University Advancement

Public Relations and Strategic Communications

MEDIA RELEASE

CSUN Group Sheds Light on Dark Sunspots

(NORTHRIDGE, Calif., Sept. 19, 2007) — The Sun is hot, hot, hot but there are cooler regions on the surface of the celestial body that are not as bright. These dark sunspots, first sighted by ancient Chinese observers around 300 BC and described in 1612 by Galileo after he used a telescope to observe the heavens, are the focus of a series of research papers, authored by scientists and students in the Department of Physics and Astronomy at Cal State Northridge.

The premiere publication in the field, The Astrophysical Journal, which is published by the University of Chicago Press for the American Astronomical Society, featured the first paper in August, and has accepted a second for a future issue. The third paper has been submitted to Solar Physics, the principal journal for the results of fundamental research on the Sun, which is actually the star closest to Earth.

Sunspots have fascinated Debi Prasad Choudhary for 15 years. The assistant professor of physics and astronomy at CSUN coauthored the first paper with K. S. Balasubramaniam, who is with the National Solar Observatory in New Mexico.

"Sunspots are the dark regions of the Sun, which are dark because they are cooler than the rest of the Sun. They are cool because they have an extremely strong magnetic field," Choudhary explained. "These objects are some of the least understood astronomical phenomena of the modern times."

Understanding them matters, according to the scientist, "because they are the sites of solar storms that affect near-Earth space weather, which can disrupt the satellite systems, communications and power grids."

Any disruption could cause trouble with cell phones, credit cards or computers because these items depend on satellites, he explained, and GPS (global positioning system), a satellite-based navigation system. It could also harm a power grid, which provides electricity, by overloading and burning out transformers causing blackouts. Though rare, Choudhary said, that happened in Canada in 1989.

The decay of sunspots is explored in the research paper, coauthored by Na Deng, a CSUN post-doctoral fellow and Choudhary along with collaborators from the New Jersey Institute of Technology and the National Solar Observatory. It is expected to appear in The Astrophysical Journal in two months.

Sunspots become hotter as they decay. That is one of the findings in the paper, submitted to Solar Physics, which reports the research of a former CSUN undergraduate student, Trevor Leonard, who worked with Choudhary and graduated in June. Using observations at CSUN’s San Fernando Observatory, they related the darkness of the sunspots, which look like smudges, to the strength of their magnetic field.

No one knows how sunspots are born, Choudhary said. They appear in 11-year cycles and will be visible in 2010 or so.

California State University, Northridge has 35,200 full- and part-time students and offers 62 bachelor’s and 50 master’s degrees as well as 28 teaching credential programs. Founded in 1958, CSUN is among the largest single-campus universities in the nation and the only four-year public university in the San Fernando Valley. The university serves as the intellectual, economic and cultural heart of the Valley and beyond.