Yes, of course. After looking at Model Description, I noticed that the galaxy cores are treated as heavy bodies. Therefore, this particular example has 2 heavy bodies and 698 light bodies (stars). You may want to find the position of a heavy body, and find all the stars that satisfy your bounding condition. Check 'heavy1' output from "Apply Gravity" block for cores position.
For box area example, (x1 < box_width < x2) && (y1 < box_height < y2). You can use logical indexing or find() Since you only want your code to execute at the end of the simulation, you may pass a clock input into your function and do:
if clock == end_time % 250 in the example
% find position of core
% find stars in an area around core
end
Hope this helps. Good luck!
