DOI: 10.17617/3.bpwnbo
title: Stellar-wind feedback and magnetic fields around young compact star clusters: 3D magnetohydrodynamics simulations

description: &lt;p&gt;
 3D MHD datasets from
 &lt;a href="https://doi.org/10.1051/0004-6361/202554057"&gt;
 https://doi.org/10.1051/0004-6361/202554057
 &lt;/a&gt;.
 The datasets contain the final time-step (390 kyr) for clusters I, I (high B),
 I (low B), and III (see Tab. 1 in the publication).
 The data was generated with the open-source MHD code PLUTO
 (&lt;a href="https://plutocode.ph.unito.it/"&gt;
 https://plutocode.ph.unito.it/
 &lt;/a&gt;)
 and is in the &lt;code&gt;dbl.h5&lt;/code&gt; format.
 For the format specification and visualisation options, see
 &lt;a href="https://plutocode.ph.unito.it/userguide.pdf"&gt;
 https://plutocode.ph.unito.it/userguide.pdf
 &lt;/a&gt;,
 Ch. 12.
PyPLUTO is recommended for data processing, see &lt;a href="https://pypluto.readthedocs.io/en/stable/"&gt;
 https://pypluto.readthedocs.io/en/stable/
 &lt;/a&gt;.
&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Abstract of the related publication:&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;
 &lt;strong&gt;Context.&lt;/strong&gt;
 The environments of young star clusters are shaped by the interactions of the
 powerful winds of massive stars and their feedback on the cluster birth cloud.
 Several young star clusters show diffuse γ-ray emission on the degree scale,
 which hints at ongoing particle acceleration.
&lt;/p&gt;

&lt;p&gt;
 &lt;strong&gt;Aims.&lt;/strong&gt;
 To date, particle acceleration and transport in star-cluster environments are
 not well understood. A characterisation of magnetic fields and flow structures
 is necessary to progress towards physical models. Previous work has largely
 focused on 100 pc scale feedback or detailed modelling of wind interaction of
 just a few stars. We aim to bridge this gap. We focus in particular on compact
 clusters in order to study collective effects arising from stellar-wind
 interaction. Objects in this class include Westerlund 1 and R136.
&lt;/p&gt;

&lt;p&gt;
 &lt;strong&gt;Methods.&lt;/strong&gt;
 We performed 3D ideal-magnetohydrodynamics simulations of compact young massive
 star clusters. We kinetically injected stellar winds for 46 individual very
 massive stars (M &gt; 40 M⊙) distributed in a spherical region of radius ≤ 1 pc.
 We included a sub-population of five magnetic stars with increased dipole field
 strengths of 0.1–1 kG, and we studied the evolving superbubble over several
 hundred thousand years.
&lt;/p&gt;

&lt;p&gt;
 &lt;strong&gt;Results.&lt;/strong&gt;
 The bulk flow and magnetic fields show an intricate non-uniform morphology that
 is critically impacted by the relative position of individual stars. The
 cluster wind terminates in a strong shock that is non-spherical, and similar to
 the flow, it has non-uniform properties. The magnetic field is composed of both
 highly tangled sections and coherent quasi-radial field-line bundles. Steep
 particle spectra in the teraelectronvolt domain arise naturally from the
 variation of magnetic field magnitude over the cluster-wind termination shock.
 This finding is consistent with γ-ray observations. We deem the scenario of
 petaelectronvolt particle acceleration as unlikely.
&lt;/p&gt;