Novae Ejecta as Discrete Adiabatically Expanding Globules

TL;DR

This paper proposes a model explaining the spectral evolution of novae through ejected dense globules and a surrounding envelope, accounting for observed ionization differences and spectral types.

Contribution

It introduces a novel model of nova ejecta as discrete adiabatically expanding globules combined with a circumbinary envelope, explaining spectral and ionization variations.

Findings

The model accounts for the correlation between X-ray and visible spectra in novae.

It explains the coexistence of different ionization states in nova ejecta.

The model predicts spectral type dominance based on mass loss rates.

Abstract

Available data for novae show that the X-ray and visible spectral regions correlate with each other as they evolve. Large differences in ionization exist simultaneously in the two wavelength regimes, and a straightforward model is proposed that explains the characteristics observed in both spectral regimes. Its key features are (1) ejected blobs of very high density gas from the white dwarf that expand to create within each clump a wide range of emitting density, ionization, and velocity, and (2) a more homogeneous circumbinary envelope of gas that is produced by secondary star mass loss. The relative mass loss rates from the two stars determine whether the He/N or the Fe II visible spectrum predominates during decline, when hard X-rays are detected, and when the white dwarf can be detected as a super soft X-ray source.