Refined mass and radius measurements for planets orbiting stars TOI-4438 and TOI-442

Star system: G 182-34 | Distance from the Sun: 98.1 light years

Researchers have completed a detailed re-analysis of two planetary systems, TOI-4438 and TOI-442, providing more precise physical data for their orbiting planets. By combining new transit observations from the TESS space telescope with high-resolution infrared spectroscopy, the study clarifies the properties of these worlds. The analysis also investigated the magnetic activity of the host stars, which are both Red dwarf stars, to improve the accuracy of the planetary models.

For the planet orbiting the Red dwarf TOI-4438, the team refined its mass to approximately 4.11 Earth masses and its radius to 2.40 Earth radii. Similarly, the planet orbiting the Red dwarf TOI-442 was found to have a mass of 28.38 Earth masses and a radius of 4.25 Earth radii. These measurements represent a significant increase in precision compared to previous studies, helping scientists better understand these specific systems.

To achieve these results, the team used the radial velocity method, which detects the tiny gravitational tugs planets exert on their host stars. By accounting for the stars' own surface magnetic activity, characterized by observing Zeeman signatures—a splitting of spectral lines caused by magnetic fields—the team reduced interference and refined the orbital data. No further planets were confirmed in either system, though a single-transit event was noted in the TOI-4438 data.

Key findings
- The planet around TOI-4438 has a mass of 4.11 Earth masses and a radius of 2.40 Earth radii.
- The planet around TOI-442 has a mass of 28.38 Earth masses and a radius of 4.25 Earth radii.
- Both systems were analyzed using new data from the TESS telescope and the SPIRou infrared instrument.
- Researchers detected persistent magnetic activity on TOI-442 and intermittent activity on TOI-4438.
- Improved mathematical models accounting for stellar variability provided more reliable planetary parameters.

Scientific study

Revisiting TOI-4438 and TOI-442 planetary systems with new observations from SPIRou and TESS (external link)