Herschel's view into Mira's head

TL;DR

Herschel's observations of Mira Ceti reveal complex, broken arc structures in the infrared environment shaped by interactions between the star's wind, its companion, and the interstellar medium, challenging previous expectations.

Contribution

This study provides detailed Herschel PACS imaging of Mira's environment, uncovering complex arc structures and their disruption by outflows, offering new insights into stellar wind-ISM interactions.

Findings

Broken arcs stretch over 80-100 degrees.

IR arcs are disrupted by fast outflows.

Arcs are located 550-8000 AU from Mira.

Abstract

Herschel's PACS instrument observed the environment of the binary system Mira Ceti in the 70 and 160 micron bands. These images reveal bright structures shaped as five broken arcs and fainter filaments in the ejected material of Mira's primary star. The overall shape of the IR emission around Mira deviates significantly from the expected alignment with Mira's exceptionally high space velocity. The observed broken arcs are neither connected to each other nor are they of a circular shape; they stretch over angular ranges of 80 to 100 degrees. By comparing Herschel and GALEX data, we found evidence for the disruption of the IR arcs by the fast outflow visible in both Halpha and the far UV. Radial intensity profiles are derived, which place the arcs at distances of 6-85" (550 - 8000 AU) from the binary. Mira's IR environment appears to be shaped by the complex interaction of Mira's wind with its companion, the bipolar jet, and the ISM.