Groves, Brent AllanHo, I TingKreckel, K.Meidt, Sharon E.Blanc, Guillermo ABigiel, FrankDale, Daniel AEmsellem, EricGlover, Simon C OGrasha, KathrynKewley, LisaKruijssen, J M DiederikLang, Philipp2022-05-092022-05-092041-8205http://hdl.handle.net/1885/264618We report one of the first extragalactic observations of electron temperature variations across a spiral arm. Using Multi Unit Spectroscopic Explorer mosaic observations of the nearby galaxy NGC 1672, we measure the [N ii]λ5755 auroral line in a sample of 80 H ii regions in the eastern spiral arm of NGC 1672. We discover systematic temperature variations as a function of distance perpendicular to the spiral arm. The electron temperature is lowest on the spiral arm itself and highest on the downstream side. Photoionization models of different metallicity, pressure, and age of the ionizing source are explored to understand what properties of the interstellar medium drive the observed temperature variations. An azimuthally varying metallicity appears to be the most likely cause of the temperature variations. The electron temperature measurements solidify recent discoveries of azimuthal variations of oxygen abundance based on strong lines, and rule out the possibility that the abundance variations are artifacts of the strong-line calibrations.This work is based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 1100.B-0651. J.M.D.K. gratefully acknowledges funding from the German Research Foundation (DFG) in the form of an Emmy Noether Research Group (grant No. KR4801/1-1) and the DFG Sachbeihilfe (grant No. KR4801/2-1). J.M.D.K. gratefully acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme via the ERC Starting Grant MUSTANG (grant agreement No. 714907). F.B. acknowledges funding from the European Union Horizon 2020 research and innovation programme (grant agreement No. 726384). K.K. gratefully acknowledges funding from the German Research Foundation (DFG) in the form of an Emmy Noether Research Group (grant number KR4598/2-1, PI: Kreckel).application/pdfen-AU© 2019 The authors201910.3847/2041-8213/ab4feb2020-12-27