The newly discovered planet has a mass equivalent of eight Earths and orbits very close to a larger planet, the hot gas giant TOI-1408b. Scientists were puzzled when they started looking closely at the two two planets and its star TOI-1408. The small planet has a peculiar way of moving in its orbit. The interactions between the two planets and its star can be likened to a rhythmic dance.
- The small planet has very unusual behaviour in its orbit, showing large variations in the timing of when it passes in front of its star, which we don't usually see. The existence of the small planet challenges existing theories about the formation and stability of planetary systems,’ says Judith Korth, an astrophysicist at Lund University who led the work.
Providing important keys
The new study, published in the scientific journal The Astrophysical Journal Letters, shows that planetary systems may be significantly more complex than scientists previously thought. The discovery of a small planet between a star and a large gas giant is rare and offers a unique case study for the evolution of planetary systems. This can help scientists understand more about how planets form in other solar systems.
- ‘Our results will help scientists learn more about how planets form and how they behave when they are very close to each other, especially in systems with giant planets,’ says Judith Korth.
Exoplanet hunters
Exoplanets are planets located in solar systems other than our own. The first confirmed discovery was made in 1995. Since then, 5 747 exoplanets have been recorded. The discovery of the interstellar oddity TOI-1408c was made with the help of NASA's Transiting Exoplanet Survey Satellite (TESS). Since its launch in 2018, it has observed over 7 000 potential exoplanets.
- I hope that our results can be used in future studies to discover even more planets in other systems. But also to better understand the wide range of planetary systems that exist in our amazing galaxy,’ says Judith Korth.
In addition to Lund University, some 50 universities and organisations have participated in the work.
The study ‘TOI-1408: Discovery and Photodynamical Modelling of a Small Inner Companion to a Hot Jupiter Revealed by Transit Timing Variations’ is published in The Astrophysical Journal Letters.