# Do supernovae produce an appreciable amount of lithium?

David Z's answer to this question got me wondering - is any appreciable amount of lithium produced as the result of a supernova explosion, either by fusion (which seems unlikely to me, but I don't have great intuition for this), or by the decay of unstable species produced by the supernova? If so, what decay chains end with lithium?

• An interesting corollary would be whether or not supernovae can produce high enough temperatures such that lithium will be transmuted to helium, thereby depleting any prior amounts. – HDE 226868 Aug 5 '15 at 22:27

## 1 Answer

Lithium and other light elements (e.g. beryllium) can be formed indirectly from supernovae via cosmic ray spallation, a process where protons and neutrons are ejected when a cosmic ray collides with another atom. The nuclei can then become new elements. Nakamura & Shigeyama (2004) were able to calculate yields for 6Li, 7Li, and isotopes of Beryllium and boron from supernovae SN 1998bw, SN 2002ap, and SN 1994I. The total yield of 6Li and 7Li from each of the supernovae were 5.67$\times$10-7 M$_{\odot}$, 0.1981$\times$10-7 M$_{\odot}$, and 0.0130$\times$10-7 M$_{\odot}$, respectfully.

More specifically, the formula for indirect yield (rather, change in the number of the element over the change in time) is $$\frac{dN_l}{dt}=n_j\int_{\epsilon_{\text{Min}}}^{\epsilon_{\text{max}}}\sigma^l_{i,j}\frac{F_i(\epsilon,t)}{A_im_p}v_i(\epsilon)d\epsilon$$ via the $i+j\to l+\cdots$ reaction, where $n_j$ is number density, $\sigma^l_{i,j}$ is the reaction cross-section, and $A_i$ is the mass number. $F_i(t,\epsilon)$ is a transfer equation.

Much earlier, Truran (1973) cited Meneguzzi et al. (1971) in stating that galactic cosmic ray spallation can account for only 10% of the 7Li abundance, based on measurements in the Solar System. It is thought that supernovae were an important source of these, but they are but no means the only one. More recent estimates (e.g. Prantzos (2010)) set the upper bound at 30% (courtesy of Rob Jeffries).

• So "only" 10% of the lithium around the solar system was caused by high-energy particles slamming into stuff and causing nuclear fusion? – Emilio Pisanty Aug 5 '15 at 21:42
• @EmilioPisanty In theory, yes. I should have clarified that supernovae are not the only source of cosmic rays causing spallation, though. – HDE 226868 Aug 5 '15 at 21:43
• If you're editing, a few quick words on what spallation is wouldn't come amiss. I hadn't heard of it and I'm very, very surprised. – Emilio Pisanty Aug 5 '15 at 21:44
• More recent work suggests that <30% of the solar system Li arises from spallation or primordial nucleosynthesis (Prantzos 2010) arxiv.org/pdf/1203.5662v2.pdf The majority must come from low-mass AGB stars or novae. – ProfRob Aug 5 '15 at 22:04
• @KyleOman I'm not aware of any that arise from supernovae, but my knowledge of nuclear physics is far from extensive. <sup>6</sup>He can decay to <sup>6</sup>Li, and <sup>8</sup>He can decay to <sup>7</sup>Li and <sup>8</sup>Li (the latter being unstable), but I don't think that those could be spurred on by supernovae. – HDE 226868 Aug 15 '15 at 21:41