Figure 7: Chart of the nuclides. Indicated are the stable isotopes (black), unstable isotopes which have been found (yellow), and isotopes that are possible to be studied (in dark and light green). The wiggly line at the bottom of the plot is a path of possible element production via the r-process of rapid neutron capture. Not far below this is a "drip line" for nuclei that are unstable to neutron emission, indicating a limit of nuclear existence. There are similar lines for proton-rich nuclei.