DISCOVERY OF A GAS-RICH COMPANION TO THE EXTREMELY METAL-POOR GALAXY DDO 68

John M. Cannon; Megan Johnson; Kristen B. W. McQuinn; Erik D. Alfvin; Jeremy Bailin; H. Alyson Ford; Leo Girardi; Alec S. Hirschauer; Steven Janowiecki; John J. Salzer; Angela Van Sistine; Andrew Dolphin; E. C. Elson; Baerbel Koribalski; Paola Marigo; Jessica L. Rosenberg; Philip Rosenfield; Evan D. Skillman; Aparna Venkatesan; Steven R. Warren

doi:10.1088/2041-8205/787/1/L1

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DISCOVERY OF A GAS-RICH COMPANION TO THE EXTREMELY METAL-POOR GALAXY DDO 68

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DISCOVERY OF A GAS-RICH COMPANION TO THE EXTREMELY METAL-POOR GALAXY DDO 68

John M. Cannon, Megan Johnson, Kristen B. W. McQuinn, Erik D. Alfvin, Jeremy Bailin, H. Alyson Ford, Leo Girardi, Alec S. Hirschauer, Steven Janowiecki, John J. Salzer, …

Astrophysical journal. Letters, Vol.787(1), pp.1-7

05/20/2014

DOI: 10.1088/2041-8205/787/1/L1

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Abstract

We present H I spectral-line imaging of the extremely metal-poor galaxy DDO 68. This system has a nebular oxygen abundance of only similar to 3% Z(circle dot), making it one of the most metal-deficient galaxies known in the local volume. Surprisingly, DDO 68 is a relatively massive and luminous galaxy for its metal content, making it a significant outlier in the mass-metallicity and luminosity-metallicity relationships. The origin of such a low oxygen abundance in DDO 68 presents a challenge for models of the chemical evolution of galaxies. One possible solution to this problem is the infall of pristine neutral gas, potentially initiated during a gravitational interaction. Using archival Hi spectral-line imaging obtained with the Karl G. Jansky Very Large Array, we have discovered a previously unknown companion of DDO 68. This low-mass (M-H (I) = 2.8 x 10(7) M-circle dot), recently star-forming (SFRFUV = 1.4 x 10(-3) M-circle dot yr(-1), SFRH alpha < 7 x 10(-5) M-circle dot yr(-1)) companion has the same systemic velocity as DDO 68 (V-sys = 506 km s(-1); D = 12.74 +/- 0.27 Mpc) and is located at a projected distance of similar to 42 kpc. New Hi maps obtained with the 100 m Robert C. Byrd Green Bank Telescope provide evidence that DDO 68 and this companion are gravitationally interacting at the present time. Low surface brightness Hi gas forms a bridge between these objects.

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Title: Subtitle: DISCOVERY OF A GAS-RICH COMPANION TO THE EXTREMELY METAL-POOR GALAXY DDO 68
Creators: John M. Cannon - Macalester College
Megan Johnson - Australia Telescope National Facility
Kristen B. W. McQuinn - University of Minnesota
Erik D. Alfvin - Macalester College
Jeremy Bailin - University of Alabama
H. Alyson Ford - National Radio Astronomy Observatory
Leo Girardi - Osservatorio Astronomico di Padova
Alec S. Hirschauer - Indiana University Bloomington
Steven Janowiecki - Indiana University Bloomington
John J. Salzer - Indiana University Bloomington
Angela Van Sistine - Indiana University Bloomington
Andrew Dolphin - RTX (United States)
E. C. Elson - University of Cape Town
Baerbel Koribalski - Australia Telescope National Facility
Paola Marigo - University of Padua
Jessica L. Rosenberg - George Mason University
Philip Rosenfield - University of Padua
Evan D. Skillman - University of Minnesota
Aparna Venkatesan - University of San Francisco
Steven R. Warren - University of Maryland, College Park
Resource Type: Journal article
Publication Details: Astrophysical journal. Letters, Vol.787(1), pp.1-7
DOI: 10.1088/2041-8205/787/1/L1
ISSN: 2041-8205
eISSN: 2041-8213
Publisher: Iop Publishing Ltd
Number of pages: 7
Grant note: 1211683 / Direct For Mathematical & Physical Scien; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS) NAS 5-26555 / NASA; National Aeronautics & Space Administration (NASA) 11578 / HST 1211683 / NSF; National Science Foundation (NSF)
Language: English
Date published: 05/20/2014
Academic Unit: Physics and Astronomy
Record Identifier: 9984627191502771

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