Solar Intern Program Project:
 
 Title: Reconstructing Solar flare soft X-ray spectral time series

Type of Project: Data Analysis

Skills/Interest Required: Students that are interested in solar and stellar physics. Basic understanding of electro-magnetic phenomena, soft x-ray detectors, statistics, data reduction methods and analysis techniques will be developed during the project. Students with interest in learning or improving their computer programing skills is required. Students will learn IDL/Python during the project.

Mentor: Dr. Christopher Moore, Dr. Steve Saar

Email: christopher.s.moore_at_cfa.harvard.edu

Background:

Solar flares are eruptions that efficiently accelerate particles, generate waves, create intense radiation and heat plasma to tens of million Kelvin in only a few seconds. The hot plasma readily radiates soft, hard X-rays, and ultraviolet light. Spectral measurements of these high energy photons can be used to deduce the temperature of the plasma in the outer atmosphere of the Sun called the corona. Understanding how this temperature evolves over time provides constraints on the duration of energy release and the degree to which conductive cooling contributes. Furthermore, the solar flare X-ray spectra transmitted through the Earths atmosphere provides constraints on Earth atmospheric constituent density scale heights. This information could be useful for determining future probes of exoplanetary atmospheres.

Project:

In this project the student will commence an investigation of the time evolution of the solar flare plasma temperature inferred from spectrally resolved soft X-ray measurements by the Miniature X-ray Solar Spectrometer (MinXSS) CubeSat. MinXSS has measured over 30 flares to date and a significant number of these flare measurements have gaps in the declining phase of the soft X-ray time profile due to the MinXSS line-of-sight to the Sun being eclipsed by the Earth. These eclipse periods result in 25 35 minutes of lost data (Low-Earth-Orbit). The goals of this project are to:

1. Attempt to reconstruct the solar flare spectral time series of MinXSS eclipse periods (and hence plasma temperature) based on MinXSS non-eclipsed solar flare plasma temperature fits, spectral time profiles, the Geostationary Operational Environmental Satellites (GOES) Soft X-ray Sensor (XRS) integrated flux, and UV proxies.

2. Quantify the change in the soft X-ray spectra, for the largest flares where there are MinXSS measurements attenuated by Earths atmosphere during eclipse egress and ingress. This could provide further insight on soft x-ray diagnostics in future exoplanet studies. The student will use data already download and initially use code already written to analyze the data sets and write their own computer code for analysis of the data.

Figure 1. Left: Time series of MinXSS-1 normalized count rate (symbols) in summed over specific energy bins. The rise time correlates well with the spectrally integrated GOES signal. The declining phase starts to diverge. The MinXSS-1 eclipse time is emphasized for clarity. Right: MinXSS-1 spectra and spectral fit at the peak of the count rate indicated by the black vertical line in the left panel.

   
 

Section Photo