NOAO >   Observing Info >   Approved Programs >   2017B-0091

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Program Information for 2017B-0091


PI: John J Salzer, Indiana U., slaz@astro.indiana.edu
Address: Astronomy Department, 727 E. Third Street, Swain West 319, Bloomington, IN 47405 USA

CoI: Alec Hirschauer, Indiana U.

Title: Spectroscopy of Ultra-Low Metallicity Star-Forming Galaxies

Abstract: We propose to acquire abundance-quality spectra for 20-30 dwarf galaxies discovered in the H$alpha$ Dots survey (e.g., Kellar et al. 2012). The low-redshift H$alpha$ Dots sample represents some of the lowest-luminosity and lowest-metallicity actively star-forming galaxies known in the local universe. There are two primary goals of this project. The first is to explore the slope of the faint end of the luminosity-metallicity (L-Z) relation. A preliminary analysis using coarse abundance estimates for the H$alpha$ Dots suggests that the L-Z relation changes slope at the lowest luminosities. We require higher precision metallicity estimates in order to verify this result. Such a slope change could signal a paradigm shift in our understanding of how chemical evolution proceeds in galaxies. The second goal is to continue the search for extremely metal deficient (XMD) galaxies, building upon our recent discovery of AGC 198691, the most metal-poor galaxy known (Hirschauer et al. 2016). Several of the H$alpha$ Dot targets are located in the portion of emission-line ratio parameter space occupied by known XMDs. The discovery of even a few additional XMDs could ultimately lead to a better understanding of the physical processes that govern the chemical evolution in these low-abundance systems.

Program Type: Standard/Extragalactic

Scheduled Nights:
Run 1 (2017B):  KP-4m/KOSMOS -- 5n on Oct 18 - Oct 22 2017


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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