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Gas Giants and Their Influence on the Cosmos and Careers

In a time when astronomers have discovered thousands of exoplanets with a huge diversity of properties, Dr. Marta Bryan is all about gas giants—analogs to Jupiter and Saturn.

“Gas giants are really an obvious place for us to start if we want to learn about the physics of planet formation,” she said, underscoring the outsized influence in shaping the lives of smaller planets through their sheer mass and gravitational pull. “They are prime targets for characterization techniques that can tell us about the planet formation process.”

Marta is an assistant professor at the University of Toronto and a 51 Pegasi b Fellowship alumna (2018). Throughout her career in astronomy, her research has pursued various angles on the origins of gas giants, their intricate interplay with other planetary counterparts, and their dynamic role in the evolution of planetary systems.

Dr. Marta Bryan

After graduating with a Ph.D. in astrophysics from Caltech in 2018, Marta leveraged the financial flexibility the 51 Pegasi b Fellowship provided to delve into uncharted territories of research and foster cross-disciplinary collaborations. One such partnership was with Sivan Ginzburg, a member of her Fellowship class and colleague at UC Berkeley at the time.

“Collaborating with Sivan made my time as a fellow much, much richer,” she said. “As a theorist, he was thinking about complementary things to what I was thinking about observationally. We wrote a paper on planetary spin evolution, and I continue to reach out to him with questions and thoughts.”

Marta credits the Fellowship with enabling her to focus on transformative science while alleviating external pressures, especially during the challenging times of the COVID-19 pandemic. “The funding we were given was very flexible so we could use it to support ourselves as scientists in a more holistic sense,” she said.

Marta’s postdoctoral work spans diverse fronts. One project focused on the intriguing link between super-Earth systems and the presence of Jupiter analogs.

Super-Earth systems “have more Jupiter analogs than you would expect,” Marta said. “This indicates that they are likely signposts of favorable formation conditions. Systems that are able to produce gas giants also naturally form super-Earths.”

In another venture to understand gas giant formation histories, Marta set out to measure planetary obliquity—which describes the tilt of a planet’s axis relative to its orbital plane. Making use of planet rotation period data published by 51 Pegasi b Fellow Yifan Zhou, Marta captured the first- and then second-ever obliquity measures for planets outside our solar system in collaboration with Eugene Chiang at UC Berkeley.

“Obliquity makes the planetary evolution picture so much richer, potentially telling us stories of processes like collisions and accretion of planetesimals,” she said.

Now that she has a faculty position, Marta’s scholarly pursuits continue with studies that delve deeper into planetary formation processes. She is currently working on a radial velocity survey with Ryan Cloutier at McMaster University and Yayaati Chachan at McGill University. The trio hopes to learn more about the role that gas giants play in planet formation around low-mass stars. Another current project of Marta’s compares the atmospheric compositions of directly imaged planets to those of free-floating brown dwarfs of similar ages, masses, and formation conditions.

“It’s another way to tease out something about the formation histories of these supermassive, young, wide-separation objects,” she said.

Next on her exploration agenda: protoplanetary discs, which are pivotal to planet formation. She recently attended the Protostars and Planets conference in Japan and left inspired to further probe this topic.

Marta also eagerly anticipates the advancements enabled by forthcoming technology, including the next generation of ground-based 30-meter telescopes, which are expected to open detailed characterization studies of ice giants and rocky worlds.

Marta’s desire to contribute to the field extends beyond her research. She relishes opportunities to engage with students in her research group as well as the classroom, training the next generation of exoplaneteers. Mindful of diversity, equity, and inclusion issues in astronomy, Marta emphasizes the need for active participation.

“I’m encouraged by the strides we’ve made to educate ourselves about these issues, and I hope that going forward we can keep working to use positions of power and privilege to translate this into actions on the scales we have access to. I think this is a work in progress for all of us,” she said.

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