Title: New Exoplanet Discovery Enhances Understanding of Planet Formation
Date: August 4, 2023
An international team of scientists has made an intriguing discovery involving an unusually large Jupiter-sized planet orbiting a low-mass star named TOI-4860 in the Corvus constellation. This remarkable find challenges existing assumptions about planet formation and provides valuable insights into the process.
The gas giant, referred to as TOI-4860 b, stands out for two key reasons. Firstly, stars with low mass like TOI-4860 are not typically expected to host planets as massive as Jupiter. Secondly, the planet displays a significant enrichment of heavy elements, making it distinct from other known gas giants.
Led by astronomers from the University of Birmingham, the study was detailed in a letter published in the Monthly Notices of the Royal Astronomical Society. The initial identification of the planet was made using NASA’s Transiting Exoplanet Survey Satellite, which detected a drop in brightness as TOI-4860 b transited in front of its host star. However, additional data was required for confirmation.
To validate their findings, the team utilized the SPECULOOS South Observatory in Chile’s Atacama Desert. They measured the planetary signal across several wavelengths and observed the planet before and after it disappeared behind its host star. Notably, no change in light was observed during these phases, indicating that the planet was not emitting any light. The researchers also collaborated with a Japanese group using the Subaru Telescope in Hawai’i to accurately measure the mass of the planet, effectively confirming its existence.
The discovery of TOI-4860 b was driven by a group of Ph.D. students involved in the SPECULOOS project. Their initiative to study this star system and confirm the presence of the planet has yielded valuable results. The researchers discovered that the canonical planet formation model, which links planet formation to the mass of the star’s disk, does not fully explain the existence of high-mass planets around low-mass stars. TOI-4860 b’s presence challenges this model.
Amaury Triaud, Professor of Exoplanetology at the University of Birmingham, expressed gratitude for the efforts of the Ph.D. students in proposing the observation of systems like TOI-4860. He emphasized that studying planets with these unique characteristics deepens our understanding of planet formation. Triaud noted that the planet’s enrichment in heavy elements, along with similar findings in its host star, suggests that an abundance of heavy elements played a crucial role in catalyzing the planet formation process.
TOI-4860 b takes a mere 1.52 days to complete a full orbit around its host star. Due to its host being a cold, low-mass star, the planet is classified as a “warm Jupiter” – a subclass of gas giants that hold significant interest for astronomers. The team plans to utilize telescope time at the Very Large Telescope in Chile to confirm the presence of several more planets with similar properties.
Mathilde Timmermans, a student involved in the SPECULOOS project at the University of Liege in Belgium, highlighted that TOI-4860 b’s short orbital period and its host star’s properties present an excellent opportunity to study the planet’s atmospheric properties and gain insights into gas giant formation.
The recent discovery broadens our understanding of planet formation and has the potential to unravel more mysteries as scientists delve deeper into the unique characteristics of such exoplanets.
Reference:
Amaury Triaud et al, An M-dwarf accompanied by a close-in giant orbiter, Monthly Notices of the Royal Astronomical Society (2023). DOI: 10.1093/mnrasl/slad097