Image type: Technical
© Canada-France-Hawaii
Telescope Corporation 2005
The achromatic polarimeter, featuring rotatable retarders, is
installed at the Cassegrain focus of the telescope. It provides a
measurement of how much the light coming from the observed object is
polarized. Polarization is an excellent tracer of the magnetic field
surrounding the area where the light originates from, or the magnetic
field the light could have encountered on its way to us.
Image type: Technical
© Canada-France-Hawaii Telescope Corporation 2005
From the polarimetric module, the light is sent through optics fibers to a bench-mounted high-resolution spectrograph, yielding full coverage of the 370-1,000 nm wavelength range in a single exposure at a dispersion of R~60000. The polarization of thousands of spectral features can be measured at once:.
High resolution image
Image type: Astronomical
© Casse & Keppens 2004
In the model used in this numerical simualtion, the rotation of the disk twists around the rotation axis the initially vertical magnetic field, which responds by slowing down the plasma in the disk and by causing it to fall towards the central star. The magnetic energy flux produced in this process points away from the disk, pushing the surface plasma outwards, leading to a wind from the disk and sometimes a collimated jet.
The ESPADOnS observations of FU Orionis led to the first detecion ever of such a magnetic field.
View the animation
Image type: Astronomical
©Burrows, STSci/ESA, WFPC2, NASA
This accretion disk is not FU Orionis, but HH30. The jet is seen here in reddish color perpendicular to the accretion disk. The disk itself appears as a dark horizontal line between two bright lobes at the bottom of the image.FU Ori does not exhibit such a jet, despite its magnetic topology being apparently favourable for jet-launching. In the FU Ori system, the observed magnetic plasma is slowed down much more than models expect. This unexpected field property may be a hint as to why FU Ori fails to collimate its wind into a jet, as opposed to a similar object like HH30.
Image type: Technical
©
Canada-France-Hawaii
Telescope Corporation 2005
High resolution version
Image type: Technical
©
Canada-France-Hawaii
Telescope Corporation 2005
High resolution
version
