A diminutive red star near Earth is proving to be crucial in the search for rocky planets. Situated merely 35 light-years away, the star L 98-59 contains a collection of exoplanets, including one that could be positioned at the suitable distance for liquid water to exist. Utilizing data from NASA’s TESS space telescope and devices in Chile, researchers from the Université de Montréal have validated the presence of a fifth planet within the system, located in the habitable zone. This planet may receive a level of warmth akin to that of Earth from its star.
The L 98-59 system is recognized for its variety of exoplanets. “With its assortment of rocky worlds and planetary compositions, L 98-59 provides a distinctive laboratory for tackling fundamental questions,” stated researcher René Doyon. “What materials comprise super-Earths and sub-Neptunes? Do planets develop differently around smaller stars? Can rocky planets orbiting red dwarfs maintain atmospheres over extended periods?”
Red dwarf stars, such as L 98-59, or M-type stars, are prevalent in the Milky Way, yet it remains uncertain whether planets orbiting these stars can uphold atmospheres. Néstor Espinoza from the Space Telescope Science Institute remarked that even though these stars are not as hot as the sun, planets in proximity undergo intense stellar radiation. Detecting atmospheres is vital in the quest for habitable worlds. Earth’s atmosphere serves as a “security blanket,” preserving oxygen, blocking ultraviolet radiation, and permitting the presence of liquid water.
Espinoza is at the helm of a James Webb Space Telescope investigation focusing on rocky worlds to assess whether planets around red dwarfs might possess atmospheres. This research will scrutinize a dozen nearby planets over the span of two years. One exoplanet in the L 98-59 system, L 98-59 d, could potentially have a sulfur-rich atmosphere. Researcher Agnibha Banerjee indicated that further observations are necessary to verify this.
The identification of a fifth planet, L 98-59 f, will be detailed in a forthcoming paper in The Astronomical Journal. “These findings provide us with the most comprehensive overview of the L 98-59 system,” remarked Charles Cadieux, the paper’s lead author. “It serves as a robust demonstration of what we can accomplish by integrating data from space telescopes and precise instruments on Earth.”
To locate the planet, scientists applied sophisticated methods to existing data. L 98-59 f does not transit its star from the perspective of Earth, but researchers identified it through the star’s movement influenced by the planet’s gravitational pull. They refined estimates regarding the sizes, masses, and orbits of the other planets. One planet is an unusual “sub-Earth,” while others may be abundant in water or subjected to geothermal heating akin to Jupiter’s moon Io.
Planet hunters feel hopeful about discovering habitable worlds, similar to the TRAPPIST-1 system. “With these fresh findings,” commented coauthor Alexandrine L’Heureux, “L 98-59 enters the exclusive category of nearby, compact planetary systems we aspire to examine in detail in the upcoming years.”