Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/HOUDE%20Colloquium.pdf
Western University
DEPARTMENT OF PHYSICS AND ASTRONOMY
PHYSICS & ASTRONOMY COLLOQUIUM
Date: Thursday, 24th May 2012
Time: 1:30 p.m.
Location: Physics & Astronomy Seminar Room 22
Dr. Martin Houde
Department of Physics & Astronomy
Western University
“Non-Zeeman Circular Polarization Measurements of Astronomical Molecular Lines”
ABSTRACT
I will discuss unexpected results recently obtained with the Four-Stokes-Parameter Spectral Line Polarimeter (FSPPol), developed here at Western, on the polarization properties of rotational molecular lines. I will explain why, although small amounts of linear polarization are expected to be present in their spectral profiles, it is usually ascertained that no circular polarization signals could be detected in rotational transitions of Zeeman insensitive molecules like carbon monoxide (CO). Our recent circular polarization observations of the (J = 2 à 1) rotational transition of CO with FSPPol clearly show that this belief was unfounded. I will present a physical model that seeks to explain these observations, and discuss its implications for the characterization of magnetic fields in molecular clouds.