Heloise Stevance

Meet...Heloise Stevance


Name: Dr Heloise F. Stevance  
Job title: Computational Astrophysicist, Eric and Wendy Schmidt AI in Science Postdoctoral Research Fellow 

What are you currently working on? 
When you point a telescope at the night sky, pretty much wherever you look, something new is happening: new lights emerge and fade over time, after travelling millions of years from distant galaxies. Many of these events are stellar explosions, resulting from the death of a massive star (core collapse supernova) or from the merger of very dense neutron stars (kilonovae), or more garden-variety white dwarfs (thermonuclear supernovae). These cosmic catastrophes are part of our own genealogy, as they create chemical elements crucial for life as we know it. My career has been focused on understanding these explosions, whether it be their shape or the life story of stars that created them.  

In the past it was difficult finding these events, as it requries scanning the sky very regularly night after night. Nowadays international telescope surveys such as ATLAS have become very good at finding them, and when the Vera Rubin Observatory opens its dome in the next couple of years, we are expecting to find over a million supernovae every year. Today’s main challenge is therefore to harness the volume of data we are gathering. Classifying stellar explosions is a very important step to enable the science of many teams around the world, but currently this relies heavily on human input. This is a problem for two reasons: 1) We are running out of humans who can do this task 2) Human researchers should be able to focus on creative science tasks rather than tedious data-entry classification. 

As part of the Schmidt AI Fellowship I am creating a Virtual Research Assistant to help humans classify the explosions we detect night after night into their respective categories. This will ensure we make the most of the data our telescopes are gathering and allow researchers to focus on what they do best: science. 

In addition, I remain involved with the stellar evolution theory team in Auckland, New Zealand, and I have access to state-of-the-art simulations of how stars change and evolve throughout their lives – this allows me to retrace the stellar genealogy of explosions detected by typical telescopes and by gravitational wave detectors. This is very exciting as the new observing run of the LIGO/Virgo/KAGRA collaboration has just begun, and as a member of the ENGRAVE collaboration I am involved in following-up visible explosions associated with the invisible gravitational waves.  

Describe a typical day 
Most mornings the first thing I do is grab my bike and head to the gym in the town centre for a weightlifting session or a yoga class. I am hoping to join the rowing team at Reuben college so maybe in the next few months I’ll also be heading to the river for training but when roller derby training is on in the evenings, I will probably try to sleep in a bit more after dawn. 

Then by 8 or 8.30am I make it to the office, switch my sweater for my blazer, put on some make-up and get a nice coffee from the top floor of the Denys Wilkinson building. Typically, there are a few emails I need to tend to, but otherwise I’ll get on with the tasks I had set out the day prior: either fixing some code, maintaining a database or reading a paper. 

During term time the office is buzzing with activities, so by mid-morning there will either be a seminar to attend or a cake and coffee to share with the colleagues. Although it may seem like time away from my work, I find the wealth of community activities in the department really invigorating, and sometimes the best way to fix a piece of code is to step away from it for a little while anyway. Lunch is also a group activity – I will either go to Taylor’s or grab a dish from the canteen and chat with people for 45 minutes before going back to work.  

Between 5 and 5.30 pm I’ll cycle back home, unless there is a dinner at college or with a visitor – which has been a lot more frequent than I would have expected! As a Reuben Associate Fellow, I have been lucky to have access to the fantastic Dining with Dinosaurs event, which starts with a talk at 6pm on a thought-provoking topic (such as the ethics of psychedelics or disability in a post-pandemic world), and is followed by a dinner in the Museum of Natural History where the participants are given two questions relevant the topic to discuss and report on, table by table, at the end of the dinner. On the quieter evenings I spend some time with my flatmate and try to get an early night’s sleep so I can do it all again the next day.  

If you had an entire day at your disposal (not at work), what would be your ideal way to spend it?  
My ideal way to spend time when I’m not at work is to be in Sheffield, where me and my spouse have our flat, cook an exciting new dish with him and bake a cake for the coming week. I also love to take a few hours to myself to go on a long run in the Peak District. Finally, I would spend the rest of the day playing boardgames or a tabletop role-playing game with some friends, or just chilling in front of Bake Off with my better half.  

What is your favourite place in Oxford? 
I’ve not explored all of Oxford yet but right now Croft Road Playground and the surrounding green areas would definitely make top of my list: when I cycle through early in the day when the sun is low, the morning dew sometimes creates a layer of fog over the park that looks mystical. Also, there is an army of ducks still sleeping on the lawn by the playground – I quack at them as I cycle past. 

What discovery would you like to see in your lifetime? 
One thing I would love to see in my lifetime is the confirmed explosion of one of the first stars in the Universe. We call them population III stars (for historical reasons that do not matter) and they are special because they only contain elements made from the Big Bang. Our sun by comparison contains about 2% of elements that are neither hydrogen nor helium, and these “metals” are actually very impactful in how stars live their lives. The population III stars are special because they don't contain iron or other heavy elements: they are much larger (some people think they could be as big as a thousand times the mass of our sun!), burn brighter, die faster, and will on the whole lead to a very different kind of supernova explosion than the types we are accustomed to. They will tell us how the very first heavy atoms of elements such as oxygen, calcium or iron, were created – which will help us understand how the stars we currently see in the Universe came to light up our skies.