My Research

# ForeCAT

Coronal mass ejections (CMEs) are huge explosions of plasma and magnetic field that errupt from the surface of the Sun. When CMEs impact Earth they can affect satellites and electrical systems (in addition to causing pretty aurora). My research has recently focused on the development of a code, ForeCAT (Forecasting a CME's Altered Trajectory), which determines the path a CME takes as it leaves the Sun. ForeCAT calculates the deflection of CMEs due to magnetic forces caused by the background solar wind through which the CME propagates.

# ForeCAT in 3 GIFS

We must describe the radial propagation of the CME - how fast the front moves away from the Sun

Next we describe the rate at which the CME expands as it propagates out radially

The propagation and expansion are currently just simple analytic or empirical models. ForeCAT's primary function is to determine the deflection of a CME. This causes a change in the latitude or longitude of a CME.

The figure at the top shows a selection of CME deflections and rotations. The color contours show the position of active regions which are common sources of CMEs. The line contours show the magnetic field strength further out. Since ForeCAT calculates magnetic deflections the CMEs should deflect toward the location with the minimum magnetic field strength. ForeCAT results show CMEs deflecting to the "magnetic minimum" (which corresponds to the location of the Heliospheric Current Sheet) but the deflections occur in a variety of magnitudes and directions. The bar indicates the orientation of each CME.

While as an Astronomy graduate student my focus is on understanding the science of CME deflections I do rather enjoy the programming aspect of my research. While calculating the forces on a CME at any single time does not take a significant amount of time, the calculations can add up when propagation a CME all the way to the distance of the Earth. The calculation of the background magnetic field turns out to be the most computationally expensive so newer version of ForeCAT make use of a GPU to speed up the calculation. Parallelizing the magnetic field calculation causes ForeCAT to run about 7 times faster and parallelizing the calculation of the forces at each grid point makes ForeCAT run 17 times faster! Such improvements make it more feasible to one day use ForeCAT for real time CME trajectory predictions.

# Papers and Posters

Here are a few items detailing some of my research.

## Papers

Kay, Opher, & Evans (2015) -- The second ForeCAT paper which shows ForeCAT's dependence on the models describing the background solar wind as well as results for multiple Carrington Rotations.

Kay, dos Santos, & Opher (2015) -- Comparison of ForeCAT results with observations of the deflection of the 2008 December 12 CME.

Kay, Opher, & Evans 2013 -- The first ForeCAT paper which describes the details of the model.

## Posters

SHINE 2014 Intro Slide -- Summary of my poster with an image of my most-interesting-man-in-the-world impression.

BU Student Day Poster -- Poster aimed for a general audience so minimial science knowledge necessary! Gives a good description of ForeCAT but contains some outdated results.

SHINE 2012 -- Has earlier work on CME deflections within MHD simulations.