Scientists from the University of Warwick have unveiled an innovative process of planet formation within the protoplanetary disc—a region composed of swirling dust and gas surrounding a central star. Termed “sandwiched planet formation,” this method suggests that the presence of two sizable planets within a protoplanetary disc can give rise to the emergence of a smaller planet situated between them. This phenomenon occurs due to the obstructive influence exerted by the larger planets, impeding the inward flow of dust and leading to the accumulation of less dust between them. Eventually, this accumulated dust can coalesce to form a smaller planet, creating a sandwich-like arrangement with the two larger planets. (Image shows the formation of a planet between two large planets.) Credit: Dr. Mark Garlick/University of Warwick
Researchers at the University of Warwick have proposed a novel mechanism for the formation of planets known as “sandwiched planet formation.” According to this theory, smaller planets can originate between two larger planets within a protoplanetary disc. This discovery may provide insights into the formation of planets such as Mars and Uranus, which are relatively smaller and are surrounded by larger planets.
Scientists have recently made a significant breakthrough in understanding the formation of small planets.
The team at the University of Warwick focused their investigation on the protoplanetary disc—an environment comprising gas and dust that encircles a central star—known as the “birth environment” of planets.
Their research revealed a previously unexplored method of planet formation within this region. The findings have been submitted for publication in the Monthly Notices of the Royal Astronomical Society and are being presented at the National Astronomy Meeting, commencing on Monday, July 3. The researchers demonstrated how the presence of two large planets within the protoplanetary disc can potentially give rise to a smaller planet situated between them, which they refer to as “sandwiched planet formation.”
This occurrence arises from the fact that the two larger planets impede the inward flow of dust. Consequently, the amount of dust accumulating between them is significantly reduced compared to a scenario without an outer planet. If this dust were to gradually coalesce into a planet, the resulting middle planet would likely be smaller than the outer two planets, akin to the filling of a sandwich.
Although further research is necessary to fully comprehend this phenomenon, this theory offers a plausible explanation for the formation of small planets like Mars and Uranus, each surrounded by larger neighboring planets.
Associate Professor and Dorothy Hodgkin Fellow, Farzana Meru, from the Department of Physics at the University of Warwick, remarked, “In the past decade, observations have revealed the presence of rings and gaps in protoplanetary discs. These gaps are indicative of potential planet locations, and theoretical studies have shown that planets cause dust rings to form just outside their orbits. Understanding the dynamics within these rings is an important question for astronomers worldwide.”
“In our study, we propose that these rings serve as sites for planet formation, specifically suggesting that sandwiched planets are currently forming within them. This challenges the conventional view of planet formation, which assumes a sequential formation from the inner to the outer regions of the disc, with increasing mass further out. Furthermore, we have discovered examples from exoplanet observations that support this sandwiched planet architecture, where the middle planet possesses less mass than its neighbors and forms a significant portion of the system.”
“The field of planet formation has undergone a revolution in recent years. With the advent of high-resolution images of planet-forming discs captured by the Atacama Large Millimeter/submillimeter Array, a state-of-the-art telescope, we have gained valuable insights into the processes of planet formation and evolution. It is truly exciting to be at the forefront of this research.”
The study, funded by The
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Frequently Asked Questions (FAQs) about planet formation
What is sandwiched planet formation?
Sandwiched planet formation is a newly proposed method of planet formation within protoplanetary discs. It suggests that the presence of two larger planets in the disc can lead to the formation of a smaller planet between them. The obstruction caused by the larger planets hinders the inward flow of dust, resulting in the accumulation of less dust between them. Over time, the gathered dust can come together to form a smaller planet, creating a sandwich-like arrangement.
How does sandwiched planet formation explain the formation of smaller planets?
Sandwiched planet formation offers an explanation for the birth of smaller planets like Mars and Uranus. According to this theory, the presence of two larger planets restricts the amount of dust accumulating between them, which ultimately leads to the formation of a smaller planet. This phenomenon helps to account for the observed architecture of systems where smaller planets exist alongside larger neighboring planets.
What evidence supports sandwiched planet formation?
High-resolution images of planet-forming discs obtained by telescopes like the Atacama Large Millimeter/submillimeter Array have provided valuable insights. These images have revealed the presence of rings and gaps in protoplanetary discs, indicating potential locations for planet formation. Additionally, observations of exoplanets have shown examples of the sandwiched planet architecture, where the middle planet is less massive than its neighbors. These findings support the concept of sandwiched planet formation.
How does sandwiched planet formation challenge conventional views of planet formation?
Sandwiched planet formation challenges the traditional sequential model of planet formation, which assumes that planets form from the inside to the outside of the protoplanetary disc and grow more massive further out. In contrast, sandwiched planet formation suggests that planets can form in the rings of dust created just outside the orbits of larger planets. This new understanding expands our knowledge of planet formation processes and highlights the dynamic nature of protoplanetary discs.
More about planet formation
- University of Warwick: University of Warwick – Department of Physics
- Monthly Notices of the Royal Astronomical Society: Monthly Notices of the Royal Astronomical Society
- National Astronomy Meeting: National Astronomy Meeting
- Atacama Large Millimeter/submillimeter Array (ALMA): Atacama Large Millimeter/submillimeter Array
