COLLOQUIUM: On Tracing the Origins of the Solar Wind
The Sun emits a constant flow of particles from its surface. Mainly composed of Protons and electrons, and dragging with it magnetic fields, this Solar Wind expands outwards from the sun, interacting with planets and spacecraft alike. Since the 1960s, in situ observations have shown that the solar wind is comprised of two distinct states: slow (300550 km/s) and fast (600800 km/s). Temperature, density, and compositional variations between the two suggest different sources for the fast and slow solar wind.
Using state of the art models and observations I find that the solar wind observations used to distinguish between fast and slow solar wind are not as unambiguous as previously thought. The solar wind speed can evolve significantly in the inner heliosphere, confusing source region identification of observations. When the evolution of the solar wind speed is accounted for, it can help explain compositional differences in the solar wind. For Example, the abundance of trace elements, like doubly ionized helium (alpha particles), varies with solar wind speed and time, but it is unclear why or how. Using four years of Wind data, we identify threenot twotypes of solar wind based on alpha particle abundance (AHe). We then show that variations in the AHe with solar wind speed can be explained by the changing frequency of observing these three separate helium populations over time. Using other compositional tracers, we can trace the three populations to the sun and identify possible coronal source regions.
The Princeton Plasma Physics Laboratory 2014-2015 Colloquium Committee is comprised of the following people. Please feel free to contact them by e-mail regarding any possible speakers or topics for future colloquia.
- Carol Ann Austin 609-243-2484