Dr. Gherardo Valori
We’re well into the new academic year now. Our latest PhD student – Jamie Ryan – has joined us in the solar group to work on sunquakes, which are bursts of seismic activity that are triggered by currently little understood mechanisms. And we have a new senior researcher in the group – Dr. Gherardo Valori. Gherardo will be working with me and Lidia van Driel-Gesztelyi on a Leverhulme Trust funded project called “Solar magnetic activity: bridging the gap between observation and theory”. The project aims to bring together the work Lidia and I do using solar observations to probe the evolution of magnetic fields in the Sun’s atmosphere with Gherardo’s approach of using a computational model of these magnetic fields. By closing the gap between these two approaches we will be able to learn more about how energy is built up and then released to produce events like coronal mass ejections and solar flares.
Solar flares are flashes of radiation across the electromagnetic spectrum and coronal mass ejections blast vast amounts of electrically charged gas and magnetic field into the Solar System. Both phenomena drive space weather here at Earth and so we’re interested in understanding them from a fundamental physical point of view but also to understand more about how living near a dynamic star affects us.
So, over the next four years, I’ll be using observations of the Sun’s atmosphere made in X-ray and ultraviolet light to approach this problem. Gherardo on the other hand will be using the magnetic field measured at the Sun’s visible surface to create what is known as a nonlinear force-free field extrapolation. This allows him to reconstruct the full three-dimensional magnetic field in the region of the atmosphere we are studying. From this reconstruction we can probe how the magnetic field is storing energy and how (and perhaps when) it is likely to be released. Having a three-dimensional reconstruction of the magnetic field also means we can identify the locations where the magnetic field is stressed and see where the energy is stored. These sites are where solar flares and coronal mass ejections form, so if our work goes well, we should see our two approaches converging on what we find. Gherardo’s technique allows the amount of energy that can be released from the magnetic field at these sites to be calculated and by following the magnetic field over time allows us to probe why the energy is released when it is. It’s going to be a busy time.
Well, solar max is here. The Sun has reached the height of its 11-year activity cycle. The peak is important for us because it means solar flares and coronal mass ejections are more frequent (and they create stormy space weather), but it also means that the Sun becomes much more visually interesting. The activity cycle is driven by the Sun’s evolving magnetic field and this most obviously manifests itself at the surface of the Sun as dark and relatively cool features known as sunspots. But in the atmosphere things get much more interesting.
Sunspots are sources of strong magnetic field but they are two a 2D slice of what is a 3D structure. The magnetic field extends from the sunspots up into the atmosphere. The magnetic field extends into the Sun too, but its harder to detect there. In the atmosphere, the magnetic field reveals itself because it traps the million-degree electrically charged gas that comprises the outer layer of the Sun. And this hot gas glows in ultra-violet and X-ray light, illuminating the magnetic structures. The consequence is that we see glowing giant arches rising above pairs of sunspots – analogous to the shapes that iron filings take when scattered around a bar magnetic.
My colleagues at the Naval Research Laboratory (NRL) have made some beautiful images of the Sun showing just how different the magnetised atmosphere looks at the minimum and the maximum phases of the solar cycle. The images are made from data taken by the EIS telescope on the Japanese Hinode satellite. The solar max sections show how the Sun looks in ultraviolet light now, the solar min sections show how the Sun looked a few years ago. You can easily see that at solar max the Sun’s atmosphere is full of magnetic structures in stark contrast to solar minimum. NRL has a long history in solar physics having made their first observations using rockets in the late 1940s. They are still very active in solar physics today. Thanks to Harry Warren, Ignacio Ugarte-Urra and Guillermo Stenborg at NRL for making these stunning images.
My space lab has a new recruit this year. It’s not someone who is here to work on the latest space mission or design a new space instrument though. We have been joined by a poet who will spend the next 12 months finding out about every facet of our work, around which he will write poetry, but more importantly for us he will provide avenues to explore creativity that we may not have thought about before. Our new addition to the lab is the prize-winning poet Simon Barraclough.
We already are a creative bunch at MSSL. We’re always using our imagination to think through the possible areas of science that will lead us to find answers to the questions we have about the Universe. We have to explore the theoretical possibilities and the starting point is having ideas about where to look. Not only do we come up with new ideas about the Universe, we come up with new designs for instrumentation that allow us to gather the data in the first place. Such as the development of the milli-Kelvin cryo-cooler. These are some of the reasons why I enjoy working in space research so much.
It’s not the first time we have had an artist in residence either. A few years back we were lucky enough to work with Joanna Griffin on ‘Satellite Stories’ - a project where, over several months, Joanna gathered the space-related experiences and interests of people both at my lab and outside of any area of research. The project culminated in a story telling evening where we shared our experiences and thoughts in a democratic way as we walked through the MSSL grounds at sunset. It was a departure from our usual public engagement activities and, even though it was rewarding, it also threw up some challenges. We spoke different languages at the start of the project and had different expectations about what should and could be done. However, it’s is a project that I have been wanting to follow-up on. So I was glad that we met Simon.
With Simon we’ll be exploring how the written and spoken word can be used in a scientific community. From my perspective, I want to look at how our scientific writing is shaped by the need to communicate specific and detailed ideas, but how we often include terrestrial terms and analogies to make our extra-terrestrial ideas easier to digest. However, the pictures we paint using these words may conjure up different physical scenarios for different people. I want to see sides of my colleagues (and myself) that are not normally revealed at work because we have been molded by departmental culture. Above all, I want to create an environment where we are stimulated in new ways and challenge our own stereotypes of how scientists can express themselves and communicate. And I want to invite schools and the general public to take part in this.
I hope to give some updates over the coming months and, perhaps a haiku or two.
Lanterns made at the Satellite Stories event. Image courtesy of Joanna Griffin and the Arts Catalyst.
This project would not be possible without the financial support of STFC.