Interferometric imaging diagnostics of X Hya's circumstellar environment

TL;DR

This paper uses optical interferometry to image and analyze the close environment of the Mira star X Hya, revealing shape evolution and asymmetries that challenge existing pulsation models.

Contribution

It provides two-epoch interferometric images of X Hya, demonstrating how size variation with wavelength informs stellar atmosphere models and reveals structural changes.

Findings

Angular size varies with wavelength, challenging pulsation models.

Reconstructed images show evolution of shape and asymmetries.

Interferometry enables direct imaging of stellar surfaces.

Abstract

Optical interferometry is a powerful tool to investigate the close environment of AGB stars. With a spatial resolution of a few milli-arcseconds, it is even possible to image directly the surface of angularly large objects. This is of special interest forMira stars and red supergiants for which the dust-wind is initiated from or very close to the photosphere by an interplay between pulsation and convection. Based on two-epoch interferometric observations of the Mira star X Hya, we present how the variation of the angular size with wavelength challenges pulsation models and how reconstructed images can reveal the evolution of the object shape and of its asymmetric structures.