(Proposal ID) S16B-073

(PI) Arai, Akira

(Proposal Title)
Nucleosynthesis in Thermonuclear Runaway of Classical Novae

(Abstract)
Classical nova explosions are a consequence of the unstable ignition of 
hydrogen in accreted envelopes on white dwarfs (WDs) in close binary systems. 
Peak temperatures in the range of ~2.0 - 3.5 x 10^{8} K achieved in the 
ensuing thermonuclear runaway (TNR) yield burning of hydrogen to helium, 
fundamentally. During this process, subsequent nuclear reactions are expected 
to produce peculiar isotopic abundances differed from the resultant of the 
nucleosynthesis in stellar interiors or supernovae. Among such isotopes 
produced in TNR, lithium-7 (^{7}Li) and nitrogen-15 (^{15}N) are the most 
remarkable ones. By our recent discovery of the explosive ^{7}Li production in 
three classical novae, novae are now regarded as major ^{7}Li suppliers in the 
current Galaxy. In contrast, there are no strong candidates for ^{15}N 
suppliers except for classical novae. Recently, we have reported the 
possibility of ^{15}N overabundance by measuring the molecular CN bands in the 
post-maximum spectrum of V2627 Oph. In this proposal, we propose to measure 
abundances of ^{7}Li and ^{15}N in post-outburst nova spectra by "Target-of-
Opportunity" observations with Subaru/HDS, to understand the complicate 
nucleosynthesis in TNR, and to evaluate its contribution to the Galactic 
chemical evolution.