We present spectroscopic observations of the nearby dwarf galaxy AGC 198691.
This object is part of the Survey of HI in Extremely Low-Mass Dwarfs (SHIELD)
project, which is a multi-wavelength study of galaxies with HI masses in the
range of 10$^6$-10$^7.2$~M$_ødot$ discovered by the ALFALFA survey. We
have obtained spectra of the lone HII region in AGC 198691 with the new
high-throughput KPNO Ohio State Multi-Object Spectrograph (KOSMOS) 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 OIII$łambda$4363 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 $\pm$ 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 HI survey; this high yield of XMD
galaxies represents a paradigm shift in the search for extremely metal-poor
galaxies.
Beschreibung
[1603.03798] ALFALFA Discovery of the Most Metal-Poor Gas-Rich Galaxy Known: AGC 198691
%0 Generic
%1 hirschauer2016alfalfa
%A Hirschauer, Alec S.
%A Salzer, John J.
%A Skillman, Evan D.
%A Berg, Danielle
%A McQuinn, Kristen B. W.
%A Cannon, John M.
%A Gordon, Alex J. R.
%A Haynes, Martha P.
%A Giovanelli, Riccardo
%A Adams, Elizabeth A. K.
%A Janowiecki, Steven
%A Rhode, Katherine L.
%A Pogge, Richard W.
%A Croxall, Kevin V.
%A Aver, Erik
%D 2016
%K dwarf low metallicity
%T ALFALFA Discovery of the Most Metal-Poor Gas-Rich Galaxy Known: AGC
198691
%U http://arxiv.org/abs/1603.03798
%X We present spectroscopic observations of the nearby dwarf galaxy AGC 198691.
This object is part of the Survey of HI in Extremely Low-Mass Dwarfs (SHIELD)
project, which is a multi-wavelength study of galaxies with HI masses in the
range of 10$^6$-10$^7.2$~M$_ødot$ discovered by the ALFALFA survey. We
have obtained spectra of the lone HII region in AGC 198691 with the new
high-throughput KPNO Ohio State Multi-Object Spectrograph (KOSMOS) 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 OIII$łambda$4363 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 $\pm$ 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 HI survey; this high yield of XMD
galaxies represents a paradigm shift in the search for extremely metal-poor
galaxies.
@misc{hirschauer2016alfalfa,
abstract = {We present spectroscopic observations of the nearby dwarf galaxy AGC 198691.
This object is part of the Survey of HI in Extremely Low-Mass Dwarfs (SHIELD)
project, which is a multi-wavelength study of galaxies with HI masses in the
range of 10$^{6}$-10$^{7.2}$~M$_{\odot}$ discovered by the ALFALFA survey. We
have obtained spectra of the lone HII region in AGC 198691 with the new
high-throughput KPNO Ohio State Multi-Object Spectrograph (KOSMOS) 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 [OIII]$\lambda$4363 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 $\pm$ 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 HI survey; this high yield of XMD
galaxies represents a paradigm shift in the search for extremely metal-poor
galaxies.},
added-at = {2016-03-15T10:23:28.000+0100},
author = {Hirschauer, Alec S. and Salzer, John J. and Skillman, Evan D. and Berg, Danielle and McQuinn, Kristen B. W. and Cannon, John M. and Gordon, Alex J. R. and Haynes, Martha P. and Giovanelli, Riccardo and Adams, Elizabeth A. K. and Janowiecki, Steven and Rhode, Katherine L. and Pogge, Richard W. and Croxall, Kevin V. and Aver, Erik},
biburl = {https://www.bibsonomy.org/bibtex/2dce35e7ff4afd6621577815273a980f9/miki},
description = {[1603.03798] ALFALFA Discovery of the Most Metal-Poor Gas-Rich Galaxy Known: AGC 198691},
interhash = {24bec1f1b9cab266ec1d41a169733f41},
intrahash = {dce35e7ff4afd6621577815273a980f9},
keywords = {dwarf low metallicity},
note = {cite arxiv:1603.03798Comment: 14 pages, 7 figures, 4 tables, accepted for publication in ApJ},
timestamp = {2016-03-15T10:23:28.000+0100},
title = {ALFALFA Discovery of the Most Metal-Poor Gas-Rich Galaxy Known: AGC
198691},
url = {http://arxiv.org/abs/1603.03798},
year = 2016
}