Stellar Mystery Solved: Exploding Star is a Lithium Factory

Lithium has been detected in stellar material blasting away from an exploding star, possibly revealing the source of the basic element in young stars, thereby solving a mystery that has perplexed astronomers for decades.

The event, known as a nova, occurred in southern skies in December 2013 near the bright star Beta Centauri. A nova is thought to occur in binary star systems where a white dwarf star pulls hydrogen from its binary partner. Once this material reaches a critical mass, the hydrogen undergoes a runaway fusion reaction, causing the white dwarf to erupt.

It has long been known that novae can produce an array of different chemical elements that enrich the interstellar medium with gases that go on to help form later generations of stars. However, though lithium is theorized to also be produced by these explosions, astronomers have not been able to detect any trace of the element in previous novae.

Lithium is one of the few elements that is thought to have been produced by the Big Bang, nearly 14 billion years ago. However, astronomers have observed a greater abundance of lithium in younger stars than older stars, indicating there must be another production mechanism in the modern universe.

So, in the 1970s, astronomers’ attention shifted to novae as being the culprit. Although rare, and much less powerful than their larger supernova cousins, it was thought that over the history of the Milky Way enough novae likely occurred to explain this abundance of lithium. But observations of novae seeking elusive lithium proved fruitless.

Then Nova Centauri 2013 (also known as V1369 Centauri) lit up our skies, an explosion that was easily visible to the naked eye and the brightest nova so far this century.

As reported in a new study published Wednesday in the Astrophysical Journal Letters, Luca Izzo, from Sapienza University of Rome and ICRANet, Pescara, Italy, and his team used the FEROS instrument on the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile, and the PUCHEROS spectrograph on the ESO 0.5-meter telescope at the Observatory of the Pontificia Universidad Catolica de Chile near Santiago, to zoom in on V1369 Centauri.

These new data have revealed a “very clear signature” of lithium speeding away from the stellar explosion at a speed of 2 million kilometers (1.2 million miles) per hour, the first time lithium has ever been seen being produced by a nova.

Read more at Discovery News