GAS METALLICITIES IN THE EXTENDED DISKS OF NGC 1512 AND NGC 3621. CHEMICAL SIGNATURES OF METAL MIXING OR ENRICHED GAS ACCRETION?

• Published in: The Astrophysical journal Vol. 750; no. 2; pp. 1 - 20
• Main Authors: Bresolin, Fabio, Kennicutt, Robert C, Ryan-Weber, Emma
• Format: Journal Article
• Language: English
• Published: United States 10.05.2012
• Subjects: Accretion disks; ASTRONOMY; ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; COSMIC DUST; ELEMENT ABUNDANCE; EMISSION SPECTRA; Encounters; Enrichment; EXCITATION; GALACTIC EVOLUTION; GALAXIES; GAS FLOW; H II regions; Interacting galaxies; MASS; Mathematical models; MATHEMATICAL SOLUTIONS; Metallicity; METALS; NEBULAE; Signatures; STARS; VARIATIONS
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/750/2/122

We have obtained spectra of 135 H II regions located in the inner and extended disks of the spiral galaxies NGC 1512 and NGC 3621, spanning the range of galactocentric distances 0.2-2 x R[sub 25]. In the case of the interacting galaxy NGC 1512 we find a number of H II regions with peculiar metallicity for their radius, a result which can be interpreted by gas flows activated by the gravitational encounter with NGC 1510. We discuss the possibility that metal transport mechanisms from the inner disks lead to metal pollution of the outer disks. Gas accretion from the intergalactic medium, enriched by outflows, offers an alternative solution, justified within the framework of hydrodynamic simulations of galaxy evolution. Specific model predictions of the chemical enrichment and the flat gradients in extended disks of nearby galaxies will be valuable to discriminate between these different scenarios.