International Stellar Polarimetry Meeting Honors Long Tradition at UW

Jun 27, 2011

A group of 75 astronomers from around the world attended the “Stellar Polarimetry: From Birth to Death” meeting at UW-Madison from June 27-30.

This was the first meeting to draw together polarization experts working in all areas of stellar astronomy, hot stars, cool stars, young stars, old evolved stars, and those that have already exploded as supernovae. UW is world-renowned for past and present research using polarization to probe the physics of stars and the interstellar medium, and the meeting was organized mostly by PhD alumni and former department post-doctoral fellows, many of whom have become leaders in the field.

The meeting drew together researchers, both observers and theorists, to share advances in polarimetric methods and applications to stellar sources. It introduced to a wider stellar astronomy community new techniques such as X-ray polarization to be measured with upcoming NASA satellites, and new findings on the structure of supernovae ejecta. The meeting was especially timely, since during it the spectropolarimeter for the SALT telescope, built at UW under the leadership of Professor Ken Nordsieck, began producing superb data.

Polarimetric approaches are increasingly used in the quest to understand physical processes operating in and around stars. UW was well ahead of the wave, having been a center for polarization studies dating back to the 1940s, when Art Code wrote theoretical papers on polarization radiative transfer.

In the early 1970s, Joe Cassinelli and Nordsieck joined the Department. Cassinelli carried out theoretical models for the intrinsic polarization of stellar envelopes, and Nordsieck developed HPOL, a spectropolarimeter used at the Pine Bluff Observatory. For many years, a major survey of polarization observations was done with HPOL, which provided observing experiences for innumerable undergraduate and graduate students.

Nordsieck and Code proposed a space experiment called WUPPE (Wisconsin Ultraviolet Photopolarimetric Experiment). During the 1990s, it was launched twice with the space shuttle. For the first flight, Nordsieck was a backup astronaut. When technical difficulties arose, he played a critical role in securing good data by continually advising the astronauts on board. WUPPE provided the first ultraviolet observations of polarization.

Over the years, at least ten PhD theses dealing with the interpretation of polarization observations have been written.

A high point of the meeting was the number of friends and colleagues from earlier days in the Department who returned. This group celebrated appropriately at the Memorial Union Terrace.

The meeting was funded by a grant from the National Science Foundation to Richard Ignace (PhD’96), now a professor at East Tennessee State University.

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