LP 890-9c might harbor liquid water due to its location in the habitable zone.
Key Takeaways
- Astronomers have discovered two super-Earths orbiting an ultracool dwarf star 100 light-years away.
- One of the planets, LP 890-9c, resides in the star’s habitable zone.
- The inner planet, LP 890-9b, completes its orbit in just 2.7 Earth days.
- The SPECULOOS project, using infrared-sensitive telescopes, confirmed and expanded on TESS’s findings.
- These planets could be studied further for atmospheric signs of life with the James Webb Space Telescope (JWST).
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Two Super-Earths Found Orbiting Ultracool Dwarf Star
An international team of astronomers has discovered two super-Earths orbiting the ultracool dwarf star LP 890-9, located 100 light-years from Earth. The discovery, detailed in a study led by Laetitia Delrez of the University of Liège, is particularly exciting as one of the planets, LP 890-9c, lies within the star’s habitable zone, where conditions may support liquid water.
The two planets differ slightly in size and orbit. LP 890-9b, the inner planet, is 30% larger than Earth and completes an orbit in just 2.7 Earth days. LP 890-9c, the outer planet, is 40% larger and takes 8.5 Earth days to circle its star. Despite their proximity to the dwarf star, the planets’ temperatures are moderated by the star’s relatively low heat output.
Discovery Method and Future Exploration
The discovery began with NASA’s Transiting Exoplanet Survey Satellite (TESS), which identified LP 890-9b as a candidate exoplanet using the transit method—tracking dips in starlight caused by planets passing in front of their stars. The finding was later confirmed by the SPECULOOS project, which uses infrared-sensitive telescopes in Chile and Tenerife to detect planets around cool stars. This method proved vital as TESS is less sensitive to the infrared light emitted by stars like LP 890-9.
During follow-up observations, the SPECULOOS team discovered LP 890-9c, a planet TESS had missed. Michaël Gillon, principal investigator of SPECULOOS, emphasized the significance of these findings, comparing the system to TRAPPIST-1, the coolest known star with orbiting planets. TRAPPIST-1 has become a prime target for studying exoplanet atmospheres, and the LP 890-9 system could follow a similar trajectory.
Future exploration of LP 890-9c will likely involve the James Webb Space Telescope (JWST), which has already demonstrated its ability to detect atmospheric elements like carbon dioxide. Amaury Triaud, a SPECULOOS working group leader, expressed optimism about studying LP 890-9c’s atmosphere to assess its habitability and search for potential biosignatures.
A Broader Perspective on Exoplanet Climates
The discovery of these planets adds to the growing catalog of temperate terrestrial worlds, providing valuable opportunities to study the diversity of exoplanet climates. As Triaud noted, understanding the frequency of biology in the cosmos requires identifying as many such planets as possible. With advanced telescopes and detailed follow-ups, LP 890-9c could offer insights into the conditions that make planets capable of hosting life.
The team’s research was published in the journal Astronomy & Astrophysics.
