Here you can see for example the trace of a helium core.

Links
- https://www.physik-astro.uni-bonn.de/en/news/prof-klaus-desch-macht-den-auftakt-zu-der-kinderuni-im-sommersemester-2024/uni-vl-kinderuniw-150424-135.jpg/image_view_fullscreen
- https://www.physik-astro.uni-bonn.de/en/news/prof-klaus-desch-macht-den-auftakt-zu-der-kinderuni-im-sommersemester-2024/uni-vl-kinderuniw-150424-135.jpg/@@download/image/uni-vl-KinderuniW-150424-135.jpg