ALMA Reveals Potential Localized Dust Enrichment from Massive Star Clusters in II Zw 40

TL;DR

This study uses high-resolution submillimeter imaging to investigate star formation and dust enrichment in the galaxy II Zw 40, revealing localized dust enhancement likely due to massive star clusters.

Contribution

It provides the first detailed subarcsecond observations linking dust, gas, and star formation at cloud scales in a starburst galaxy, highlighting localized dust enrichment.

Findings

Dust contributes about a third of the 870μm emission.

Dust continuum is enhanced near star-forming regions.

Gas-to-dust ratio appears low and variable in the starburst region.

Abstract

We present subarcsecond images of submillimeter CO and continuum emission from a local galaxy forming massive star clusters: the blue compact dwarf galaxy II Zw 40. At $\sim$0.4" resolution (20 pc), the CO(3-2), CO(1-0), 3mm and 870${\mu}$m continuum maps illustrate star formation on the scales of individual molecular clouds. Dust contributes about a third of the 870${\mu}$m continuum emission, with free-free accounting for the rest. On these scales, there is not a good correspondence between gas, dust, and free-free emission. Dust continuum is enhanced toward the star-forming region as compared to the CO emission. We suggest that an unexpectedly low and spatially variable gas-to-dust ratio is the result of massive clusters of the starburst.