This text is part of the special research section
Last December, a team of scientists led by Caroline Piaulet, a PhD student in astrophysics at the Trottier Institute for Research on Exoplanets, published an article in the journal Nature Astronomy. Their discovery: Two exoplanets 218 light-years from Earth would be mostly made of water.
“The article explains that these exoplanets are not only large rocky spheres, they are also not gas planets,” says Caroline Piaulet, a graduate student at the University of Montreal. They have a density between the two and similar to water. We already thought that there might be planets like this since water is very abundant in the Universe, but we couldn’t see them before. This discovery prompts us to study other planets to see if we could find any with a similar composition. »
These two exoplanets are part of a planetary system known as Kepler-138, located in the Lyra constellation. The article entitled “Evidence for the volatile-rich Composition of a 1.5-Earth-radius planet” was co-authored by Caroline Piaulet, Björn Benneke and Diana Dragomir from the University of New Mexico and other co-authors from France, the United States and Austria.
way of the astrophysicist
Caroline Piaulet came to Quebec eight years ago and received her BS in Physics from the University of Montreal. In 2019 she received her PhD directly in astrophysics and studies exoplanets, i.e. planets orbiting stars other than the sun and located outside the solar system.
“The goal of my research is to better understand the composition of the exoplanets known to us,” says Caroline Piaulet. We now know more than 5000 of them, but for the most part we don’t know much other than their size. We do not know their mass and composition, nor do we know what their atmosphere is made of. My mission is to observe these exoplanets to find out more. For some time I have been working on planets slightly larger than Earth that are thought to be mostly water or methane. »
To study them, she uses modeling and data analysis, as well as data from space telescopes. She is currently working on data provided by the James Webb Telescope, the most complex and powerful ever built.
“Previously I had worked on other space telescopes like Hubble or Spitzer, but since last year we’ve been starting to have data from this telescope. What is groundbreaking about James Webb is all the types of molecules that he can detect in a planet’s atmosphere. Each molecule has a signature in the light we receive, a bit like a fingerprint. With Hubble we could see water and methane, but with James Webb we can see other molecules, for example carbon monoxide, carbon dioxide, ammonia. »
The PhD student is part of a group called Early Release Science. “It allowed us to obtain the initial observations from James Webb to analyze and provide best practices to the rest of the scientific community. »
Making research accessible to young people
The researcher is also president of the organization Initiasciences, which she founded in 2021. “It’s an organization that allows young people in high school and CEGEP to do their own research while being mentored by scientists in graduate school,” she says. The aim is to awaken them to science, but also to make them understand that they are capable of doing research. For example, the young people I work with are currently studying exoplanets that we already know about but whose composition we would like to know. Others study cell biology. Everything depends on the mentors who are recruited every year. It’s a mission close to my heart. »
The small team is currently working on a system called TRAPPIST-1. “It’s a star with seven planets orbiting it, and they’re about the same mass as the planet,” says Caroline Piaulet. With the team I’m mentoring, we’re trying to understand what these planets would be made of thanks to the data from the James Webb telescope. »
Working in this field is particularly exciting for the astrophysicist at a time when a powerful telescope like James Webb is beginning to provide data. “It’s really amazing to be doing research early in my career, right now,” she says. I expect it will be a real game changer in the next five to ten years. »
This special content was created by Le Devoir’s Special Publications team, reporting to Marketing. Le Devoir’s editorial staff did not take part.