The Imprint of Nova Nucleosynthesis in Presolar Grains

Abstract

Infrared and ultraviolet observations of nova light curves have confirmed grain formation in their expanding shells that are ejected into the interstellar medium by a thermonuclear runaway. In this paper, we present isotopic ratios of intermediate-mass elements up to silicon for the ejecta of CO and ONe novae, based on 20 hydrodynamic models of nova explosions. These theoretical estimates will help to properly identify nova grains in primitive meteorites. In addition, equilibrium condensation calculations are used to predict the types of grains that can be expected in the nova ejecta, providing some hints on the puzzling formation of C-rich dust in O>C environments. These results show that SiC grains can condense in ONe novae, in concert with an inferred (ONe) nova origin for several presolar SiC grains.Comment: 42 pages. Accepted for publication in The Astrophysical Journa

Presolar Grains From Novae: Evidence From Neon and Helium Isotopes in Comet Dust Collections

“…Of the combination of theoretical hydrodynamic calculations and nuclear reaction networks describing element synthesis in stellar environments, only those for total ejecta compositions in neon nova outbursts specifically predict the combination of negligible 3 He, low 4 He/ 20 Ne, high 20 Ne/ 21 Ne, and 20 Ne/ 22 Ne ratios in and above the range of ∼25 to ∼150 (Figure 3) measured in these particles (Starrfield et al 2009;José et al 2004).…”

First measurement of Mg isotope abundances at high redshifts and accurate estimate of Δα/α

“…Tables are only available in electronic form at http://www.aanda.org nuclide (José et al 1999(José et al , 2004, or in outflows from AGB-stars where the so-called hot-bottom burning operates (Karakas et al 2003(Karakas et al , 2006(Karakas et al , 2010. Direct measurements of the Mg isotopic ratio in different objects allow us to identify the sources of the chemical enrichment and thus to understand the chemical evolution of these objects.…”

Absolute determination of theNa22(p,γ)Sallaska1, Wrede2, Garcı́a3 et al. 2011Phys. Rev. C255340View full textAdd to dashboardCite

“…This suggests we are now on the verge of being able to detect this signal. In addition, Ne isotopic ratios in some meteoritic presolar graphite grains imply the in-situ decay of 22 Na produced by nucleosynthesis in novae [13,14] and/or supernovae [15].…”