(Proposal ID) S15B-154

(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 in close binary systems. In 
the early phase of an explosion, the 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 (^7Li) and nitrogen-15 (^{15}N) are 
the most remarkable ones. By our first discovery of the explosive ^7Li 
production in the classical nova V339~Del, novae are now regarded as major 
^7Li suppliers in the current Galaxy. On the other hand, 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 ^7Li and ^15N 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.