Probing Star-Forming Properties via ALMA Observations of Massive Protocluster IRAS 15596-5301

TL;DR

This study uses ALMA observations to analyze a massive protocluster, revealing filament collisions that likely trigger or accelerate star formation, and identifying dense cores with varying chemical properties.

Contribution

It provides new evidence that filament collisions can trigger star formation, supported by high-resolution ALMA data and detailed molecular line analysis.

Findings

Identified 34 dense cores, including 3 hot molecular cores.

Detected two velocity components and filament collision region.

Clusters in collision regions host more evolved dense cores.

Abstract

To deepen our understanding of star-forming properties, we studied a massive protocluster IRAS 15596-5301 using ALMA 870 um and 3 mm data. High-resolution 870 um data reveal 34 dense cores, including 3 hot molecular cores, with subsequent line surveys detecting 22 molecular species toward them. Two velocity components (I15596-red/I15596-blue) were found in the averaged H13CO+(1-0) spectrum, and two filaments were identified from velocity-resolved integrated intensity maps. A spatial overlap between the two filaments was observed, and this overlapping region exhibits a distinct bridge-shaped feature in the position-velocity diagram constructed along the entire filamentary structures. Combined with the reduced H13CO+/HCO+ ratio in the overlapping region and the three-dimensional position-position-velocity cube data, we conclude that a non-head-on collision occurs between the edges of the two filamentary structures in IRAS 15596-5301. Cluster analysis demonstrates that clusters located in the collision region host more evolved chemical rich dense cores than their counterparts in other regions. Our results thus indicate that star formation in I15596 is triggered or accelerated by a mild non-head-on collision between two filaments.