Exoplanets Discovered Around New Star Reveal Secrets of Planet Formation

Six-exoplanet system offers glimpse into planet formation and evolution.

With an arsenal of advanced technology, scientists have found a multi-planet star system that provides a rare insight into the way planets form and behave around a young star.

TOI-1136 is a dwarf star in the Milky WayThe Milky Way is the galaxy that contains our Solar System and is part of the Local Group of galaxies. It is a barred spiral galaxy that contains an estimated 100-400 billion stars and has a diameter between 150,000 and 200,000 light-years. The name "Milky Way" comes from the appearance of the galaxy from Earth as a faint band of light that stretches across the night sky, resembling spilled milk.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>Milky Way galaxy more than 270 light-years from Earth, which is considered nearby, as the Milky Way is 100,000 light years in diameter. There are six confirmed planets orbiting the star, and scientists strongly suspect the presence of a seventh.

“Because few star systems have as many planets as this one does, it’s getting close in size to our own solar system,” said Tara Fetherolf, visiting assistant professor of astrophysics at Cal State San Marcos and co-author of a new paper about the system. “It’s both similar enough and different enough that we can learn a lot.”

Insights From the TOI-1136 System

Published on January 29 in The Astronomical Journal, the paper offers precise measurements of the exoplanets’ masses, details about the shape of their orbits, and characteristics of their atmospheres. Details like these were built upon initial observations of the system from 2019 using data from the Transiting Exoplanet Survey Satellite, or TESSLaunched on April 18, 2018, aboard a SpaceX Falcon 9 rocket, NASA’s Transiting Exoplanet Survey Satellite (TESS) is a space telescope mission to search nearby stars for undiscovered worlds with a goal of discovering thousands of exoplanets around nearby bright stars.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>TESS.

Artist rendering of the TOI-1136 system and its young star flaring. Credit: Rae Holcomb/Paul Robertson/UCI

Stephen Kane, UC Riverside planetary astrophysics professor and principal investigator of the TESS Keck Survey, explains how the newly discovered system differs from many other known systems. To begin with, its age sets it apart. At a mere 700 million years old, it’s very young compared to our own solar system, which is 4.5 billion years old.

“This gives us a look at planets right after they’ve formed, and solar system formation is a hot topic. Any time we find a multi-planet system it gives us more information to inform our theories about how systems come to be and how our system got here,” Fetherolf said.

Challenges and Achievements in Studying Young Star Systems

Juvenile stars are both difficult and special to work with because they’re so active. Magnetism, sunspots, and solar flares are more prevalent and intense during this stage of a star’s development, and the resulting radiation blasts and sculpts planets, affecting their atmospheres.

“Young stars misbehave all the time. They’re very active, just like toddlers. That can make high-precisions measurements difficult,” Kane said.

All the planets are of a similar age in the system, and formed under similar conditions. “This will help us not only do a one-to-one comparison of how planets change with time, but also how their atmospheres evolved at different distances from the star, which is perhaps the most key thing,” Kane said.

Because all the planets in this system are relatively close together, the research team was also able to measure something that is hard to gauge in other systems.

“Normally when we’re looking for planets, we’re looking at the effect the planets have on their star. We watch the star move around and interpret that as the gravitational effects the planets are having on it. Here, we can also see the planets pulling on each other,” Kane said.

Using the Automated Planet Finder telescope at the Lick Observatory on California’s Mount Hamilton and the High-Resolution Echelle Spectrometer at the W.M. Keck Observatory on Hawaii’s Mauna Kea, the researchers detected slight variations in stellar motion that helped them determine the mass of the planets with unprecedented precision.

To obtain such exact information on the planets, the team built computer models using hundreds of observed velocity measurements layered over transit data. Corey Beard, lead author of the paper and a UC Irvine Ph.D. candidate in physics, said combining these types of readings yielded more knowledge about the system than ever before.

“It took a lot of trial and error, but we were really happy with our results after developing one of the most complicated planetary system models in exoplanetAn exoplanet (or extrasolar planet) is a planet that is located outside our Solar System, orbiting around a star other than the Sun. The first suspected scientific detection of an exoplanet occurred in 1988, with the first confirmation of detection coming in 1992.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>exoplanet literature to date,” Beard said.

