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

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

Research output: Contribution to journal › Article › peer-review

82 Scopus citations

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 10⁶-10^7.2 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.

Original language	English (US)
Article number	108
Journal	Astrophysical Journal
Volume	822
Issue number	2
DOIs	https://doi.org/10.3847/0004-637X/822/2/108
State	Published - May 10 2016

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© 2016. The American Astronomical Society. All rights reserved.

Keywords

galaxies: ISM
galaxies: abundances
galaxies: dwarf
galaxies: evolution
galaxies: star formation

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

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Hirschauer, A. S., Salzer, J. J., Skillman, E. D., Berg, D., McQuinn, K. B. W., Cannon, J. M., Gordon, A. J. R., Haynes, M. P., Giovanelli, R., Adams, E. A. K., Janowiecki, S., Rhode, K. L., Pogge, R. W., Croxall, K. V., & Aver, E. (2016). ALFALFA DISCOVERY of the MOST METAL-POOR GAS-RICH GALAXY KNOWN: AGC 198691. Astrophysical Journal, 822(2), Article 108. https://doi.org/10.3847/0004-637X/822/2/108

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title = "ALFALFA DISCOVERY of the MOST METAL-POOR GAS-RICH GALAXY KNOWN: AGC 198691",

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.",

keywords = "galaxies: ISM, galaxies: abundances, galaxies: dwarf, galaxies: evolution, galaxies: star formation",

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

year = "2016",

month = may,

day = "10",

doi = "10.3847/0004-637X/822/2/108",

language = "English (US)",

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journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

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T1 - ALFALFA DISCOVERY of the MOST METAL-POOR GAS-RICH GALAXY KNOWN

T2 - AGC 198691

AU - Hirschauer, Alec S.

AU - Salzer, John J.

AU - Skillman, Evan D.

AU - Berg, Danielle

AU - McQuinn, Kristen B W

AU - Cannon, John M.

AU - Gordon, Alex J R

AU - Haynes, Martha P.

AU - Giovanelli, Riccardo

AU - Adams, Elizabeth A K

AU - Janowiecki, Steven

AU - Rhode, Katherine L.

AU - Pogge, Richard W.

AU - Croxall, Kevin V.

AU - Aver, Erik

PY - 2016/5/10

Y1 - 2016/5/10

N2 - 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.

AB - 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.

KW - galaxies: ISM

KW - galaxies: abundances

KW - galaxies: dwarf

KW - galaxies: evolution

KW - galaxies: star formation

UR - https://www.scopus.com/pages/publications/84969848845

UR - https://www.scopus.com/pages/publications/84969848845#tab=citedBy

U2 - 10.3847/0004-637X/822/2/108

DO - 10.3847/0004-637X/822/2/108

M3 - Article

AN - SCOPUS:84969848845

SN - 0004-637X

VL - 822

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 108

ER -

ALFALFA DISCOVERY of the MOST METAL-POOR GAS-RICH GALAXY KNOWN: AGC 198691

Abstract

Bibliographical note

Keywords

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