Astronomers Discover Massive Exoplanet in Great Bear Constellation Orbiting Star

Astronomers from the Nicolaus Copernicus University Institute of Astronomy have discovered a new planet in the constellation of the Great Bear, orbiting a star similar to the Sun. The planet is massive, with an orbital period of several years, and its discovery sheds light on the formation and evolution of planetary systems. Led by Professors Gracjan Maciejewski and Andrzej Niedzielski, the research team used Doppler observations from the Hobby-Eberly Telescope in Texas and the Italian Galileo telescope in the Canary Islands to track the object’s movement.

The team also included Julia Sierzputowska, a student of astronomy, who analyzed photometric observations obtained with the Transiting Exoplanet Survey Satellite space telescope. The discovery provides insight into hierarchical planetary systems, where one planet forms a tight pair with its star and a second planet orbits the pair in a wider orbit. This peculiar configuration is stabilized by effects arising from the general theory of relativity, as shown by Professor Krzysztof Goździewski’s detailed numerical studies. The research has implications for our understanding of planetary formation and evolution, and may lead to further discoveries in the field.

The journey began nearly 20 years ago, when astronomers first detected a massive planet orbiting HD 118203. However, Doppler observations hinted at the presence of another planet in the system. Prof. Andrzej Niedzielski and his team embarked on an observational quest to uncover the truth.

Using some of the world’s most powerful telescopes, including the Hobby-Eberly Telescope in Texas and the Galileo telescope in the Canary Islands, the researchers collected data over eight years. Yet, it wasn’t until another seven years had passed that they finally obtained conclusive evidence of a second planet.

The breakthrough came when Dr. habil. Gracjan Maciejewski and his team analyzed new observations from March 2023, which allowed them to determine the planet’s orbital parameters and mass. By combining Doppler and astrometric measurements, they built a complete model of the planetary system and studied its dynamical behavior.

But that wasn’t all – Julia Sierzputowska, an astronomy student at NCU, played a crucial role in ensuring there were no other hidden planets in the system by analyzing photometric observations from the Transiting Exoplanet Survey Satellite space telescope.

The discovery revealed a peculiar hierarchical planetary system, where one planet forms a tight pair with its star, and a second planet orbits the pair in a wider orbit. Prof. Krzysztof Goździewski’s numerical studies showed that despite their massive sizes and elongated orbits, the planets’ mutual gravitational influence doesn’t destabilize the system over millions of years – thanks to effects arising from general relativity.

This finding has significant implications for our understanding of planetary formation and evolution. Hierarchical systems like HD 118203 offer a unique window into the mysteries of massive planet formation. As Prof. Maciejewski notes, “Learning about systems with massive gaseous planets seems important so that we can get to know our nearest, astronomical backyard.”