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

Deidre A. Hunter, Bruce G. Elmegreen, Esther Goldberger, Hannah Taylor, Anton I. Ermakov, Kimberly A. Herrmann, Se Heon Oh, Bradley Malko, Brian Barandi, Ryan Jundt

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish (US)
Article numberabd089
JournalAstronomical Journal
Volume161
Issue number2
DOIs
StatePublished - Feb 1 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint

Dive into the research topics of 'Relationships between the stellar, gaseous, and star formation disks in LITTLE THINGS dwarf irregular galaxies: Indirect evidence for substantial fractions of dark molecular gas'. Together they form a unique fingerprint.

Cite this