V339 Delphini (or Nova Delphini 2013 or V339 Del)
is a classical nova discovered during an eruption in 2013
that peaked at a magnitude of +4.3.
It was the first nova in which signs of lithium synthesis
were found, a process that had been theorized to occur but had
never been detected.
Observed absorption lines were interpreted as those
of beryllium-7, which decays into the
common stable lithium isotope, lithium-7.