a1 Department of Physics & Astronomy, University of Victoria, PO Box 3055, STN CSC, Victoria, BC, V8W 3P6, Canada. e-mail: arpon@uvic.ca ;
a2 National Research Council of Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7, Canada
a3 Department of Physics and Astronomy, San Jose State University, One Washington Square, San Jose, CA 95192-0106, USA
a4 Space Science and Astrobiology Division, MS 245-3, NASA Ames Research Center, Moffett Field, CA, 94035, USA
(Online publication November 25 2011)