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Title: The Little Cub: Discovery of an Extremely Metal-poor Star-forming Galaxy in the Local Universe

Abstract

We report the discovery of the Little Cub, an extremely metal-poor star-forming galaxy in the local universe, found in the constellation Ursa Major (a.k.a. the Great Bear). We first identified the Little Cub as a candidate metal-poor galaxy based on its Sloan Digital Sky Survey photometric colors, combined with spectroscopy using the Kast spectrograph on the Shane 3 m telescope at Lick Observatory. In this Letter, we present high-quality spectroscopic data taken with the Low Resolution Imaging Spectrometer at Keck Observatory, which confirm the extremely metal-poor nature of this galaxy. Based on the weak [O iii] λ 4363 Å emission line, we estimate a direct oxygen abundance of 12 + log(O/H) = 7.13 ± 0.08, making the Little Cub one of the lowest-metallicity star-forming galaxies currently known in the local universe. The Little Cub appears to be a companion of the spiral galaxy NGC 3359 and shows evidence of gas stripping. We may therefore be witnessing the quenching of a near-pristine galaxy as it makes its first passage about a Milky Way–like galaxy.

Authors:
; ;  [1];  [2]
  1. Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95060 (United States)
  2. Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
Publication Date:
OSTI Identifier:
22654404
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 845; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; EMISSION; GALACTIC EVOLUTION; GALAXIES; METALLICITY; MILKY WAY; OXYGEN; QUENCHING; RESOLUTION; SPECTROMETERS; SPECTROSCOPY; STARS; STRIPPING; TELESCOPES; UNIVERSE

Citation Formats

Hsyu, Tiffany, Prochaska, J. Xavier, Bolte, Michael, and Cooke, Ryan J. The Little Cub: Discovery of an Extremely Metal-poor Star-forming Galaxy in the Local Universe. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA821F.
Hsyu, Tiffany, Prochaska, J. Xavier, Bolte, Michael, & Cooke, Ryan J. The Little Cub: Discovery of an Extremely Metal-poor Star-forming Galaxy in the Local Universe. United States. doi:10.3847/2041-8213/AA821F.
Hsyu, Tiffany, Prochaska, J. Xavier, Bolte, Michael, and Cooke, Ryan J. Sun . "The Little Cub: Discovery of an Extremely Metal-poor Star-forming Galaxy in the Local Universe". United States. doi:10.3847/2041-8213/AA821F.
@article{osti_22654404,
title = {The Little Cub: Discovery of an Extremely Metal-poor Star-forming Galaxy in the Local Universe},
author = {Hsyu, Tiffany and Prochaska, J. Xavier and Bolte, Michael and Cooke, Ryan J.},
abstractNote = {We report the discovery of the Little Cub, an extremely metal-poor star-forming galaxy in the local universe, found in the constellation Ursa Major (a.k.a. the Great Bear). We first identified the Little Cub as a candidate metal-poor galaxy based on its Sloan Digital Sky Survey photometric colors, combined with spectroscopy using the Kast spectrograph on the Shane 3 m telescope at Lick Observatory. In this Letter, we present high-quality spectroscopic data taken with the Low Resolution Imaging Spectrometer at Keck Observatory, which confirm the extremely metal-poor nature of this galaxy. Based on the weak [O iii] λ 4363 Å emission line, we estimate a direct oxygen abundance of 12 + log(O/H) = 7.13 ± 0.08, making the Little Cub one of the lowest-metallicity star-forming galaxies currently known in the local universe. The Little Cub appears to be a companion of the spiral galaxy NGC 3359 and shows evidence of gas stripping. We may therefore be witnessing the quenching of a near-pristine galaxy as it makes its first passage about a Milky Way–like galaxy.},
doi = {10.3847/2041-8213/AA821F},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 845,
place = {United States},
year = {Sun Aug 20 00:00:00 EDT 2017},
month = {Sun Aug 20 00:00:00 EDT 2017}
}