Image courtesy of NASA
Creating a Comprehensive Solar Picture
The Sun, our nearest star, sustains all life on Earth. But solar flares and more powerful coronal mass ejections regularly release streams of charged particles and high-energy radiation that have a severe impact on our planet — from damaging the electronics in orbiting satellites to disrupting telecommunications and destroying key power-grid components.
For more than a decade, NJIT researchers have been engaged in an expanding range of programs focused on increasing knowledge of the Sun, with a particular emphasis on the drivers of space weather that can adversely affect terrestrial infrastructure. Over the years, this effort has received substantial funding from sources such as the National Science Foundation (NSF) and NASA. A major new NSF grant awarded to Research Professor of Physics Gregory Fleishman as principal investigator will support solar investigation in the radio spectrum, work that will complement other NJIT initiatives dedicated to deepening what we know about the Sun.
On the ground and in orbit
A wealth of relevant data is being acquired at NJIT’s Big Bear Solar Observatory in California, the location of the world’s most powerful ground-based optical telescope designed specifically for studying the Sun. Also owned and operated by NJIT in California, the Expanded Owens Valley Solar Array (EOVSA) will soon provide new capabilities for radio observation of the Sun. Now in orbit aboard the twin NASA Van Allen Probes, an experiment that NJIT had a major role in designing is revealing new information about the Sun’s influence on the Van Allen radiation belts that encompass Earth.
The Center for Solar-Terrestrial Research on campus in Newark is an administrative and analytical focal point for these research initiatives. The NJIT campus also is home to the Space Weather Research Laboratory, which gathers data from Big Bear, Owens Valley, NASA spacecraft, and observatories in other countries to report prevailing solar weather and forecast what’s ahead in the near future.
Funding for coronal insight
Three of the thirteen 2.1-meter antennas at the Expanded Owens Valley Solar Array dedicated to studying the Sun in the radio spectrum. In the distance is one of the two 27-meter antennas at the research facility.
Fleishman will be working on the solar research frontier with co-investigators Dale Gary, distinguished professor of physics, and Gelu Nita, associate research professor of physics. Their new grant provides more than $500,000 for a three-year program dedicated to the modeling and analysis of radio observations that will be taken mainly at the EOVSA. The primary goal is characterization and better understanding of processes that drive solar flares in the coronal region of the Sun’s atmosphere.
The corona is the outermost layer of the solar atmosphere, preceded by the chromosphere and photosphere. Because the photosphere is relatively dense, valuable data can be acquired through optical observation, such as that conducted at Big Bear. But given the more tenuous character of the corona, Fleishman explains, radio imaging is a more useful analytical technique.
Magnetic energy stored in this region, in a magnetized plasma, can be catastrophically released in a matter of seconds. The process believed to underlie this phenomena is known as magnetic reconnection. By observing the Sun at microwave frequencies at the EOVSA, Fleishman anticipates learning much more about how magnetic fields build up and evolve in the corona to drive the eruption of solar flares, plasma heating, and particle acceleration.
Fleishman and his colleagues will work to create a comprehensive, three-dimensional magneto-plasma model that complements optical observation of the Sun, thus expanding the two-dimensional picture of the solar surface into three-dimensional understanding of solar eruptive activity. It would be a significant step toward greater knowledge of the drivers of space weather within our solar system that has such pronounced impacts on Earth. The understanding to be gained from this project also could complement what has been discerned about the energy balance in solar flares through Fleishman’s investigation of the role played by positrons — antimatter particles which, unlike electrons, have a positive electrical charge.
Fleishman points out that the Sun’s proximity to us on the scale of interstellar distances makes it an ideal source of observational data that has implications for our comprehension of phenomena far beyond the solar system. The research into magnetic reconnection to be pursued during the next few years could lead to insights into related processes detected in the solar wind and the tails of comets, and as distant as the center of our Galaxy, and beyond.
Fleishman says that the project also has an educational component, the development of engaging interactive software that could be used in courses to help students comprehend what the research reveals about energy release, and particle acceleration and transport in flares and other solar events. This new teaching tool will invite students to share discoveries important for protecting technology we depend on each day, as well as for deeper understanding of fundamental forces of nature.