Modelling and Multi-wavelength Observations of Solar Flare Heating

Lead Research Organisation: University of Glasgow
Department Name: School of Physics and Astronomy

Abstract

Our Sun is perceived to be a fairly benevolent star, bathing our planet in live-giving heat and light. But every 11 years or so, its behaviour changes, from quiescent to turbulent and back again. During periods of increased activity the Sun's twisted and contorted magnetic field continually undergoes episodes of complex reconfiguration to liberate vast quantities of pent-up energy. This energy goes into heating the solar plasma to temperatures of tens of millions of degrees and accelerating particles to near-relativistic velocities. Precisely how this energy conversation takes place remains an open question, and I aim to tackle this problem over the course of this Fellowship by capitalising upon the most advanced theoretical models and observational datasets currently available.

Modern society is becoming increasingly dependent upon evermore advanced technologies. These systems, such as satellite communication, national power grids, and the Global Positioning System (GPS), are all susceptible to changes in the Sun's behaviour; more commonly referred to as space weather. Space weather typically comprises two phenomena: solar flares and coronal mass ejections (CMEs). CMEs are clouds of charged particles ejected off the Sun at millions of miles per hour, reaching the Earth in 2-3 days, where they can interfere with electrical systems and generate spectacular aurora, while solar flares are intense bursts of radiation that span the entire electromagnetic spectrum from radio waves to gamma-rays. This radiation traverses the Sun-Earth distance in just 8 minutes, and the ultraviolet (UV) component is known to change the composition and dynamics of our atmosphere. This can affect the motion of satellites in low Earth orbit, disrupt long-wave radio communication, and affect the transmission of GPS signals.

During solar flares, much of the UV radiation is emitted by the chromosphere; a dense layer between the Sun's visible photosphere and the tenuous outer corona. The chromosphere is also where the bulk of a flare's energy emanates during its initial stages, and is the origin of material that occupies the overlying coronal loops. However, the mechanism by which the released energy gets transferred to the lower solar atmosphere remains elusive. It is commonly assumed that the delivery mechanism is a beam of high-energy electrons, and yet these particles are unable to penetrate to the depths at which the most energetic emission is believed to originate. Other proposed processes include heat conduction, relativistic ions, magnetic waves, or radiative backwarming. Fortunately, much of the radiation emitted contains a wealth of diagnostic information with which to probe the heated plasma. This allows us to distinguish between various heating mechanisms by measuring changes in temperature, density, velocity, etc, and comparing them to the predictions of theory.

While solar flares may emit radiation across the entire spectrum, our spectral coverage is somewhat lacking in parts. Most remote sensing instruments - both in space and on the ground - are often designed to look at a very limited wavelength range. Therefore in order to build a more complete picture of the flaring solar atmosphere, coordinated observations between different instruments are crucial. A core goal of this research is therefore to search for and catalog flaring events observed by a variety of instruments simultaneously, as well as planning future coordinated observing campaigns. For parts of the spectrum that are not yet observable, outputs from numerical simulations shall be used to fill in the gaps. This will help to prepare for instrumentation that will come online during the course of the project. Similarly, there are regions of stellar flare spectra that are unobservable due to absorption by the interstellar medium. The outcomes of this research shall assist in characterising this emission on other stars, especially that which can affect exoplanet atmospheres.
 
Description Lord Kelvin Adam Smith Research Fellowship
Amount £100,000 (GBP)
Funding ID 200490-01 
Organisation University of Glasgow 
Sector Academic/University
Country United Kingdom
Start 03/2017 
End 02/2022
 
Title Skylab NRL SO82B calibrated data of the flare SOL1973-09-07 and plage observed on 1973-09-11 
Description  
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Solar Flare Finder 
Description Solar Flare Finder is an interactive widget available in SSWIDL (SolarSoftWare Interactive Data Language). It allows a user to search for solar flares observed by various combinations of space-based instruments to answer specific science questions. They can also search by magnitude, location on the solar disk, etc. The database itself is hosted by the RHESSI group at NASA Goddard Space Flight Centre. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
Impact The creation of this database allowed us to provide a statistical analysis of how well the solar physics community have been performing in capturing solar flares with various combinations of space-based instrumentation. The findings were published in Milligan & Ireland (2018). 
URL https://hesperia.gsfc.nasa.gov/sff/
 
