Planetary Nebula Discovery And Formation Of Spiral Galaxies Focus Of Collaboration Funded By NSF
WILLIAMSTOWN - The National Science Foundation has awarded a three-year grant totaling $583,000 to Williams College Professor of Astronomy Karen Kwitter and two longtime colleagues, Bruce Balick of the University of Washington, and Richard Henry of the University of Oklahoma.Their project, titled, "Planetary Nebulae as Probes of the Early Chemical History of the Galaxy and M31," is a collaborative effort, involving a team of astronomers from the U.S., Great Britain and Italy, and includes undergraduate and graduate students as important participants.
By studying the distribution of the chemical elements in planetary nebulae, which are shells of gas cast off by sun-like stars as they die, the astronomers can uncover patterns of chemical enrichment that yield clues to how spiral galaxies were formed and how they have developed. A planetary nebula is a kind of "time machine": its chemical abundances reveal the composition of the Galaxy at the time and place where its ancestral star was formed billions of years in the past.
Carrying out this ambitious project will require, among other efforts, a search for previously undetected planetary nebulae in the outlying regions of the Milky Way Galaxy and M31 (the Andromeda Galaxy), followed by observations of their spectra to determine their chemical compositions.
A pilot project to derive chemical abundances in known planetary nebulae in the outer reaches of the Milky Way has already been done, as detailed in the senior honors thesis of Williams student Anne Jaskot '08, being readied for publication. The analysis package the team will use to calculate chemical abundances was designed by Jesse Levitt '08 and Keck Northeast Astronomy Consortium exchange student, Matthew Johnson (Wesleyan '07).
An important legacy product of this work has already begun. The "Gallery of Planetary Nebula Spectra" website created by Kwitter and Henry and designed by the Williams Instructional Technology (WIT) summer interns, http://www.williams.edu/Astronomy/research/PN/nebulae presents high-quality spectra and related information for more than 120 planetary nebulae in the Milky Way, and also includes pedagogical information about planetary nebulae and three custom-written student exercises making use of "Gallery" spectra.
Part of this project will involve adding newly discovered nebulae to the database and incorporating chemical abundance information. With over 13,000 hits, the website is used as a research tool by professional astronomers as well as a teaching resource for astronomy classes.
Kwitter is the Ebenezer Fitch Professor of Astronomy and the author or co-author of more than 50 scientific papers and four books. She studies the end stages of stellar life and the origin of the chemical elements in our galaxy. More details are available at her website: http://www.williams.edu/Astronomy/people/kkwitter/.
