Illuminating Eclipses

Solar physicists have known for more than a century that the surface temperature of the Sun is between 5,000 and 6,000 degrees K, but what they are less sure about is why the temperature of the Sun’s atmosphere, known as the corona, is so much hotter—millions of degrees hotter, in fact. Much of what solar physicists know about the corona comes from high-resolution photos taken during total solar eclipses when the corona is most visible.

Muzhou Lu ’13 has dedicated three summers and his senior thesis to tracking total solar eclipses to study the Sun’s corona. Lu’s research culminated at this year’s American Astronomical Society (AAS) meeting in Bozeman, Mont. Lu won the Solar Physics Division (SPD) poster competition for his presentation, “Observations and Modeling of Solar Coronal Structures Using High-Resolution Eclipse Images and Space-based Telescopes with Wide Field-of-View.”Muzhou.intext

Lu’s work seeks to address problems and limitations with traditional models and observation methods. Among other things, he linked space-based images of solar eclipses with ground-based ones in new ways, showing potential for comparing them in studying the structures of the corona.

Lu’s was one of 24 entries in the competition, and one of two from undergraduate students.

“Muzhou has been wonderful all year—so bright, active, and capable with all matters of science and computing,” says Lu’s senior thesis advisor, Jay Pasachoff, the Field Memorial Professor of Astronomy. “Now, from the fact that he won the Solar Physics Division’s student poster competition over a whole bunch of grad students, I am not surprised to find that he is remarkable on a nationally comparative scale, too.”

Lu, a double major in astrophysics and art, made three trips to observe solar eclipses during his Williams career. Two of those trips, one accompanying Pasachoff to Easter Island in the South Pacific after Lu’s freshman year, and another to Australia in 2012, served as comparisons for his thesis project. Lu used what he learned in further study in 2012 at the Harvard-Smithsonian Center for Astrophysics and during Winter Study 2013 at the Royal Observatory of Belgium—about modeling techniques and solar data processing—in his thesis project, which aimed to capture what the corona looks like in visible and extreme ultraviolet light.

Co-authors on Lu’s prize-winning poster include Pasachoff, his senior thesis advisor; Daniel B. Seaton ’01, who is now deputy director of a European Space Agency solar spacecraft project; Yingna Su and Aad Van Ballegooijen, Lu’s advisors at the Harvard-Smithsonian Center for Astrophysics; and Royal Observatory of Belgium astronomer Matthew West. “Collaboration is a huge part in any area of research,” Lu says. “I’m glad [Professor Pasachoff] has shown me just what can be achieved through collaboration.”

Lu is spending the summer at Williams, conducting planetarium shows and working with Pasachoff on a journal article based on Lu’s thesis findings. In the fall, Lu will be teaching physics and math, as well as art and rock climbing, at an independent school in Maryland.