BU Physicist Catches BoingBoing’s Eye

The popular “directory of wonderful things” lauds Opher and her vision of deep space

From BoingBoing

Merav Opher, a College of Arts & Sciences assistant professor of astronomy and a guest NASA investigator, made news recently, predicting when the Voyager space probes will exit the known universe and what the next one might look like.

Opher’s more recent work has revealed what may be an even more complex level of structure in the outer heliosphere. The leading edge is called the heliosheath. It has usually been pictured as a relatively thin, smoothly flowing layer of energized plasma.

But an analysis of Voyager data by Opher and University of Maryland’s James F. Drake in 2011 suggests that the heliosheath is actually a thick cluster of plasma “bubbles” 100 million miles across. The sun’s magnetic field becomes increasingly pleated and folded in the plasma of the outer heliosphere, Opher explains; in the heliosheath, pieces of the magnetic field may detach themselves and reconnect into the self-organized structures of the bubbles.

If Opher’s suggestion holds up to further observations, it could force astronomers to rethink some of their ideas about cosmic rays. “The heliosheath is a shield,” she explains: its plasma stops some highly energetic particles called cosmic rays from entering the solar system. If the heliosheath’s structure is inconsistent, then the shield has holes in it. It might be stopping fewer cosmic rays than has been assumed—or it might be stopping more, if the bubbles absorb the particles more efficiently. A change in either direction could affect astrophysical models about phenomena that produce cosmic rays and the levels of radiation bathing planets around other stars, for example. Read more…

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