Non-Radial Pulsations in Post-Outburst Novae

TL;DR

This paper models non-radial g-mode oscillations in post-outburst novae, linking theoretical predictions with observed X-ray oscillations, and finds that the excited modes have shorter periods than observed.

Contribution

It presents the first models of unstable surface g-modes in novae that match observed oscillation periods, advancing understanding of nova pulsations.

Findings

Models exhibit unstable surface g-modes with periods similar to observed oscillations.

Excited mode periods are shorter than those observed in novae.

Provides insight into the internal dynamics of post-outburst novae.

Abstract

After an optical peak, a classical or recurrent nova settles into a brief (days to years) period of quasi-stable thermonuclear burning in a compact configuration nearly at the white dwarf (WD) radius. During this time, the underlying WD becomes visible as a strong emitter of supersoft X-rays. Observations during this phase have revealed oscillations in the X-ray emission with periods on the order of tens of seconds. A proposed explanation for the source of these oscillations are internal gravity waves excited by nuclear reactions at the base of the hydrogen-burning layer. In this work, we present the first models exhibiting unstable surface $g$-modes with periods similar to oscillation periods found in galactic novae. However, when comparing mode periods of our models to the observed oscillations of several novae, we find that the modes which are excited have periods shorter than that observed.