\section{New Nature Astronomy paper}

In a recent paper in Nature Astronomy (\url{https://www.nature.com/articles/s41550-023-01975-1}),
J\"orn Warnecke, Maarit J. Korpi-Lagg, Matthias Rheinhardt, and Fred Gent
reported on {\sc Pencil Code} runs with a resolution of $4096^3$ mesh points.
This allowed the authors to reach Reynolds numbers, $\Rey=\urms/\nu\kf$,
of up to 33,000 and magnetic Prandtl numbers ($\Pm$) down to 0.0025.
This high resolution is indeed needed to answer the question,
whether a small-scale dynamo (SSD) is possible at extremely  low $\Pm$ as 
present in the Sun or stars.
%The authors found that contrary to earlier findings the SSD not only turns
%AB: omit
The authors found that the SSD not only turns
out to be possible for $\Pm$ down to 0.0031 but also becomes increasingly
easier to excite for $\Pm$ below about 0.05, see \Fig{plambda_NatAst}.
This behavior was related to the known hydrodynamic phenomenon 
%MR:
%referred to as 
called 
the bottleneck
effect. Extrapolating our results to solar values of PrM indicates   %MR: give the value?
that an SSD would be possible under such conditions. This study is
currently extended to even higher resolutions using the GPU code
%Astaroth, achieving speed-ups of 20-60 versus Pencil code. This
Astaroth, achieving speed-ups of 20--60 compared to the {\sc Pencil code}.
%This solver enables us to determine not only the critical magnetic Reynolds
%AB: them
This solver enables them to determine not only the critical magnetic Reynolds
%number, but also the saturation field strengths at low $\Pm$.
%AB: refer here to picture
number, but also the saturation field strengths at low $\Pm$;
see \Fig{cover_NatAst} for an illustration of the magnetic field.

The paper was highlighted by Steven Tobias in a Nature Astronomy news
\& view item \url{https://www.nature.com/articles/s41550-023-01971-5}
and even in the New York Times
\url{https://www.nytimes.com/interactive/2023/06/20/science/summer-solstice-sun.html}.

\begin{figure*}[h]\begin{center}
\includegraphics[width=.80\textwidth]{cover_NatAst}
\end{center}\caption[]{
Visualization of the magnetic field in a logarithmic scale for
simulation with 4096$^3$ mesh points, $\Rey$=33.000 and $\Pm$=0.005.
}\label{cover_NatAst}\end{figure*}