// Mayuko Mori, Astrobiology Center
Astronomers used a network of telescopes at the Las Cumbres Observatory to observe the transit of a planet across the disk of its star. In this process, which astronomers call a transit, a temporary decrease in the brightness of the star is observed, allowing the planet to be identified.
From February to March 2024, special cameras MuSCAT3 and MuSCAT4, installed on two-meter telescopes, recorded three transits of TOI-3884b. During the observations, scientists noted unusual changes in the light signal: the planet passed over dark, cold areas of the star known as star spots, similar to sunspots.
Data analysis showed that the temperature of the star spots is 200 degrees lower than that of the rest of the star's surface (3150 K), and they occupy about 15% of the visible area. Small differences in the three observations indicate that these changes are related to the rotation of the star.
To determine the rotation period of the star, the team conducted long-term observations from December 2024 to March 2025, using a network of one-meter telescopes around the world. Astronomers measured the brightness of the star several times a night and established that a complete rotation of the star takes 11.05 days.
By correlating the data on the star's rotation with the movement of the star spots, the researchers reconstructed the three-dimensional structure of the system. The results were unexpected: the planet's orbit is inclined at 62° to the star's equator, which is a significant angle.
Typically, such large inclinations of orbits are explained by gravitational influences from massive planets or neighboring stars in the past of the system. However, no such objects were found in the TOI-3884 system, making it particularly interesting for further study and raising questions about the processes that contributed to the formation of such a unique configuration.
This discovery highlights that the formation and evolution of planetary systems may occur through more complex scenarios than previously thought.
