ALFALFA DISCOVERY OF THE MOST METAL-POOR GAS-RICH GALAXY KNOWN: AGC 198691

Alec S. Hirschauer; John J. Salzer; Evan D. Skillman; Danielle Berg; Kristen B. W. McQuinn; John M. Cannon; Alex J. R. Gordon; Martha P. Haynes; Riccardo Giovanelli; Elizabeth A. K. Adams; Steven Janowiecki; Katherine L. Rhode; Richard W. Pogge; Kevin V. Croxall; Erik Aver

doi:10.3847/0004-637X/822/2/108

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ALFALFA DISCOVERY OF THE MOST METAL-POOR GAS-RICH GALAXY KNOWN: AGC 198691

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ALFALFA DISCOVERY OF THE MOST METAL-POOR GAS-RICH GALAXY KNOWN: AGC 198691

Alec S. Hirschauer, John J. Salzer, Evan D. Skillman, Danielle Berg, Kristen B. W. McQuinn, John M. Cannon, Alex J. R. Gordon, Martha P. Haynes, Riccardo Giovanelli, Elizabeth A. K. Adams, …

The Astrophysical journal, Vol.822(2), pp.108-108

05/10/2016

DOI: 10.3847/0004-637X/822/2/108

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https://arxiv.org/pdf/1603.03798View

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Abstract

ABSTRACT We present spectroscopic observations of the nearby dwarf galaxy AGC 198691. This object is part of the Survey of H i in Extremely Low-Mass Dwarfs project, which is a multi-wavelength study of galaxies with H i masses in the range of 106-107.2 M , discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We have obtained spectra of the lone H ii region in AGC 198691 with the new high-throughput KPNO Ohio State Multi-Object Spectrograph on the Mayall 4 m, as well as with the Blue Channel spectrograph on the MMT 6.5 m telescope. These observations enable the measurement of the temperature-sensitive [O iii]λ4363 line and hence the determination of a "direct" oxygen abundance for AGC 198691. We find this system to be an extremely metal-deficient (XMD) system with an oxygen abundance of 12+log(O/H) = 7.02 0.03, making AGC 198691 the lowest-abundance star-forming galaxy known in the local universe. Two of the five lowest-abundance galaxies known have been discovered by the ALFALFA blind H i survey; this high yield of XMD galaxies represents a paradigm shift in the search for extremely metal-poor galaxies.

galaxies: abundances

galaxies: dwarf

galaxies: evolution

galaxies: ISM

galaxies: star formation

Details

Title: Subtitle: ALFALFA DISCOVERY OF THE MOST METAL-POOR GAS-RICH GALAXY KNOWN: AGC 198691
Creators: Alec S. Hirschauer - Indiana University Bloomington
John J. Salzer - Indiana University Bloomington
Evan D. Skillman - University of Minnesota
Danielle Berg - University of Wisconsin–Milwaukee
Kristen B. W. McQuinn - The University of Texas at Austin
John M. Cannon - Macalester College
Alex J. R. Gordon - Macalester College
Martha P. Haynes - Cornell University
Riccardo Giovanelli - Planetary Science Institute
Elizabeth A. K. Adams - Netherlands Institute for Radio Astronomy
Steven Janowiecki - International Centre for Radio Astronomy Research
Katherine L. Rhode - Indiana University Bloomington
Richard W. Pogge - The Ohio State University
Kevin V. Croxall - The Ohio State University
Erik Aver - Gonzaga University
Resource Type: Journal article
Publication Details: The Astrophysical journal, Vol.822(2), pp.108-108
DOI: 10.3847/0004-637X/822/2/108
ISSN: 0004-637X
eISSN: 1538-4357
Publisher: The American Astronomical Society
Number of pages: 13
Alternative title: ALFALFA DISCOVERY OF THE MOST METAL-POOR GAS-RICH GALAXY KNOWN: AGC 198691
Language: English
Date published: 05/10/2016
Academic Unit: Physics and Astronomy
Record Identifier: 9984627232502771

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