A magnetically collimated jet from the evolved star W43A
Abstract
We present the first direct measurements of the magnetic field strength and direction in a collimated jet from an evolved star on its way to become a planetary nebula. Very Long Baseline Array (VLBA) observations of the linear and circular polarization of the water masers in the collimated jet of W43A reveal a strong toroidal magnetic field, indicating that the jet is magnetically collimated. The magnetic field strength in the jet extrapolated back to the stellar surface yields a surface field of several Gauss, consistent with the measurements of maser polarization in a large sample of evolved stars. The origin of the magnetic field is yet unknown, although the jet precession might point to the existence of a heavy planet or stellar companion. This is the first direct observational evidence for magnetic collimation in the jets, that likely play an important role in shaping planetary nebulae.
Keywords
Cite
@article{arxiv.astro-ph/0605092,
title = {A magnetically collimated jet from the evolved star W43A},
author = {W. H. T. Vlemmings and P. J. Diamond and H. Imai},
journal= {arXiv preprint arXiv:astro-ph/0605092},
year = {2009}
}
Comments
4 pages, two figures. To appear in the proceedings of IAU Symp. 234, ``Planetary Nebulae in our Galaxy and Beyond.''