Dust from evolved stars: a pilot analysis of the AGB to PN transition

TL;DR

This study investigates dust production and evolution during the transition from the asymptotic giant branch (AGB) to planetary nebulae (PN), using spectral analysis and modeling to understand dust formation, destruction, and mass-loss processes.

Contribution

It introduces a novel approach combining stellar evolution and dust formation models to analyze dust in the AGB to PNe transition stages.

Findings

The dust-to-gas ratio in PNe is about 10^-3, lower than expected, indicating possible dust destruction.

Dust formation occurs soon after the AGB tip, with implications for dust survival during stellar evolution.

Spectral energy distribution analysis reveals differences in dust and gas release across evolutionary phases.

Abstract

We present a novel approach to address dust production by low- and intermediate-mass stars. We study the asymptotic giant branch (AGB) phase, during which the formation of dust takes place, from the perspective of post-AGB and planetary nebula (PN) evolutionary stage. Using results from stellar evolution and dust formation modelling, we interpret the spectral energy distribution of carbon-dust-rich sources currently evolving through different evolutionary phases, believed to descend from progenitors of similar mass and chemical composition. Comparing the results of different stages along the AGB to PNe transition, we can provide distinct insights on the amount of dust and gas released during the very late AGB phases. While the post-AGB traces the history of dust production back to the tip of the AGB phase, investigating the PNe is important to reconstruct the mass-loss process experienced after the last thermal pulse. The dust surrounding the post-AGB was formed soon after the tip of the AGB. The PNe dust-to-gas ratio is $\sim10^{-3}$, 2.5 times smaller than what expected for the same initial mass star during the last AGB interpulse, possibly suggesting that dust might be destroyed during the PN phase. Measuring the amount of dust present in the nebula can constrains the capacity of the dust to survive the central star heating.