ALMA Large Program · 2025.1.00383.L

Following the flow of star cluster formation

Panta Rei maps the density structure and velocity field of 259 star-forming clumps, building a consistent view of how gas moves from molecular clouds into forming clusters across four orders of magnitude in scale.

The ALMA program linking the gas dynamics from cloud-scale reservoirs down to protostellar environments.

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Panta Rei project overview — star formation flow from SEDIGISM clouds through ALMA clumps to ALMAGAL cores, spanning scales from 20 pc down to 0.2 pc

Mass-Radius plot of the 259 Herschel ALMAGAL sources (red) and their parent 158 SEDIGISM+OGHReS molecular clouds (green). The blue shaded area shows the scales that will be probed by our Panta Rei program.

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Scientific premise

Clumps appear dynamically decoupled from their parent clouds.

Panta Rei is designed to understand why that decoupling emerges, how matter is funnelled across scales, and what that means for the assembly of stellar populations.

Star formation spans many orders of magnitude in spatial scale and gas density. Within that hierarchy, parsec-scale clumps occupy a pivotal role: they are the direct progenitors of star clusters, yet observations suggest they no longer simply inherit the motions of their surrounding molecular clouds.

By combining a uniform ALMA sample with existing large-scale and small-scale surveys, Panta Rei can test how gas is reorganised, compressed, and transported as the cluster formation process unfolds.

Panta Rei scientific premise — the flow of matter from molecular clouds down to protostellar cores

Research pillars

Three complementary views of the same process

Density structure

Resolve the millimetre continuum of the full clump sample to recover core populations and relate them to the dynamical state of each environment.

Velocity fields

Trace infall, rotation, and converging flows to quantify how efficiently matter is channelled from cloud reservoirs into the dense clump phase.

Multi-scale continuity

Connect new ALMA observations with existing cloud-scale and core-scale datasets to follow a single physical narrative across four orders of magnitude.

Scale ladder

The physical sequence we follow

Molecular cloud tens of pc

Existing large-scale surveys define the parent environment and the reservoir from which stellar clusters form.

Clump ~ 1 pc

The central Panta Rei scale, where the gas appears to decouple dynamically from the natal cloud.

Core ~ 0.1 pc

Fragments that will form single stars or small multiple systems, shaping the stellar mass function.

Protostellar environment ~ 2000 AU

The smallest resolved regime, where accretion onto individual protostars becomes directly visible.

Program scale

A uniform view across the Galactic sample

0 Clumps mapped

0 Maximum sample distance

0 Smallest scale resolved

0 Largest scale mapped

Collaboration

Working with Panta Rei

Collaboration members can consult approved projects, data-management material, practical documents, and shared resources through a unified members area.

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