Reference: “The TESS-Keck Survey. XVII. Precise Mass Measurements in a Young, High-multiplicity Transiting Planet System Using Radial Velocities and Transit Timing Variations” by Corey Beard, Paul Robertson, Fei Dai, Rae Holcomb, Jack Lubin, Joseph M. Akana Murphy, Natalie M. Batalha, Sarah Blunt, Ian Crossfield, Courtney Dressing, Benjamin Fulton, Andrew W. Howard, Dan Huber, Howard Isaacson, Stephen R. Kane, Grzegorz Nowak, Erik A Petigura, Arpita Roy, Ryan A. Rubenzahl, Lauren M. Weiss, Rafael Barrena, Aida Behmard, Casey L. Brinkman, Ilaria Carleo, Ashley Chontos, Paul A. Dalba, Tara Fetherolf, Steven Giacalone, Michelle L. Hill, Kiyoe Kawauchi, Judith Korth, Rafael Luque, Mason G. MacDougall, Andrew W. Mayo, Teo Močnik, Giuseppe Morello, Felipe Murgas, Jaume Orell-Miquel, Enric Palle, Alex S. Polanski, Malena Rice, Nicholas Scarsdale, Dakotah Tyler and Judah Van Zandt, 29 January 2024, The Astronomical Journal.
DOI: 10.3847/1538-3881/ad1330

Joining UC Irvine and UC Riverside on this study were researchers from Spain’s Astrophysics Institute of the Canary Islands; the California Institute of Technology; Sweden’s Chalmers University of TechnologyChalmers University of Technology is a <span class="st">research-intensive</span> university located in Gothenburg, Sweden that was founded in 1829 following a donation by William Chalmers, a director of the Swedish East India Company. It focuses on technology, science, architecture, and shipping.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>Chalmers University of Technology; Maryland’s Johns Hopkins University; Spain’s University of La Laguna; Sweden’s Lund University; Poland’s Nicolaus Copernicus University; New Jersey’s Princeton UniversityFounded in 1746, Princeton University is a private Ivy League research university in Princeton, New Jersey and the fourth-oldest institution of higher education in the United States. It provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences, and engineering.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>Princeton University; Japan’s Ritsumeikan University; California’s SETI Institute; Maryland’s Space Telescope Science Institute; the University of California, Santa Cruz; the University of California, BerkeleyLocated in Berkeley, California and founded in 1868, University of California, Berkeley is a public research university that also goes by UC Berkeley, Berkeley, California, or Cal. It maintains close relationships with three DOE National Laboratories: Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, and Lawrence Livermore National Laboratory.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>University of California, Berkeley; the University of California, Los Angeles; the University of Hawaii; the University of ChicagoFounded in 1890, the University of Chicago (UChicago, U of C, or Chicago) is a private research university in Chicago, Illinois. Located on a 217-acre campus in Chicago's Hyde Park neighborhood, near Lake Michigan, the school holds top-ten positions in various national and international rankings. UChicago is also well known for its professional schools: Pritzker School of Medicine, Booth School of Business, Law School, School of Social Service Administration, Harris School of Public Policy Studies, Divinity School and the Graham School of Continuing Liberal and Professional Studies, and Pritzker School of Molecular Engineering.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>University of Chicago; the University of Kansas; Indiana’s University of Notre Dame; Australia’s University of Southern Queensland; and Connecticut’s Yale UniversityEstablished in 1701, Yale University is a private Ivy League research university in New Haven, Connecticut. It is the third-oldest institution of higher education in the United States and is organized into fourteen constituent schools: the original undergraduate college, the Yale Graduate School of Arts and Sciences and twelve professional schools. It is named after British East India Company governor Elihu Yale.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>Yale University. Funding was provided by the W.M. Keck Foundation, NASAEstablished in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. Its vision is "To discover and expand knowledge for the benefit of humanity." Its core values are "safety, integrity, teamwork, excellence, and inclusion." NASA conducts research, develops technology and launches missions to explore and study Earth, the solar system, and the universe beyond. It also works to advance the state of knowledge in a wide range of scientific fields, including Earth and space science, planetary science, astrophysics, and heliophysics, and it collaborates with private companies and international partners to achieve its goals.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>NASA and the National Science Foundation.

Signs of life on Earth appeared almost immediately after the formation of our solar system during the Archean period 3.9 billion years ago. Though TOI-1136 is too close to most of its planets to make life likely – the radiation would be too intense – the team hopes that observing this system ultimately answers existential questions about how our planet came to be.

“Are we rare? I’m increasingly convinced our system is highly unusual in the universe. Finding systems so unlike our own makes it increasingly clear how our solar system fits into the broader context of formation around other stars,” said Kane.