# JVLA Observations of IC342: Probing Star Formation in the Nucleus

## TL;DR

This study uses JVLA radio observations to analyze star formation in IC342's nucleus, revealing dense HII regions and estimating star formation rates, providing insights into nuclear star formation in spiral galaxies.

## Contribution

First detailed radio study of IC342's nucleus using multiple frequencies, modeling ionized gas regions and estimating star formation rates with high spatial resolution.

## Key findings

- Identified two spatially and kinematically distinct ionized gas components.
- Modeled ionized regions as dense, compact HII regions, fitting observational data.
- Estimated a star formation rate of approximately 0.15 solar masses per year.

## Abstract

IC342 is a nearby, late-type spiral galaxy with a young nuclear star cluster surrounded by several giant molecular clouds. The IC342 nuclear region is similar to the Milky Way and therefore provides an interesting comparison. We explore star formation in the nucleus using radio recombination line (RRL) and continuum emission at 5, 6.7, 33, and 35 GHz with the JVLA. These radio tracers are largely unaffected by dust and therefore sensitive to all of the thermal emission from the ionized gas produced by early-type stars. We resolve two components in the RRL and continuum emission within the nuclear region that lie east and west of the central star cluster. These components are associated both spatially and kinematically with two giant molecular clouds. We model these regions in two ways: a simple model consisting of uniform gas radiating in spontaneous emission, or as a collection of many compact HII regions in non-LTE. The multiple HII region model provides a better fit to the data and predicts many dense (ne ~ 10^4-10^5 cm-3), compact (< 0.1 pc) HII regions. For the whole nuclear region as defined by RRL emission, we estimate a hydrogen ionizing rate of NL ~ 2 x 10^{52} s^{-1}, corresponding to equivalent ~ 2000 O6 stars and a star formation rate of ~ 0.15 Msun/year. We detect radio continuum emission west of the southern molecular mini spiral arm, consistent with trailing spiral arms.