Constraining Models of Classical Nova Outbursts with the Murchison Meteorite

Abstract

Infrared observations of nova light curves reveal that classical novae form grains in the expanding shells, ejected into the interstellar medium as a consequence of a violent outburst. Such grains contain nucleosynthetic fingerprints of the nova explosion. In this paper, we analyse different isotopic signatures expected to be present in nova grains on the basis of detailed hydrodynamic calculations of CO and ONe novae and compare them with recent determinations of presolar nova grains from the Acfer 094 and Murchison meteorites.

Presolar Grains

“…These grains have low 12 C/ 13 C and 14 N/ 15 N ratios (Figure 3), large 30 Si excesses (Figure 4), and high 26 Al/ 27 Al ratios ( Figure 5). All these features are predicted to be produced by explosive hydrogen burning taking place in classical novae (e.g., José and Hernanz, 2007;José et al, 1999José et al, , 2003José et al, , 2004Kovetz and Prialnik, 1997;Starrfield et al, 1998), but the predicted anomalies are much larger than those found in the grains, and the nova ejecta have to be mixed with material of close-to-solar isotopic compositions. A comparison of the data with the models implicates ONe novae with a white dwarf mass of at least 1.25 M as the most likely sources (Amari et al, 2001a;José and Hernanz, 2007).…”

Presolar Graphite: Noble Gases and their Origins

“…Nova ejecta are characterised by low 12 C/ 13 C (0.3-1.8), a large range of 14 N/ 15 N (3-130 for CO novae and 0.3-4 for ONe novae) and high 26 Al/ 27 Al (0.01-0.6) (José & Hernanz, 1998;Starrfield, Gehrz & Truran, 1997;Starrfield et al 1998;José et al 2003). In fact, a few presolar grains of a putative nova origin show low 12 C/ 13 C ratios (4-9) (Amari et al 2001).…”

Beacons in the sky: Classical novae vs. X-ray bursts

“…Hence, 13 N and 18 F are responsible for the predicted prompt γ-ray emission (Hernanz et al, 1999, [33]) at and below 511 keV, whereas 7 Be and 22 Na (Gómez-Gomar et al, 1998, [34]), which decay much later (when the envelope is optically thin), are the sources that power line emission at 478 and 1275 keV, respectively. 26 Al is another important radioactive isotope that can be synthesized during nova outbursts, although only its cumulative emission can be observed because of its slow decay. We will briefly focus on the corresponding nuclear paths leading to the synthesis of the above-mentioned gamma-ray emitters, with special emphasis on the nuclear uncertainties associated with the relevant reaction rates.…”

“…In the 20 Ne-enriched envelopes of ONe novae (José et 26 Al production in novae): according to a recent sensitivity study (Iliadis et al, 2002, [60]) in nova nucleosynthesis, the uncertainty associated with the 25 Mg(p, γ) rates in the domain of nova nucleosynthesis (T = 0.1-0.4 GK) is rather limited (i.e., a factor 0.6-1.8 deviation from the nominal rate). Hence, their impact on nova nucleosynthesis is negligible (cf., less than a factor of ∼ 2 change in the 25,26 …”