A lanthanide-rich kilonova in the aftermath of a long gamma-ray burst

Understand

Kilonovae are a rare class of astrophysical transients powered by the radioactive decay of nuclei heavier than iron, synthesized in the merger of two compact objects.

• Over the first few days, the kilonova evolution is dominated by a large number of radioactive isotopes contributing to the heating rate.
• On timescales of weeks to months, its behavior is predicted to differ depending on the ejecta composition and merger remnant.
• However, late-time observations of known kilonovae are either missing or limited.