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dc.contributor.authorSánchez Almeida, J.
dc.contributor.authorMorales-Luis, A.B.
dc.contributor.authorMuñoz-Tuñón, C.
dc.contributor.authorElmegreen, D.M.
dc.contributor.authorElmegreen, B.G.
dc.contributor.authorMendez Abreu, Jairo
dc.identifier.citationSánchez Almeida , J , Morales-Luis , A B , Muñoz-Tuñón , C , Elmegreen , D M , Elmegreen , B G & Mendez Abreu , J 2014 , ' Metallicity inhomogeneities in local star-forming galaxies as a sign of recent metal-poor gas accretion ' , Astrophysical Journal , vol. 783 , no. 1 .
dc.descriptionThis work was partly funded by the Spanish Ministry for Science, project AYA 2010-21887-C04-04. J.M.A. acknowledges support from the European Research Council Starting Grant (SEDmorph; P.I. V. Wild).en
dc.description.abstractWe measure the oxygen metallicity of the ionized gas along the major axis of seven dwarf star-forming galaxies. Two of them, SDSSJ1647+21 and SDSSJ2238+14, show ≃0.5 dex metallicity decrements in inner regions with enhanced star formation activity. This behavior is similar to the metallicity drop observed in a number of local tadpole galaxies by Sánchez Almeida et al., and was interpreted as showing early stages of assembling in disk galaxies, with the star formation sustained by external metal-poor gas accretion. The agreement with tadpoles has several implications. (1) It proves that galaxies other than the local tadpoles present the same unusual metallicity pattern. (2) Our metallicity inhomogeneities were inferred using the direct method, thus discarding systematic errors usually attributed to other methods. (3) Taken together with the tadpole data, our findings suggest a threshold around one-tenth the solar value for the metallicity drops to show up. Although galaxies with clear metallicity drops are rare, the physical mechanism responsible for them may sustain a significant part of the star formation activity in the local universe. We argue that the star formation dependence of the mass-metallicity relationship, as well as other general properties followed by most local disk galaxies, is naturally interpreted as side effects of pristine gas infall. Alternatives to the metal-poor gas accretion are examined as well.
dc.relation.ispartofAstrophysical Journalen
dc.subjectGalaxies: abundancesen
dc.subjectGalaxies: dwarfen
dc.subjectGalaxies: evolutionen
dc.subjectGalaxies: formationen
dc.subjectGalaxies: kinematics and dynamicsen
dc.subjectGalaxies: structureen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.titleMetallicity inhomogeneities in local star-forming galaxies as a sign of recent metal-poor gas accretionen
dc.typeJournal articleen
dc.contributor.sponsorEuropean Research Councilen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.description.statusPeer revieweden

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