A SINFONI view of circum-nuclear star-forming rings in spiral galaxies

TL;DR

This study uses near-infrared integral-field spectroscopy to analyze star formation in circumnuclear rings of spiral galaxies, supporting a model where star formation is triggered at specific resonance points and evolves as clusters rotate.

Contribution

It introduces a robust method to age-date stellar clusters in rings and compares two star formation scenarios, favoring the 'Pearls on a string' model.

Findings

Star formation is likely triggered at the intersection of the bar and Lindblad resonance.

Clusters passively evolve as they rotate around the ring.

The 'Pearls on a string' scenario is favored over stochastic models.

Abstract

We present near-infrared (H- and K-band) SINFONI integral-field observations of the circumnuclear star formation rings in five nearby spiral galaxies. We made use of the relative intensities of different emission lines (i.e. [FeII], HeI, Brg) to age date the stellar clusters present along the rings. This qualitative, yet robust, method allows us to discriminate between two distinct scenarios that describe how star formation progresses along the rings. Our findings favour a model where star formation is triggered predominantly at the intersection between the bar major axis and the inner Lindblad resonance and then passively evolves as the clusters rotate around the ring ('Pearls on a string' scenario), although models of stochastically distributed star formation ('Popcorn' model) cannot be completely ruled out.