A latitude-dependent wind model for Mira's cometary head

TL;DR

This paper introduces a 3D simulation of Mira's cometary head, demonstrating that a latitude-dependent, steady wind can produce the observed double bow shock structure without requiring time-dependent wind variations.

Contribution

The study presents a novel 3D numerical model showing that steady, latitude-dependent stellar winds can explain Mira's cometary head structure, including the double bow shock.

Findings

The model reproduces Mira's cometary head with a double bow shock.

A steady, latitude-dependent wind suffices to explain observed structures.

Time-dependent wind variations are not necessary for the observed features.

Abstract

We present a 3D numerical simulation of the recently discovered cometary structure produced as Mira travels through the galactic ISM. In our simulation, we consider that Mira ejects a steady, latitude-dependent wind, which interacts with a homogeneous, streaming environment. The axisymmetry of the problem is broken by the lack of alignment between the direction of the relative motion of the environment and the polar axis of the latitude-dependent wind. With this model, we are able to produce a cometary head with a ``double bow shock'' which agrees well with the structure of the head of Mira's comet. We therefore conclude that a time-dependence in the ejected wind is not required for reproducing the observed double bow shock.