University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Tuesday, April 26th 2016
12:00 pm:
Speaker: Brian Welsch, UW Green Bay
Subject: Effects of Global and Local Magnetic Structure in Flares and CMEs

Processes at work in the initiation and subsequent evolution of solar
flares and coronal mass ejections (CMEs) remain poorly understood.
Improved understanding of such processes could improve Space Weather
forecasts. Here, I will present results from three recent
observational studies of these phenomena. The first study, an
undergrad research project, focused on the relationship between the
emergence of new active regions and the occurrence of flares in
pre-existing active regions (PEARs). Comparing NOAA Solar Region
Summary reports, which record characteristics of active regions
present on the solar disk, with records from NOAA's GOES flare
catalog, we found that the emergence of new active regions is
associated with increased rates of flaring in PEARs. The second
study, also an undergrad research project, aimed to characterize the
relative importance of two factors that had previously been found to
be correlated with CME speeds: (i) the amount of magnetic flux "swept"
out by flare ribbons observed in chromospheric / transition region
spectral lines, conventionally taken to measure the amount of coronal
magnetic flux that reconnected in a flare/CME; and (ii) the rate of
decay, with height, of magnetic field strengths above CME source
regions, estimated from potential models of the coronal magnetic
field. Finally, given sufficient time, I will discuss preliminary
results from an in-progress attempt to replicate the previously
reported correlation of ribbon fluxes versus CME speeds.

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