New models for the rapid evolution of the central star of the Stingray Nebula

TL;DR

This paper models the rapid evolution of the Stingray Nebula's central star using stellar evolution calculations with Late Thermal Pulse events, explaining its observed rapid changes in brightness and temperature over recent decades.

Contribution

It introduces LTP-based stellar evolution models that account for the rapid evolution and fading of the Stingray Nebula's central star, matching recent observations.

Findings

LTP models explain rapid stellar heating and dimming.

Models account for nebular ionization and mass loss episodes.

Reproduces observed timescales of the star's evolution.

Abstract

We present stellar evolution calculations from the Asymptotic Giant Branch (AGB) to the Planetary Nebula (PN) phase for models of initial mass 1.2 M\odot and 2.0 M\odot that experience a Late Thermal Pulse (LTP), a helium shell flash that occurs following the AGB and causes a rapid looping evolution between the AGB and PN phase. We use these models to make comparisons to the central star of the Stingray Nebula, V839 Ara (SAO 244567). The central star has been observed to be rapidly evolving (heating) over the last 50 to 60 years and rapidly dimming over the past 20 - 30 years. It has been reported to belong to the youngest known planetary nebula, now rapidly fading in brightness. In this paper we show that the observed timescales, sudden dimming, and increasing Log(g), can all be explained by LTP models of a specific variety. We provide a possible explanation for the nebular ionization, the 1980s sudden mass loss episode, the sudden decline in mass loss, and the nebular recombination and fading.