Hot Jupiters Can Co-Exist with Other Planets
Published on: January 22, 2025 by Mark Thompson
Introduction
Exoplanets come in a variety of forms, and one particular type, the Hot Jupiters, have recently captured the attention of astronomers. These gas giants are typically found orbiting extremely close to their host star, completing an orbit in a mere few days or even hours. Traditionally, it was believed that these unique planets migrated from further out in the system, often pushing aside or ejecting other planets in the process. This understanding painted a picture of a potentially violent evolutionary path for Hot Jupiters. However, recent studies suggest a far less aggressive picture, as new observations reveal the existence of a Hot Jupiter in a multi-planetary system alongside a Super-Earth and an icy giant.
Understanding Hot Jupiters
Hot Jupiters are a class of exoplanets that, as the name suggests, are similar in some ways to Jupiter, our solar system’s largest planet. They are, however, defined by their extreme proximity to their host stars and their resultant high temperatures. Where Jupiter takes around 12 years to complete a full orbit around the Sun, Hot Jupiters can complete an orbit in just a few days.
The intense levels of radiation and heating from their host stars can cause temperatures in their upper atmospheres to soar above 1,000°C, with some Hot Jupiters expanding significantly due to the heat. This swelling is often beyond what would be expected for gas giants, revealing a degree of atmospheric response to solar insolation that is of great interest to scientists.
Formation Theories of Hot Jupiters
Current models of planetary formation suggest that inner planets are primarily composed of denser materials, while lighter, gas giant compositions are found further out in the protoplanetary disk. The presence of gas giants like Hot Jupiters in close orbits contradicts these models. The prevailing theory has been that they form further out and migrate inward as the solar system evolves, but this raises important questions about the fate of any other planets in their path.
New Discoveries Challenge Previous Understandings
As recent studies have pointed out, the traditional view of Hot Jupiters being solitary in their orbit—ejecting or consuming other potentially habitable planets—has been challenged. A research team from the Astronomy Department of the UNIGE Faculty of Science, in partnership with several organizations like UNIBE and UZH, made a significant discovery with the identification of a multiple planetary system containing a Hot Jupiter, a Super-Earth within a closer orbit, and another gas giant further out. This discovery hints at the possibility of a revised migration model that allows more than one type of planet to coexist within a single system safely.
The WASP-132 System
Using detailed photometric measurements of the WASP-132 system, located over 400 light years away, scientists observed that WASP-132b (the Hot Jupiter in question) has a mass approximately 0.41 times that of Jupiter, with an orbital period of just 7.1 days. Additional measurements from the HARPS spectrograph at the La Silla Observatory in 2022 confirmed the presence of a Super-Earth in this system, with a mass around six times that of Earth. Researchers are continuing to refine their measurements and utilize satellites like Gaia to pinpoint the positions and orbits of these planets more accurately.
Implications of the Discovery
This finding is vital as it signals that current models of planetary migration, which enable gas giants to occupy their positions, may not be comprehensive. This suggests a “cool” migration path that allows for coexistence among various planets without undue violence or ejection of neighbors. Researchers continue to refine the models that outline how planets evolve and interact within a system, which may lead to new insights into the origins of planetary systems.
Conclusion
As the research continues and the analysis of the WASP-132 system progresses, the insights gained will help shape the future understanding of planetary migration and formation models. The coexistence of Hot Jupiters with Super-Earths and other gas giants opens new discussions about the variety and dynamics of planetary systems, challenging previously held notions about how planets behave and thrive in the cosmic landscape.
Source: Not all Hot Jupiters orbit solo
