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The VMC survey – XXXIX: Mapping metallicity trends in the Small Magellanic Cloud using near-infrared passbands

Choudhury, Samyaday; de Grijs, Richard; Rubele, Stefano; Bekki, Kenji; Cioni, Maria-Rosa L; Ivanov, Valentin D; Van Loon, Jacco Th; Niederhofer, Florian; Oliveira, Joana M; Ripepi, Vincenzo

The VMC survey – XXXIX: Mapping metallicity trends in the Small Magellanic Cloud using near-infrared passbands Thumbnail


Authors

Samyaday Choudhury

Richard de Grijs

Stefano Rubele

Kenji Bekki

Maria-Rosa L Cioni

Valentin D Ivanov

Florian Niederhofer

Vincenzo Ripepi



Abstract

We have derived high spatial resolution metallicity maps covering ~42 deg2 across the Small Magellanic Cloud (SMC) in an attempt to understand its metallicity distribution and gradients up to a radius of ~ 4?. Using the near-infrared VISTA Survey of the Magellanic Clouds, our data cover a thrice larger area compared with previous studies. We identify red giant branch (RGB) stars in spatially distinct Y, (Y - Ks) colour–magnitude diagrams. In any of our selected subregions, the RGB slope is used as an indicator of the average metallicity, based on calibration to metallicity using spectroscopic data. The metallicity distribution across the SMC is unimodal and can be fitted by a Gaussian distribution with a peak at [Fe/H] = -0.97 dex (s[Fe/H] = 0.05 dex). We find evidence of a shallow gradient in metallicity (-0.031 ± 0.005 dex deg-1) from the galactic centre to radii of 2?–2.5?, followed by a flat metallicity trend from ~ 3.5? to 4?. We find that the SMCâs metallicity gradient is radially asymmetric. It is flatter towards the East than to the West, hinting at mixing and/or distortion of the spatial metallicity distribution (within the inner 3?), presumably caused by tidal interactions between the Magellanic Clouds.

Journal Article Type Article
Acceptance Date Jul 15, 2020
Online Publication Date Jul 24, 2020
Publication Date 2020-09
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 497
Issue 3
Pages 3746-3760
DOI https://doi.org/10.1093/mnras/staa2140
Keywords stars: abundances, Hertzsprung-Russell and colour-magnitude diagrams, galaxies: abundanes, Local Group, Magellanic Clouds
Publisher URL https://doi.org/10.1093/mnras/staa2140

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