Science Seminars

Modeling the Effect of Solar Flares on the Variability of the Extreme Ultraviolet Solar Spectral Irradiance

Speaker: Rachel Hock
Date: Thursday, Apr 26, 2012
Time: 4:00 PM to 5:00 PM
Location: SPSC-N248

Seminar Abstract:

X-ray and extreme ultraviolet (EUV, 0-121.6 nm) emission from the solar corona has long been used to provide insight into the dynamics and evolution of solar flares. The EUV Variability Experiment (EVE) onboard NASA’s Solar Dynamics Observatory (SDO) measures the solar spectral irradiance in the EUV at a wide range of temperatures (7,000 K to 10 MK), capturing the complete evolution of the transition region and corona during solar flares. From 1 May 2010 to 31 August 2011, SDO observed over 750 solar flares. In examining these observations, I discovered that flares could be divided into five EUV flare categories based on their morphology in EUV images. In this talk, I will define these five categories and describe how differences in flare morphology tie changes in the EUV spectral irradiance. I will also present modeling results using the Enthaply-Based Thermal Evolution of Loops (EBTEL) code. For three of the five EUV flare categories, I use the EBTEL code to model the heating rate of representative flares. By fitting the input parameters of the model to EVE data, I determined that the rate of energy release during reconnection strongly influences the EUV irradiance signature. Each of these EUV flare categories has a different heating rate profile, which is related to the underlying magnetic structure of the flare region.