Accurate oxygen abundance of interstellar gas in Mrk 71 from optical and infrared spectra

Yuguang Chen, Tucker Jones, Ryan Sanders, Dario Fadda, Jessica Sutter, Robert Minchin, Erin Huntzinger, Peter Senchyna, Daniel Stark, Justin Spilker, Benjamin Weiner, Guido Roberts-Borsani

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The heavy element content (‘metallicity’) of the Universe is a record of the total star formation history. Gas-phase metallicity in galaxies, as well as its evolution with time, is of particular interest as a tracer of accretion and outflow processes. However, metallicities from the widely used electron temperature (Te) method are typically approximately two times lower than the values based on the recombination line method. This ‘abundance discrepancy factor’ is well known and is commonly ascribed to bias due to temperature fluctuations. We present a measurement of oxygen abundance in the nearby (3.4-Mpc) system, Markarian 71, using a combination of optical and far-infrared emission lines to measure and correct for temperature fluctuation effects. Our far-infrared result is inconsistent (>2σ significance) with the metallicity from recombination lines and, instead, indicates little to no bias in the standard Te method, ruling out the long-standing hypothesis that the abundance discrepancy factor is explained by temperature fluctuations for this object. Our results provide a framework to accurately measure metallicity across cosmic history, including with recent data reaching within the first billion years, with the James Webb Space Telescope and the Atacama Large Millimeter Array.

Original languageEnglish
Pages (from-to)771-778
Number of pages8
JournalNature Astronomy
Issue number7
StatePublished - Jul 2023

Bibliographical note

Publisher Copyright:
© 2023, The Author(s), under exclusive licence to Springer Nature Limited.

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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