Polarization of thermal molecular lines in the envelope of IK Tau

Details Polarization of thermal molecular lines in the envelope of IK Tau Polarization of thermal molecular lines in the envelope of IK Tau

2012-03-13

arxiv.org/abs/1203.2922v1

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

5 pages, 4 figures, accepted for publication in A&A Letters

Scientific paper

Molecular line polarization is a unique source of information about the magnetic fields and anisotropies in the circumstellar envelopes of evolved stars. Here we present the first detection of thermal CO(J=2-1) and SiO(J=5-4, v=0) polarization, in the envelope of the asymptotic giant branch star IK Tau. The observed polarization direction does not match predictions for circumstellar envelope polarization induced only by an anisotropic radiation field. Assuming that the polarization is purely due to the Goldreich-Kylafis effect, the linear polarization direction is defined by the magnetic field as even the small Zeeman splitting of CO and SiO dominates the molecular collisional and spontaneous emission rates. The polarization was mapped using the Submillimeter Array (SMA) and is predominantly north-south. There is close agreement between the CO and SiO observations, even though the CO polarization arises in the circumstellar envelope at ~800 AU and the SiO polarization at <250 AU. If the polarization indeed traces the magnetic field, we can thus conclude that it maintains a large-scale structure throughout the circumstellar envelope. We propose that the magnetic field, oriented either east-west or north-south is responsible for the east-west elongation of the CO distribution and asymmetries in the dust envelope. In the future, the Atacama Large Millimeter/submillimeter Array will be able to map the magnetic field using CO polarization for a large number of evolved stars.

Affiliated with

Also associated with

No associations

Rating

Polarization of thermal molecular lines in the envelope of IK Tau does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Polarization of thermal molecular lines in the envelope of IK Tau, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polarization of thermal molecular lines in the envelope of IK Tau will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-714853