posted December 6, 2005

Hope Researchers Participate in NASA Project

Researchers from HopeCollege are participating in a NASA project aimed at understanding the nature of pulsars.

Dr. Peter Gonthier, who is a professor of physics, and his Hope student researchers are part of a NASA-based team that has been seeking to better understand how pulsars, which are highly compact collapsed stars, produce high-energy gamma rays.  The team's project, "High Energy Emission from Pulsar Magnetospheres," recently received a three-year, $341,147 grant from the NASA Astrophysics Theory Program.

The team is headed by Dr. Alice Harding, who is on the staff of the Exploration of the Universe Division of the NASA Goddard Space Flight Center in Greenbelt, Md.  In addition to Gonthier, who has been conducting research with Harding since 1992, co-investigators on the team also include researchers from the Pentagon, RiceUniversity and the University of Nevada at Las Vegas.

The team members, Gonthier said, all contribute in different ways.  For example, he and his students have been running simulations examining the development and behavior of pulsars, and he has also been studying physical processes at the surface of the stars.

"We each have our special niche in the operation, although we do tend to overlap," he said.

Gonthier noted that pulsars are extremely dense neutron stars which have the mass of one and a half of earth's sun packed within a ball 16 miles in diameter.  They rotate rapidly, completing a revolution in a range between once every 10 seconds and a thousand times a second.  Highly magnetized, they shoot out a beam of radiation that, given the spinning, makes the star seem to pulse as the beam passes into view.

"You have this spinning magnet that is able to generate radiation in the form of a beam," Gonthier said.  "If we happen to be in the way of that beam, we will see that star flicker or pulse."

"The challenge, then, is to understand how it works," he said.

Gonthier noted that pulsars were discovered in the 1960s, when scientists observed radio waves coming from them.  The range of electromagnetic radiation, however, is much broader, covering also microwaves, infrared, visible light, ultraviolet light, x-rays and, at the highest end, gamma rays.

He noted that scientists are divided concerning where the gamma rays form on the pulsars.  Harding and her team believe that the activity takes place near the stars' polar caps - at the magnetic poles.  Their research is exploring the idea.

Through the latest grant, which began in October and runs through September of 2008, they are working in conjunction with the GLAST telescope program.  Gamma rays are blocked by the earth's atmosphere and can only be observed from space.  GLAST stands for the "Gamma-ray Large Area Space Telescope," and will study the high-energy cosmos following its launch into orbit, scheduled for 2007.  Gonthier's subgroup has been providing information concerning the simulations they have developed to members of the GLAST team based in Italy.

Gonthier's background is in nuclear physics, but he became interested in pulsars during a 1991 sabbatical in Germany.  He subsequently applied to and was accepted to the NASA JOVE program, which pairs faculty members with NASA scientists on a research project, and began working with Harding.  Their collaboration has extended well past JOVE, including through a previous grant from NASA's Astrophysics Theory Program.

The latest support supplements grants he currently holds from Research Corporation and the National Science Foundation.

Through Gonthier's participation in JOVE, Hope also gained the opportunity to join the Michigan Space Grant Consortium.  Hope is the only undergraduate college that is a member of the consortium, which also includes EasternMichiganUniversity, Grand Valley State University, Michigan State University, MichiganTechnologicalUniversity, OaklandUniversity, SaginawValleyStateUniversity, WayneStateUniversity and WesternMichiganUniversity.

Each summer, Gonthier and two to four students spend four or five weeks at the GoddardSpaceFlightCenter, working directly with Harding and the others on the team in addition to having the opportunity to learn about research that others at the center are conducting.  They then return to campus and continue to work on the project during the summer and the school year as well.

Gonthier has valued the opportunity to involve his students in the international effort, giving them not only the opportunity to participate in the research itself but also to share their own work with others. "This work is taking students to professional meetings where they are presenting their results," he said.

The current Hope students who worked with him this past summer are sophomore Ruth Arevalo of Brookfield, Wis.; senior Brenna Giacherio of Englewood, Ohio; and senior Sarah Story of Glendale Heights, Ill.  Giacherio and Story have also continued to work on the project during the school year.