The Impact of Nova Outbursts on the Chemical Abundance of the Interstellar Medium

Nova outbursts are the results of thermonuclear runaways, which occur when sufficient material accretes on the surfaces of white dwarfs (WDs). Using the MESA code, we construct a detailed grid for carbon-oxygen and oxygen-neon-magnesium novae. By employing population synthesis methods, we conduct a statistical analysis of the distribution of novae in the Milky Way. In our models, on average, a typical nova system may undergo about 8000 eruptions and the Galactic nova rate is ∼130 yr −1 . The C, N, and O elements in nova ejecta are strongly affected by the mixing degree between WD core and accreted material. Our results show that the average value of 12 C/ 13 C in nova ejecta is about an order of magnitude lower than that on the surface of a red giant, that for 16 O/ 17 O is about 5 times lower, and that for 14 N/ 15 N is about 1.5 times lower. The annual yields of 13 C , 15 N, and 17 O from nova ejection are larger than those from AGB stars. This indicates that compared to a red giant, nova eruptions are a more important source of the odd-numbered nuclear elements of 13 C , 15 N, and 17 O in the Galactic interstellar medium.