Lithium find in exploding star could help solve astronomy puzzle

SANTIAGO – Astronomers have discovered lithium in a type of stellar explosion known as a nova for the first time, a find that helps clear up a longstanding mystery in astrophysics about the quantity of the element that has been observed in stars.

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CrazyNeutrino said:

Lithium find in exploding star could help solve astronomy puzzle

SANTIAGO – Astronomers have discovered lithium in a type of stellar explosion known as a nova for the first time, a find that helps clear up a longstanding mystery in astrophysics about the quantity of the element that has been observed in stars.

More…

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Older stars do not have as much lithium as the models suggest, while younger ones have more. Astronomers have long speculated that the latter part of the problem could be explained by novae expelling the element, “seeding” space with lithium and enriching the interstellar medium from which new stars are born. But no clear evidence to date has been found of lithium in novae.

That’s actually the opposite of my understanding. I thought that older stars have more lithium than the mathematical models suggest. That’s because nuclear reactions within stars rapidly destroy all lithium that reaches the core, and convection in the star’s outer layers takes surface lithium down to the core. So stars lose lithium from their surface as they age. But some observations had shown that older stars can have lithium on the surface, from memory it was concluded that this lithium was created by a sputtering effect of high energy particles, in much the same way that the Ozone Layer is created in Earth’s stratosphere.

Novas/novae are generally the result of explosions on the surface of white dwarf stars. As a result, what you see reflects what the atmosphere of the white dwarf is, which can vary enormously. eg. https://en.wikipedia.org/wiki/White_dwarf#Atmosphere_and_spectra
But the atmosphere would seldom contain lithium.

This leads to three possibilities. One is that the observed lithium comes from the outer surface of a white dwarf formed from a young (and hence lithium rich) main sequence star brighter than the Sun. The second is that the observed lithium comes from a planetary nebula around the white dwarf. The third is that lithium was generated in the rapid hydrogen+helium fusion in the nova explosion itself and then got frozen out by the sudden decrease in temperature before it could be destroyed.

Checking paper.
“We have detected an absorption feature at 6695.6 \AA\, that we have identified as blue—shifted 7Li I λ6708 \AA. The absorption line, moving at -550 km/s”.

That’s absorption not emission, and 550 km/s which is fast.