Description NASA/GSFC 
Organisation National Aeronautics and Space Administration (NASA)
Department Goddard Space Flight Center
Country United States 
Sector Public 
PI Contribution I led two distinct research projects that involved collaborators at NASA/GSFC. 1) the detection of 3-minute oscillations in full-disk Lyman-alpha emission during a major solar flare, and 2) a quantitative analysis of multi-instrument solar flare observations, and an interactive widget that allows a user to search for solar flare datasets spanning multiple instruments. Portions of these projects, such as travel to NASA/GSFC and to conferences in the US to present the findings, were funded under my previous NASA Living With A Star research grant, which is administered by the Catholic University of America.
Collaborator Contribution 1) Drs. Ireland and Fleck are leading experts in wave phenomena in the solar atmosphere, and their contribution was invaluable to the interpretation of the analysis that I had conducted. 2) Dr Ireland also has background in statistics, which was vital in evaluating how successful (or otherwise) the solar flare community have been in coordinating observations of flares. Kim Tolbert also helped develop the interactive widget, and set up hosting and automating of the underlying code to be constantly updated on servers at NASA/GSFC.
Impact Two refereed publications to date. Milligan et al. (2017) and Milligan & Ireland (2018).
Start Year 2016
 
Description AGU 2017 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact In December 2017 I presented a poster at the American Geophysics Union meeting in New Orleans. My findings included the detection of a 3-minute oscillation in hydrogen Lyman-alpha emission during a major solar flare. This was detected in full-disk irradiance measurements indicating that these oscillations could contain significant amount of energy.
Year(s) Of Engagement Activity 2017
URL https://fallmeeting.agu.org/2017/
 
Description BBC Documentary: Space Truckers 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact My occupation prior to being a scientist was as a truck driver. I wanted to combine these two skill sets to create a "reality style" TV show where I would be hauling a piece of scientific/astronomical equipment, while explaining its significance to the audience during the journey. In April 2017 I ended up hauling the "brains" of the Irish LOFAR (I-LOFAR) radio telescope from the Netherlands to Ireland. This haul was documented by Stellfy Media/Sony for BBC Northern Ireland and aired in December 2017.
Year(s) Of Engagement Activity 2017
URL http://www.bbc.co.uk/programmes/b09hls66
 
Description Cafe Scientifique 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact General public talk on the current state of solar activity and the recent total solar eclipse across the continental United States.
Year(s) Of Engagement Activity 2017
URL https://www.gla.ac.uk/events/cafescientifique/events/past/thesleepinggiantthecurrentstateofsolaracti...
 
Description Down Recorder newspaper article 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact The local newspaper in the town that I grew up - The Down Recorder - did an article on me ahead of the airing of my BBC documentary "Space Truckers".
Year(s) Of Engagement Activity 2017
URL http://thedownrecorder.co.uk/pages/?title=Space_Truckers_Ryan_on_small_screen_moving_computer_across...
 
Description GIST Podcast 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact After giving a Cafe Scientifique talk at Waterstones, Glasgow, I was approached by the Glasgow Skeptics to do a podcast for Glasgow Insight into Science and Technology (GIST) on the current state of solar activity and the recent total solar eclipse across the continental Unites States.
Year(s) Of Engagement Activity 2017
URL https://the-gist.org/podcast/podcast-18-cafe-scientifique-sleeping-giant/
 
Description Interview for Radio Ulster 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact As publicity for my BBC show, Space Truckers, I did a live (trans-Atlantic) interview with Gerry Kelly for Radio Ulster.
Year(s) Of Engagement Activity 2017
URL http://www.bbc.co.uk/programmes/b09h66tz
 
Description Invited talk at SunDC meeting on Exoplanet Space Weather 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I was invited to give a talk on Sun-As-A-Star observations of solar flares at Johns Hopkins University, Maryland, and how they may relate to stellar flares and their influence on exoplanets.
Year(s) Of Engagement Activity 2018
URL https://pyoung.org/gsfc/SUNDC%202018_v1-1.pdf
 
