The science of space
Step outside on a clear, cool evening and look up at the stars. Through the ages, people have done just that and wondered: Do other planets exist? What are they like? Who, or what, lives out there?
University of Texas at Arlington astrophysicists Manfred Cuntz and Zdzislaw Musielak have done more than ask the questions. They’re combing the heavens for the answers.
Definitive evidence of planets outside our solar system came just over a decade ago, in 1992, when Alex Wolszczan, a professor at Pennsylvania State University, discovered a planet orbiting a pulsar—a dead star. Professor Wolszczan had found the first extraterrestrial planetary system in the constellation Virgo. Prior to his discovery, people had presumed that planets orbited other stars, but no one had proof.
Building on the work of Dr. Wolszczan and others, in 2000 Drs. Cuntz and Musielak, along with research scientist Steven Saar of the Harvard-Smithsonian Center for Astrophysics, postulated that if a star were orbited very closely by a large, Jupiter-type planet, the planet would actually change the behavior of the star, producing flares, episodic winds and hot spots.
“We predicted that this sort of activity would increase if a giant planet were near the sun,” Musielak explained. “But at the time, people did not believe us. They said, ‘Forget it. This cannot be the case.’ ”
The researchers persisted, even though all observational attempts undertaken by various international teams had failed.
“We thought it would be like moving Jupiter very near the sun,” Musielak said. “But we knew that the sun is much larger than Jupiter, and people said such a planet could not have any effect on a nearby sun. However, we were convinced and we calculated what the effect should be. Ours was a theoretical speculation, based on calculations that this should exist.”
Four years later, their prediction was validated when a Canadian research team, led by Evgenya Shkolnik at the University of British Columbia, identified a strange hot spot, produced by a planet, on the star HD 179949, a sixth-magnitude star 88 light-years away in the Sagittarius constellation.
“This is the first glimpse of a magnetic field of an extrasolar planet,” Shkolnik told an American Astronomical Society press conference last year. The newly discovered planet, unknown at the time of Cuntz, Saar and Musielak’s first prediction, about equals Jupiter in mass and orbits the star at only 10 percent of the distance between the sun and the planet Mercury. Roasting in the heat generated by its host star, it is what the researchers call a “hot Jupiter,” and it behaves precisely as the three theorists predicted it would.
What is the importance of such a distant planet, broiling out in space?
“This opens a completely new realm of extrasolar planetary physics,” Cuntz said. “You can use this type of observation to learn about the planets, especially their magnetic fields and even their interior structure. So far we have discovered about 150 planets around other stars, and there is strong evidence that many more of those planets exist.”
Added Musielak: “Finding planets is a very important part of the human adventure.”
And as planetary discoveries increase, so do the musings on whether planets exist that could support life. Such a planet must lie within an optimal range from its center star, what the researchers call a “habitable zone.” It must also maintain a stable orbit—not be prone to careening off into space.
Life is a delicate matter, and it requires a very particular set of specifications.
“Right now we’re concentrating on the orbital stability of planets that have the potential to have life,” Cuntz said.
Are they out there? Do such planets exist? These UT Arlington professors intend to find out.
— Sherry W. Neaves