderate-resolution KMOS/Very Large Telescope spectra of three super star clusters. The method adopted in our analysis has been developed and optimized to measure accurate metallicities from atomic lines in the J-band of single red supergiant (RSG) or RSG-dominated star clusters. Hence, our metallicity measurements are not affected by the biases and poorly understood systematics inherent to strong line H ii methods, which are routinely applied to massive data sets of galaxies. We find [Z] = +0.07±0.03 and compare our measurements to H ii strong line calibrations. Our abundances and literature data suggest the presence of a flat metallicity gradient, which can be explained as redistribution of metal-rich gas following the strong interaction.
galaxies: abundances - galaxies: individual: NGC 4038,39 - galaxies: star clusters: general - methods: analytical - techniques: spectroscopic