Relationships between the stellar, gaseous, and star formation disks in LITTLE THINGS dwarf irregular galaxies: Indirect evidence for substantial fractions of dark molecular gas

The stellar, gaseous and young stellar disks in the LITTLE THINGS sample of nearby dwarf irregular galaxies are fitted with functions to search for correlations between the parameters. We find that the H I radial profiles are generally flatter in the center and fall faster in the outer regions than the V-band profiles, while young stars are more centrally concentrated, especially if the H I is more centrally flat. This pattern suggests that the H I is turning into molecules in the center, and the molecular clouds are forming stars and FUV. A model that assumes the molecular surface density is proportional to the total gas surface density to a power of 1.5 or 2, in analogy with the Kennicutt- Schmidt relation, reproduces the relationship between the ratio of the visible to the H I scale length and the H I Sérsic index. The molecular fraction is estimated as a function of radius for each galaxy by converting the FUV to a molecular surface density using conventional calibrations. The average molecular fraction inside 3RD is 23% ± 17%. However, the break in the stellar surface brightness profile has no unified tracer related to star formation.

This is the Accepted Manuscript version of an article accepted for publication in [Astronomical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.3847/1538-3881/abd089.

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Work Title Relationships between the stellar, gaseous, and star formation disks in LITTLE THINGS dwarf irregular galaxies: Indirect evidence for substantial fractions of dark molecular gas
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Open Access
Creators
  1. Deidre A. Hunter
  2. Bruce G. Elmegreen
  3. Esther Goldberger
  4. Hannah Taylor
  5. Anton I. Ermakov
  6. Kimberly A. Herrmann
  7. Se Heon Oh
  8. Bradley Malko
  9. Brian Barandi
  10. Ryan Jundt
License In Copyright (Rights Reserved)
Work Type Article
Publisher
  1. Astronomical Journal
Publication Date January 18, 2021
Publisher Identifier (DOI)
  1. https://doi.org/10.3847/1538-3881/abd089
Deposited January 06, 2025

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Version 1
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  • Created
  • Added 2012.00146-1.pdf
  • Added Creator Deidre A. Hunter
  • Added Creator Bruce G. Elmegreen
  • Added Creator Esther Goldberger
  • Added Creator Hannah Taylor
  • Added Creator Anton I. Ermakov
  • Added Creator Kimberly A. Herrmann
  • Added Creator Se Heon Oh
  • Added Creator Bradley Malko
  • Added Creator Brian Barandi
  • Added Creator Ryan Jundt
  • Published
  • Updated