Professor plays key role in showing how gas escapes Milky Way Galaxy
Released: May 19, 2008
When you hear the words “milky way” you think of the candy bar, right? Not the case for University of Wisconsin – Whitewater Assistant Professor of Physics Robert Benjamin. To him, the Milky Way Galaxy is much more. “It’s about the thrill of discovery,” he says.
And discover he has. Recently, Benjamin found that cosmic rays are causing the Milky Way Galaxy to shed gas, a characteristic previously associated with much more active star-forming galaxies than the Milky Way.
His recently co-authored paper presents a model of how the gas and dust between the stars of the Milky Way Galaxy can be heated by supernova explosions to such a high temperature that the gas ends up continuously flowing out into intergalactic space in a process called a Galactic Wind. Part of his work was featured in the “News & Views” section of the April 17, 2008 issue of Nature, which highlights interesting or important scientific work in a variety of fields.
“This was a very gratifying paper for me because it was a problem that I couldn’t initially solve,” said Benjamin. “When I first came to Wisconsin, I worked on trying to model such a wind, but I could never get the gas to escape the Galaxy. As it turns out, adding cosmic rays into the mixture solved this long-standing problem.”
The paper, done in collaboration with John Everett, Ellen Zweibel, Dan McCammon, Lindsay Rocks and John Gallagher, astrophysicists at UW-Madison, show how we may see evidence of gas being blown out of the Milky Way by stellar explosions. It's a complementary process to another recent discovery of gas crashing into the Galaxy from intergalactic space. The newest paper, “The Milky Way’s Kiloparsec-Scale Wind: A Hybrid Cosmic-Ray and Thermally Driven Outflow,” was published this year in The Astrophysical Journal.
Earlier this year, Benjamin was recognized for gathering information and images about a giant cloud of hydrogen gas headed toward the Milky Way Galaxy. Smith’s Cloud is about a million times larger than the mass of the sun. It is projected to collide with the Galaxy in approximately 20-40 million years.
For more information on Benjamin’s research or the Milky Way Galaxy, contact Robert Benjamin at benjamir@uww.edu or 262-472-5114.
- Ashley Jones,jonesac08@uww.edu
