Shock cooling of a red-supergiant supernova at redshift 3 in lensed images

Understand

The core-collapse supernova of a massive star rapidly brightens when a shock, produced following the collapse of its core, reaches the stellar surface.

• As the shock-heated star subsequently expands and cools, its early-time light curve should have a simple dependence on the progenitor's size and therefore final evolutionary state.
• Measurements of the progenitor's radius from early light curves exist for only a small sample of nearby supernovae, and almost all lack constraining ultraviolet observations within a day of explosion.
• The several-day time delays and magnifying ability of galaxy-scale gravitational lenses, however, should provide a powerful tool for measuring the early light curves of distant supernovae, and thereby studying massive stellar populations at high redshift.