The Study of 29Si(p,γ)30P and Its Impact on Classical Nova Nucleosynthesis

Classical novae are stellar explosions occurring in binary systems consisting of a white dwarf and a main sequence partner. Thermonuclear runaways, occurring after the accretion of matter from the main sequence star onto the surface of the white dwarf, eject nuclear processed material into the interstellar medium and significantly contribute to the galactic chemical evolution. Novae can be observed spectroscopically as the ejecta shells disperse or isotopically after the matter condenses into presolar stardust grains, which are incorporated into meteors and sometimes arrive on earth many years later. These observables carry signatures of the processes that created them and aid our understanding of classical novae. However, open questions about the effect of reaction rate uncertainty compromise the effective use of these tools and our understanding of novae as a whole. First, nova nucleosynthesis simulations were performed to explore the effect of reaction rate uncertainty on the final abundances of ejected matter. These results, when compared to elemental ratios from spectroscopic observations and the isotopic ratios of presolar grain measurements, revealed the critical importance of several reactions. One of these reactions, 29Si(p,γ)30P, was chosen as the focus of this dissertation. Several resonances in this reaction were investigated at the Laboratory for Experimental Nuclear Astrophysics. A new measurement of the Erlab = 325.79 ± 0.58 keV resonance improved upon the uncertainty of the resonance strength measured by Reinecke et al. (1985) and found that the resonance strength, ωγ = 23 ± 4 meV, was a factor of 1.5 larger than previously thought. The Erlab = 314.36 ± 0.81 keV resonance was observed for the first time, and its strength, ωγ = 100 ± 20 μeV, proved significantly stronger than predicted by theoretical estimates. An experimental resonance strength upper limit comparable to theoretical estimates, ωγ < 3.69 × 10−7 eV, was established for the unobserved Erlab = 221 keV resonance as well. The impact of these measurements was clear upon the reevaluation of the 29Si(p,γ)30P rate. Compared to the recent evaluation of Iliadis et al. (2010c), the new thermonuclear rate shows a factor of 1.5 increase and a twofold reduction to its uncertainty in the Gamow window of classical nova nucleosynthesis.Doctor of Philosoph