Thursday 25 September 2025
A peculiar planet has been discovered orbiting a small, cool star called TOI-3884. This exoplanet, dubbed TOI-3884 b, is unlike any other known to date. Its unusual behavior has led scientists to uncover secrets about the starspot configuration of its host star and the alignment of its own rotation.
The transit shape of TOI-3884 b appears chromatic and asymmetric due to persistent starspot crossings. In simple terms, when the planet passes in front of the star, it covers different regions with varying levels of brightness. This phenomenon is only possible if the star’s rotational axis is tilted along our line of sight, indicating that the planet-occulted starspot is located near the stellar pole.
To better understand this unusual system, researchers acquired photometric transits over a period of three years using the Swiss 1.2-meter Euler telescope. By analyzing these data, they found that the transit shape changes over time, with no two observations matching perfectly. This variability is not due to changes in temperature or size of the starspot but rather because of a slight misalignment between the spot center and the stellar pole.
The scientists also precisely measured the sky-projected spin-orbit angle of 37.3 degrees and the true spin-orbit angle of 54.3 degrees. These measurements will be crucial for understanding the formation and evolution of close-in, massive planets around fully convective stars like TOI-3884.
The discovery of TOI-3884 b has shed light on the complex dynamics between a star and its planetary companion. The alignment of their rotational axes plays a significant role in shaping the transit shape and influencing the planet’s atmospheric properties. This finding has important implications for future studies of exoplanetary systems and the search for life beyond Earth.
The team used a sophisticated statistical model to analyze the data, accounting for various factors that could affect the transit shape. They also employed a technique called PyTranSpot to simulate the spot configuration on the star’s surface. By combining these approaches, they were able to accurately reconstruct the starspot pattern and its evolution over time.
The study of TOI-3884 b is an excellent example of how scientists can use innovative methods to unravel the mysteries of exoplanetary systems. As our understanding of these complex systems grows, we may uncover new insights into the potential for life beyond Earth.
Cite this article: “Mysterious Exoplanet Reveals Secrets of Star’s Rotational Dynamics”, The Science Archive, 2025.
Exoplanet, Starspot, Chromatic, Asymmetric, Transit, Euler Telescope, Spin-Orbit Angle, Photometric Transits, Convective Stars, Pytranspot
