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Mass Distribution in Stellar Structures of Local Dwarfs

Published online by Cambridge University Press:  30 October 2019

Karín Menéndez-Delmestre Open the ORCID record for Karín Menéndez-Delmestre [Opens in a new window] ,
Yasmin Coelho ,
Marco Grossi  and
Kartik Sheth
Karín Menéndez-Delmestre
Affiliation:
Valongo Observatory, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil email: kmd@astro.ufrj.br
Yasmin Coelho
Affiliation:
Valongo Observatory, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil email: kmd@astro.ufrj.br
Marco Grossi
Affiliation:
Valongo Observatory, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil email: kmd@astro.ufrj.br
Kartik Sheth
Affiliation:
NASA Headquarters Washington DC, USA
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Abstract

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We study the distribution of mid-infrared light in stellar structures in a large sample (∽ 400) of low-mass (Mstellar <109 MSun) galaxies. Our sample is selected from the Spitzer Survey of Stellar Structures in Galaxies (S4G), which entails deep imaging of nearby galaxies with the IRAC instrument at 3.6/4.5 μ m. Based on the 2D decomposition of the 3.6μ m images, we find that the majority (∽65%) of galaxies in our sample is well-fit by a single disk profile. The rest of the sample is more adequately fit by a disk and an additional component (e.g., bar, nucleus, bulge, second disk component). Bars are present in ∽11% of the sample, marking a sharp drop in the bar fraction compared to that found for more massive galaxies. The typical contribution of bars to the 3.6 μ m light in dwarfs is ∽1-2%, lower than that found in more massive galaxies. These results bring a number of issues into question: why do low-mass galaxies have such low bar fraction? does the bar instability act differently in low-mass galaxies such that a smaller proportion of stellar mass is typically involved in the bar structure? Is the fact that dwarfs are more dark matter dominated playing a role?

Keywords

galaxies: dwarfgalaxies: structureinfrared: galaxies
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 14 , Symposium S344: Dwarf Galaxies: From the Deep Universe to the Present , August 2018 , pp. 340 - 344
Copyright
© International Astronomical Union 2019 

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