Coordinated AMBER and MIDI observations of the Mira variable RR Aql

TL;DR

This study combines near- and mid-infrared interferometry to analyze the pulsating atmosphere and circumstellar environment of the Mira variable RR Aql, providing observational data and model comparisons over multiple pulsation cycles.

Contribution

It presents coordinated VLTI/AMBER and MIDI observations of RR Aql, including multiple epochs, and compares observational data with dynamic model atmospheres to understand stellar pulsation and mass loss.

Findings

Best-fit photospheric angular diameter at phase 2.82 is 9.9 +/- 2.4 mas.

Multiple epochs cover four pulsation cycles, capturing variability.

Comparison with models helps constrain atmospheric structure.

Abstract

We have used near- and mid-infrared interferometry to investigate the pulsating atmosphere and the circumstellar environment of the Mira variable RR Aql. Observations were taken with the VLTI/AMBER (near infrared) and the VLTI/MIDI (mid infrared) instruments. We have obtained a total of 15 MIDI epochs between Apr 9, 2004 and Jul 28, 2007 covering 4 pulsation cycles and one AMBER epoch on Sep 9, 2006 at phase 2.82. This work is also part of an ongoing project of joint VLTI and VLBA observations to study the connection between stellar pulsation and the mass loss process. Here we present a comparison of the AMBER visibility data to a simple uniform disk model as well as to predictions by recent self-excited dynamic model atmospheres. The best fitting photospheric angular diameter of the model atmosphere at phase 2.82 is 9.9 +/- 2.4 mas.