Letter to the Editor

Herschel’s view into Mira’s head^⋆

A. Mayer¹, A. Jorissen², F. Kerschbaum¹, S. Mohamed³, S. Van Eck², R. Ottensamer¹, J. A. D. L. Blommaert⁴, L. Decin⁴, M. A. T. Groenewegen⁵, Th. Posch¹, B. Vandenbussche⁴ and Ch. Waelkens⁴

¹ University of Vienna, Department of Astronomy, Türkenschanzstraße 17, 1180 Wien, Austria
e-mail: a.mayer@univie.ac.at
² Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles, CP 226, Boulevard du Triomphe, 1050 Brussels, Belgium
³ Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁴ Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan, 200D, 3001 Leuven, Belgium
⁵ Koninklijke Sterrenwacht van België, Ringlaan 3, 1180 Brussels, Belgium

Received: 6 May 2011
Accepted: 26 May 2011

Abstract

Herschel’s PACS instrument observed the environment of the binary system Mira Ceti in the 70 and 160 μm bands. These images reveal bright structures shaped as five broken arcs and fainter filaments in the ejected material of Mira’s primary star, the famous AGB star o Ceti. 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 Hα 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.