Isobar

The term isobar is ambiguous and may refer to:

• nuclear isobar: two different nuclear species having the same total number of protons and neutrons, like ${\phantom{A}}_{\phantom{20}}^{\phantom{40}}{\phantom{A}}_{\phantom{2}20}^{\phantom{2}40}\mathrm{C}\mathrm{a}$ and ${\phantom{A}}_{\phantom{19}}^{\phantom{40}}{\phantom{A}}_{\phantom{2}19}^{\phantom{2}40}\mathrm{K}$
• pressure isobar: a thermodynamic process that keeps pressure constant throughout the action