Research Team Confirms Fifth Exoplanet in Habitable Zone of L 98-59

A research team led by the Trottier Institute for Research on Exoplanets (IREx) at the Université de Montréal has confirmed the existence of a fifth planet in the L 98-59 system, a star located approximately 35 light-years from Earth. This groundbreaking study, which utilized advanced observational techniques and existing data from various telescopes, paints a more complete picture of this compact planetary system, which is notable for its potential to support liquid water and possibly life.

The L 98-59 system previously contained four known planets, three of which were discovered in 2019 through NASA's Transiting Exoplanet Survey Satellite (TESS) and one additional planet identified via radial velocity measurements taken with the European Southern Observatory's ESPRESSO spectrograph. The newly confirmed planet, designated L 98-59 f, exists within the star's habitable zone, where conditions are favorable for liquid water to persist.

According to Charles Cadieux, a researcher at IREx and the study's lead author, the precise measurements yield critical insights into the planetary characteristics of L 98-59. "These new results paint the most complete picture we've ever had of the fascinating L 98-59 system," Cadieux stated. The team employed innovative analysis techniques to enhance the precision of measurements derived from archived data, significantly improving upon previous findings.

The study reveals that the inner planets of L 98-59, particularly L 98-59 b, are likely subject to extreme volcanic activity due to tidal heating, akin to the volcanic moon Io in our own Solar System. Notably, the third planet in the system is characterized as a 'water world,' indicating a significant presence of water, a feature that distinguishes it from planets in our Solar System.

René Doyon, co-author of the study and Professor at the Université de Montréal, emphasized the importance of this system for understanding planetary formation around red dwarf stars. He remarked, "With its diversity of rocky worlds and range of planetary compositions, L 98-59 offers a unique laboratory to address some of the field's most pressing questions."

The meticulous study of the L 98-59 system was possible thanks to the use of data from NASA's TESS and the Very Large Telescope in Chile. The researchers implemented a new line-by-line radial velocity analysis technique, which allowed them to isolate the planetary signals from stellar activity, thus enhancing the accuracy of their findings. Étienne Artigau, another co-author of the study, noted that the team's approach unlocked the potential of previously collected data, revealing insights that had remained hidden until now.

Alexandrine L'Heureux, a Ph.D. student at the Université de Montréal and co-author, expressed excitement about the system's potential for future atmospheric studies, particularly with the James Webb Space Telescope (JWST). "With these new results, L 98-59 joins the select group of nearby, compact planetary systems that we hope to understand in greater detail over the coming years," L'Heureux stated.

The full findings of the research team will be published in the upcoming issue of The Astronomical Journal, and the study represents a significant step forward in exoplanetary research, enhancing our understanding of planetary systems that could harbor life. The implications of this work extend beyond the immediate findings, as it opens new avenues for exploring the diversity of planets in the universe and their potential habitability.