Exploding source of lithium

by Mary Caperton Morton
Monday, June 1, 2015

Artist's rendering of a nova explosion in a binary star system. Credit: National Astronomical Observatory of Japan.

Trace amounts of lithium are found in all living organisms, and the soft metal is widely used in cellphones and batteries, and as a mood-stabilizing medication. But the galactic source of the element has been unclear.

Scientists have conceived of many possible ways in which lithium could be produced in the universe, including through nucleosynthesis during the Big Bang, inside the cores of aging low-mass stars, and during nova and supernova explosions. Astronomers have also considered the interactions of energetic cosmic rays with interstellar matter. But they haven’t determined which process dominates over the others.

Now, a team from the National Astronomical Observatory of Japan (NAOJ) has caught a culprit in the act, observing a classical nova explosion called Nova Delphini 2013 as it generated large amounts of lithium. The new observation provides the first direct evidence that stellar explosions contribute lithium to the galactic medium, the team, led by Akito Tajitsu of NAOJ, reported in Nature.

Classical novae brighten the sky when explosive nuclear reactions ignite on the surface of white dwarf stars; these extremely high-energy events are thought to be one of the main sources for the production of many elements in the universe. The new observations illustrate that Nova Delphini 2013 produced substantially higher amounts of lithium than predicted by theoretical estimates, suggesting that white dwarfs may be the primary source of lithium in the universe.

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