Skip to main content
SearchLoginLogin or Signup

⁷Li, 22Na, 26Al, and 31P ejected in Carbon-Oxygen and Oxygen-Neon Classical Nova Outbursts

Presentation #400.05 in the session Multiple Stars Systems and Cataclysmic Variables.

Published onJul 01, 2023
⁷Li, 22Na, 26Al, and 31P ejected in Carbon-Oxygen and Oxygen-Neon Classical Nova Outbursts

Classical Novae (CNe) are semi-detached binary systems which consist of a white dwarf (WD) and a cool star (the secondary) which fills its Roche lobe. Material from the secondary flows through the inner Lagrangian point and ultimately falls onto the surface of the WD. In time, the base of the accreted layer becomes degenerate and a thermonuclear runaway (TNR) occurs on the WD surface. This results in the explosive ejection of up to ∼ 10−4M of material expanding at several 100s to several 1000s of km s−1. We report on simulations in which we accrete only solar matter using NOVA (our 1-D, fully implicit, hydro code) and then switch to a mixed composition once the TNR is ongoing. We use a large nuclear reaction network which both produces the necessary energy generation and allows us to predict the isotopic abundances in the ejected gasses. We find that the amount of accreted material is inversely proportional to the initial 12C abundance (as expected). Thus, accreting just solar matter results in a larger amount of accreted material to fuel the outburst; much larger than in earlier studies where a mixed composition was assumed from the beginning of the simulation. Our most important result is that all the simulations (CO or ONe) eject significantly less mass than accreted and, therefore, the WD is growing in mass toward the Chandrasekhar Limit and could ultimately end as either a Supernova Ia explosion or accretion induced collapse. Our most important isotopic predictions are that CNe produce about 100M of 7Li in the galaxy, about 1 M of 26Al in the galaxy, and ∼ 5 x 103M of 31P in the galaxy (31P is about 104 times Solar in ONe ejecta). In addition, our simulations predict that the flux of 1.275MeV γ-rays from 22Na decays, in an individual CN, event is ∼ 4 × 10−5 cm−2s−1 (for a distance of about 1 kpc). Finally, the observations of CNe events imply about 5 to 6 times more 7Li is produced than predicted. If such a ratio holds for other isotopes, then CNe are extremely important for 26Al production in the galaxy.

No comments here