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Red supergiants as luminous beacons of cosmic chemical abundances : the infrared j-band spectroscopic technique

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Item Summary

Title: Red supergiants as luminous beacons of cosmic chemical abundances : the infrared j-band spectroscopic technique
Authors: Gazak, Jonathan Zachary
Keywords: metallicity
Issue Date: Aug 2014
Publisher: [Honolulu] : [University of Hawaii at Manoa], [August 2014]
Abstract: A new spectroscopic method has been developed and tested which, with the advent of the next generation of 30 meter class telescopes, will enable the study of the chemical evolution of galaxies through the spectroscopy of individual red supergiant stars out to the Coma cluster of galaxies. This J{band (1.165-1.215 m) technique requires modest spectral resolutions of = 3000, enabling multi object spectroscopy using existing 8 meter telescopes (Keck, VLT) and future \extremely large telescopes" such as the Thirty Meter Telescope.
We demonstrate the power of the technique and study its limitations with high spectral resolution observations of the galactic h and Persei clusters and then set our sights outward. We observe a population of RSGs in M31 using MOSFIRE on Keck and measure the central metallicity and gradient using individual supergiants in NGC 300 at 1.9 Mpc with KMOS on the VLT.
Following these successes we demonstrate an extension of the technique by proving that the J{band method is applicable to the integrated light of super star clusters. These distant, massive coeval ensembles of stars present as red supergiants photometrically and spectroscopically when the first such stars evolve after roughly six million years. We provide a photometric technique to select properly aged clusters and apply the technique to two test cases, a super-solar cluster in M83 and a sub-solar cluster in NGC 6946. After the successful applications to those clusters we observed three super star clusters in the Antennae galaxies at 20 Mpc and extract metallicity information from their J{band spectra without difficulty. This application over such a distance is a stunning success for a stellar chemical abundance technique and with it in hand we o er the J{band technique as powerful new tool for the study of galaxy evolution and the chemical enrichment of a significant volume of the local universe.
Description: Ph.D. University of Hawaii at Manoa 2014.
Includes bibliographical references.
Rights: All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections:Ph.D. - Astronomy

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