Astronomers find a possible explanation for how 'sandwich' planets originate between larger ones

The new method 

The researchers suspect that two original planets in the protoplanetary disc could pave the way to the birth of a smaller one in between them. This alignment is referred to as "sandwiched planet formation" by the authors.

In the official release, the authors go on to explain how this happens. They note that the two initial planets most likely prevent the migration of dust clouds to the inner regions. This, in turn, substantially reduces the amount of dust that accumulates between them. 

And if by any means, the dust in the region clumps, the resultant middle planet will most likely be smaller than the outer two planets. 

“In our study, we propose the rings as sites of planet formation; specifically, there are sandwiched planets currently being formed in those rings. This is very different from the conventional view of planet formation, where we typically expect that the planets form sequentially from the inside to the outside of the disc and get more and more massive further out," explained Farzana Meru, from the Department of Physics at the University of Warwick, in an official release.

Meru further added: "What is also really interesting is that there are examples that we have found from exoplanet observations that actually show this sandwiched planet architecture — where the middle planet is less massive than its neighbors; it is a reasonable proportion of the systems too.”  

More research required 

This theory might also be used to explain the development of smaller worlds in our solar system, such as Mars and Uranus, which depict a similar pattern of small planets surrounded by bigger ones. 

More study is needed to better understand the development of sandwich planets, as per the researchers.  

“The field of planet formation has been revolutionized recently. High-resolution images of planet-forming discs have come out in the last ten years since a new sophisticated telescope (the Atacama Large Millimeter/submillimeter Array) started observing the night sky. These images have given us clues about how planets form and evolve; it’s exciting to be at the forefront of this research,” added Meru.

The study has been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society and will be presented at the National Astronomy Meeting, which started on Monday, July 3.