This text is part of the special Research section
Last December, a team of scientists led by Caroline Piaulet, doctoral student in astrophysics at the Trottier Institute for research on exoplanets, published an article in the journal Nature Astronomy. Their discovery: two exoplanets located 218 light years from Earth would be largely composed of water.
“The article explains that these exoplanets are not just big balls of rock, but they are not gaseous planets either,” says Caroline Piaulet, a student at the University of Montreal. They have a density between the two and similar to water. We already thought that planets like these could exist since water is very abundant in the universe, but before, we were not able to observe them. This discovery prompts us to examine 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 constellation of Lyra. The article, titled “ Evidence for the volatile-rich composition of a 1.5-Earth-radius planet » , is co-authored by Caroline Piaulet, Björn Benneke and Diana Dragomir, from the University of New Mexico, and by other co-authors from France, the United States and Austria.
Path of the astrophysicist
Arriving in Quebec eight years ago, Caroline Piaulet completed her bachelor’s degree in physics at the University of Montreal. In 2019, she went directly to the doctorate in astrophysics and studies exoplanets, i.e. planets that revolve around stars other than the sun and which are located outside the solar system.
“The goal of my research is to better understand the composition of the exoplanets that we know,” says Caroline Piaulet. We now know more than 5000 of them, but for the most part, we don’t know much, except their size. We don’t know their mass and composition, or even what their atmosphere is made of. My mission is to observe these exoplanets to find out more. For some time I’ve been working on planets that are a bit larger than Earth and which are thought to be largely made of water or methane. »
To study them, she uses modeling and data analysis, as well as data from space telescopes. Currently, she is 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 are starting to have data from this telescope. What is game-changing with James Webb are all the types of molecules he is able to 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 detect water and methane, but with James Webb, we can see other molecules, for example carbon monoxide, carbon dioxide, ammonia. »
The doctoral student is part of a group called Early Release Science. “It allowed us to get the first observations from James Webb to analyze them 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 is an organization that allows young people in high school and CEGEP to do research themselves, while being mentored by scientists in graduate school, she says. The objective is to awaken them to science, but also to make them understand that they are capable of doing research. For example, at the moment, the young people I work with are studying exoplanets that we already know, but whose composition we would like to know. Others study cell biology. Everything varies depending on the mentors that are recruited each year. It is a mission that is close to my heart. »
The small team is currently working on a system called TRAPPIST-1. “It’s a star around which revolve seven planets, and these have about the same mass as the planet, says Caroline Piaulet. With the team of which I am the mentor, we are trying to understand what these planets would be made of thanks to data from the James Webb telescope. »
For the astrophysicist, it is particularly exciting to work in this field, at a time when a powerful telescope like James Webb is beginning to provide data. “It’s really amazing to do research at the start of my career, at this particular time,” she says. I expect that over the next five to ten years it will be a real game-changer. »
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