October 14, 2005

Prof Sheds Light on Stars

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Prof. Andrew Cumming, astrophysics, McGill University, spoke to a full classroom in the Space Sciences building about new methods of studying neutron stars yesterday afternoon.

Cumming, who received his professorship at McGill only last year, is himself a rising star in the field. He graduated from the University of Cambridge, then went on to receive his doctorate from U.C. Berkeley in 2000. Much of the research presented in Cumming’s lecture was derived from his post-doctoral fellowship at U.C. Santa Cruz, which he held from 2000 to 2001.

Cummings spoke primarily about the use of “thermonuclear flashes,” or extremely short and concentrated bursts of X-ray energy released from the surface of a star. According to Cumming, these flashes occur when gaseous mass accumulating around the outside of the star reaches a “critical thickness.”

“The bursts go off like clockwork; every six hours, you see a burst,” Cumming said, referring to the reliability of these energy flashes. He explained that the significance of the bursts is that they cause their stars to become visible over the “accretion luminosity,” or the brightness of the accumulating matter that stars grow in.

However, the bursts are extremely short, lasting only about ten seconds. This gives astrophysicists only a limited window to examine each flash.

“For ten seconds each day, I can study the neutron star,” Cumming said.

Cummings also spoke about a phenomenon called a “superburst,” which has been observed only within the last five years. According to Cumming, these superbursts occur on a much longer time scale, about ten hours, thus providing a much larger span for observation. The drawback, however, is that superbursts occur far less frequently.

“There have been 14 [superbursts] recorded in the whole human history,” Cumming said, adding that this low number is due to the fact that the capability to examine superbursts has not existed until very recently.

The lecture drew a number of prospective space sciences majors who were interested in Cumming’s research.

“We’re very interested in astronomy and space science,” said Nick Stone ’08. “They have these lectures here every Thursday, and they’re usually fascinating.”

“I’m about to go ask him if he has any internships,” said Ben Holmes ’08, who concurred with Stone’s comments.

Cumming’s lecture was part of the Astronomy and Space Sciences Fall 2005 Colloquium Series.

Archived article by Chris Barnes
Sun Contributor