A possible solution to the mass-loss problem in M-type AGB stars

TL;DR

This paper investigates the dust-driven wind mechanism in M-type AGB stars, emphasizing the importance of grain size in mass-loss processes, using high-resolution interferometry to constrain dust properties.

Contribution

It presents observational constraints on dust grain sizes in M-type AGB stars, aiding the understanding of mass-loss initiation in these stars.

Findings

Preliminary interferometry results suggest larger dust grains are present.

Modeling indicates grain size influences mass-loss rates.

Observations support the need for detailed dust characterization.

Abstract

Mass loss is a fundamental, observationally well-established feature of AGB stars but many aspects of this process still remain to be understood. To date, self-consistent dynamical models of dust-driven winds reproducing the observed mass-loss rates seem only possible for M-type stars if the grains in the close circumstellar environment grow to larger sizes than previously assumed. In order to study the grain-size distribution where the mass loss is initiated, high-spatial-resolution interferometry observations are necessary. We have observed two M-type stars using the VLTI/MIDI instrument to constrain the dust-grain sizes through modeling the 10-micron silicate feature. Complementary observations are scheduled and we will present preliminary results.