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.
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.; Plez B.. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - ELETTRONICO. - 812:2(2015), pp. 160.1-160.8. [10.1088/0004-637X/812/2/160]
RED SUPERGIANTS AS COSMIC ABUNDANCE PROBES: The FIRST DIRECT METALLICITY DETERMINATION of NGC 4038 in the ANTENNAE
Lardo C.
;
2015
Abstract
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.File | Dimensione | Formato | |
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