The kinematic characteristics of magnetic O-type stars

TL;DR

This study investigates the kinematic properties of magnetic O-type stars to explore their potential status as runaway stars, providing insights into the origins of their magnetic fields.

Contribution

It analyzes the space velocities of seven magnetic O-type stars to assess their runaway status, linking kinematics with magnetic field origins.

Findings

Five out of seven stars are candidate runaway stars.

Two stars are likely members of known clusters.

HD164794's magnetic field likely has a different origin due to binarity.

Abstract

Although magnetic fields have been discovered in ten massive O-type stars during the last years, the origin of their magnetic fields remains unknown. Among the magnetic O-type stars, two stars, HD36879 and HD57682, were identified as candidate runaway stars in the past, and theta^1 Ori C was reported to move rapidly away from its host cluster. We search for an explanation for the occurrence of magnetic fields in O-type stars by examining the assumption of their runaway status. We use the currently best available astrometric, spectroscopic, and photometric data to calculate the kinematical status of seven magnetic O-type stars with previously unknown space velocities. The results of the calculations of space velocities suggest that five out of the seven magnetic O-type stars can be considered as candidate runaway stars. Only two stars, HD155806 and HD164794, with the lowest space velocities, are likely members of Sco OB4 and NGC6530, respectively. However, the non-thermal radio emitter HD164794 is a binary system with colliding winds, for which the detected magnetic field has probably a different origin in comparison to other magnetic O-type stars.