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; Léo 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

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, Léo 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

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

22 Scopus citations

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 3% Z , 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 H I 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 ( = 2.8 × 10 ⁷ M ), recently star-forming (SFRFUV = 1.4 × 10^-3 M yr^-1, SFRHα < 7 × 10^-5 M 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 42 kpc. New H I 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 H I gas forms a bridge between these objects.

Original language	English (US)
Article number	L1
Journal	Astrophysical Journal Letters
Volume	787
Issue number	1
DOIs	https://doi.org/10.1088/2041-8205/787/1/L1
State	Published - May 20 2014
Externally published	Yes

Keywords

galaxies: dwarf
galaxies: evolution
galaxies: individual (DDO 68, DDO 68 C)
galaxies: irregular

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1088/2041-8205/787/1/L1

Cite this

Cannon, J. M., Johnson, M., McQuinn, K. B. W., Alfvin, E. D., Bailin, J., Ford, H. A., Girardi, L., Hirschauer, A. S., Janowiecki, S., Salzer, J. J., Van Sistine, A., Dolphin, A., Elson, E. C., Koribalski, B., Marigo, P., Rosenberg, J. L., Rosenfield, P., Skillman, E. D., Venkatesan, A., & Warren, S. R. (2014). Discovery of a gas-rich companion to the extremely metal-poor galaxy DDO 68. Astrophysical Journal Letters, 787(1), Article L1. https://doi.org/10.1088/2041-8205/787/1/L1

Cannon, JM, Johnson, M, McQuinn, KBW, Alfvin, ED, Bailin, J, Ford, HA, Girardi, L, Hirschauer, AS, Janowiecki, S, Salzer, JJ, Van Sistine, A, Dolphin, A, Elson, EC, Koribalski, B, Marigo, P, Rosenberg, JL, Rosenfield, P, Skillman, ED, Venkatesan, A & Warren, SR 2014, 'Discovery of a gas-rich companion to the extremely metal-poor galaxy DDO 68', Astrophysical Journal Letters, vol. 787, no. 1, L1. https://doi.org/10.1088/2041-8205/787/1/L1

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title = "Discovery of a gas-rich companion to the extremely metal-poor galaxy DDO 68",

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 3% Z , 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 H I 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 ( = 2.8 × 10 7 M ), recently star-forming (SFRFUV = 1.4 × 10-3 M yr-1, SFRHα < 7 × 10-5 M 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 42 kpc. New H I 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 H I gas forms a bridge between these objects.",

keywords = "galaxies: dwarf, galaxies: evolution, galaxies: individual (DDO 68, DDO 68 C), galaxies: irregular",

author = "Cannon, {John M.} and Megan Johnson and McQuinn, {Kristen B.W.} and Alfvin, {Erik D.} and Jeremy Bailin and Ford, {H. Alyson} and L{\'e}o Girardi and Hirschauer, {Alec S.} and Steven Janowiecki and Salzer, {John J.} and {Van Sistine}, Angela and Andrew Dolphin and Elson, {E. C.} and Baerbel Koribalski and Paola Marigo and Rosenberg, {Jessica L.} and Philip Rosenfield and Skillman, {Evan D.} and Aparna Venkatesan and Warren, {Steven R.}",

year = "2014",

month = may,

day = "20",

doi = "10.1088/2041-8205/787/1/L1",

language = "English (US)",

volume = "787",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

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T1 - Discovery of a gas-rich companion to the extremely metal-poor galaxy DDO 68

AU - Cannon, John M.

AU - Johnson, Megan

AU - McQuinn, Kristen B.W.

AU - Alfvin, Erik D.

AU - Bailin, Jeremy

AU - Ford, H. Alyson

AU - Girardi, Léo

AU - Hirschauer, Alec S.

AU - Janowiecki, Steven

AU - Salzer, John J.

AU - Van Sistine, Angela

AU - Dolphin, Andrew

AU - Elson, E. C.

AU - Koribalski, Baerbel

AU - Marigo, Paola

AU - Rosenberg, Jessica L.

AU - Rosenfield, Philip

AU - Skillman, Evan D.

AU - Venkatesan, Aparna

AU - Warren, Steven R.

PY - 2014/5/20

Y1 - 2014/5/20

N2 - We present H I spectral-line imaging of the extremely metal-poor galaxy DDO 68. This system has a nebular oxygen abundance of only 3% Z , 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 H I 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 ( = 2.8 × 10 7 M ), recently star-forming (SFRFUV = 1.4 × 10-3 M yr-1, SFRHα < 7 × 10-5 M 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 42 kpc. New H I 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 H I gas forms a bridge between these objects.

AB - We present H I spectral-line imaging of the extremely metal-poor galaxy DDO 68. This system has a nebular oxygen abundance of only 3% Z , 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 H I 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 ( = 2.8 × 10 7 M ), recently star-forming (SFRFUV = 1.4 × 10-3 M yr-1, SFRHα < 7 × 10-5 M 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 42 kpc. New H I 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 H I gas forms a bridge between these objects.

KW - galaxies: dwarf

KW - galaxies: evolution

KW - galaxies: individual (DDO 68, DDO 68 C)

KW - galaxies: irregular

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UR - http://www.scopus.com/inward/citedby.url?scp=84900439697&partnerID=8YFLogxK

U2 - 10.1088/2041-8205/787/1/L1

DO - 10.1088/2041-8205/787/1/L1

M3 - Article

AN - SCOPUS:84900439697

SN - 2041-8205

VL - 787

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 1

M1 - L1

ER -

Discovery of a gas-rich companion to the extremely metal-poor galaxy DDO 68

Abstract

Keywords

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