Description NASA Press Release 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact NASA issued a press release on my discovery of oscillations in the solar chromosphere in response to a major solar flare.
Year(s) Of Engagement Activity 2017
URL https://www.nasa.gov/feature/goddard/2017/nasa-detects-solar-flare-pulses-at-sun-and-earth
 
Description NASA Press Release on Space Truckers 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact NASA issued a press release on my transition from truck driver to astrophysicist, and on my BBC Documentary "Space Truckers" in which I hauled the supercomputer that would drive the I-LOFAR radio telescope, from the Netherlands to Ireland.
Year(s) Of Engagement Activity 2017
URL https://www.nasa.gov/feature/goddard/2017/ryan-milligan-on-the-open-road-to-the-universe
 
Description Poster at AGU meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I presented a post on my work on Lyman Continuum Observations of Solar Flares Using SDO/EVE at the Americal Geophysical Union meeting in Washington DC.
Year(s) Of Engagement Activity 2018
URL https://fallmeeting.agu.org/2018/
 
Description Poster at NAM/EWASS 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I gave a poster on the detection of 3-minute oscillations in hydrogen Lyman-alpha emission in response to a major solar flare at the National Astronomy Meeting/European Week of Astronomy and Space Science in Liverpool, UK.
Year(s) Of Engagement Activity 2018
URL https://eas.unige.ch/EWASS2018/
 
Description RAS Solar Orbiter Working Group 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact In November 2017 the RAS hosted a working group for the upcoming Solar Orbiter mission. I gave a brief presentation on the recent discovery of oscillations in hydrogen line emission during a solar flare. The EUI instrument on Solar Orbiter will routinely observe this emission and so knowledge of these oscillations could be important for the interpretation of future science results.
Year(s) Of Engagement Activity 2017
URL https://www.ras.org.uk/component/gem/?id=484
 
Description RHESSI XVI 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I gave a talk on the detection of 3-minute oscillations in hydrogen Lyman-alpha emission in response to a major solar flare at the 16th RHESSI workshop in Boulder, CO. I was also on the Scientific Organising Committee for this workshop.
Year(s) Of Engagement Activity 2017
URL https://rhessi16.boulder.swri.edu
 
Description Talk at Space Glasgow meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact I gave a talk on my BBC documentary, Space Truckers, as a way of making connections in the space industry to solicit potential projects that could be filmed for further future episodes. As a result, I was invited to the Skyrora company in Edinburgh to view their rocket assembly workshop, and also to give a talk at the UK Space Careers conference.
Year(s) Of Engagement Activity 2018
URL https://www.eventbrite.com/e/2nd-space-glasgow-research-conference-tickets-50266239676
 
Description Talk at TESS/SPD meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I gave a talk at the Triennial Earth-Sun Summit in Lessburg, Virginia on Multi-Instrument Solar Flare Observations During Solar Cycle 24.
Year(s) Of Engagement Activity 2018
URL https://connect.agu.org/tess2018/home
 
Description Talk at the National Student Space Conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Undergraduate students
Results and Impact I was invited to give a talk at the National Student Space Conference in Edinburgh, UK on my career path from truck driver to NASA scientist. Many students said that they were inspired by my talk.
Year(s) Of Engagement Activity 2019
URL https://ukseds.org/aurora/?p=nssc2019
 
Description Talk at the SDO Science Workshop 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I gave a talk about my recent research on Lyman Continuum Observations of Solar Flares Using SDO/EVE, at the SDO Science Workshop in Ghent, Belgium.
Year(s) Of Engagement Activity 2018
URL https://register-as.oma.be/sdo2018/
 
Description Washington Post Q&A for the Total Solar Eclipse 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact I was approached by the Washington Post to partake in a live online Q&A session ahead of the total solar eclipse across the continental United States in August 2017. I answered questions from the general public on all aspects of this event.
Year(s) Of Engagement Activity 2017
URL https://live.washingtonpost.com/qa-eclipse-coverage-live-20170815.html?hpid=hp_no-name_no-name%3Ahom...