By: Maxim Basu


Photo Credits: Detlev Van Ravenswaay/Science Photo Library

Jupiter. It’s the biggest planet in our solar system, the one with the beauty mark, the “Great Red Spot.” You will have learned a little about it growing up, and definitely if you have ever taken astronomy at U of T, be it as a breadth requirement with Dr. Michael Reid or otherwise. 

Recently, researchers Chelsea Huang, Yanqin Wu, and Amaury Triaud from the Astronomy department have discovered that Warm Jupiters in other solar systems are sometimes surrounded by companion planet-like matter. 

Unless you’ve taken AST101 or AST201, that might not make much sense. To explain, the term “Warm Jupiter” is used by astronomers as a part of a classification system created to view planets in other solar systems. Astronomers scale down planets in other solar systems to the size of planets in our solar system, which helps them envision the sizes of the planets. For instance, a Mercury-like planet would be the size of Mercury, and a Jupiter-like planet would be the size of Jupiter. 

A Hot Jupiter is a planet the size of Jupiter that is positioned really close to its star—on our scale, it would be positioned at Mercury’s orbital. It would literally be on fire. A Warm Jupiter is a planet that is the size of Jupiter but orbits its star a bit further away from where a Hot Jupiter would be—on our scale, it would be positioned roughly at Earth’s orbital. The importance of positioning in this system of classification makes Warm Jupiters a fascinating phenomenon to study how orbits and temperature are influenced. 

​Out of 27 Warm Jupiters examined by the researchers, they found that 11 had companion planets. In the study, Hot Jupiters had no companions whatsoever. This was unsurprising news, because at those distances, very little matter exists. 

The discovery that Warm Jupiters have companion planet-like matter orbiting with them is important because it challenges a major theory in the astronomical community. Traditionally, it has been thought that Warm Jupiters are loners and that they continually orbit their stars (which are similar to our Sun) solo.  

Now we know that Warm Jupiters aren’t like U of T students (weirdly and utterly alone), and U of T has been placed on the academic map yet again alongside discoveries like that of insulin and all those others that the “Boundless” posters around campus boast about. 

​This discovery has added complexity to our understanding of Warm Jupiters by creating definite categories for them: Warm Jupiters that have companion planets travelling around them and Warm Jupiters that do not. This new classification has led researchers to contemplate fascinating theories about the origins of Warm Jupiters. Huang, a member of the research team, stated, “Our findings suggest that a big fraction of Warm Jupiters cannot have migrated to their current positions dynamically and that it would be a good idea to consider more seriously that they formed where we find them.”

These are fighting words, considering that although the researchers agree that the “origin of [Warm] Jupiters … has remained an unsolved issue,” it has traditionally been thought that Warm Jupiters could not have possibly originated where they orbit their stars because there is simply not enough matter to form them near their stars. You cannot create something from nothing. 

People like Huang have found an alternative explanation; they believe that Warm Jupiters gravitate towards their current locations from the deep depths of the cosmos. Furthermore, it is likely that Warm Jupiters have not finished moving towards their stars; due to their mass, they are able to overpower the forces of gravity that keep smaller planets in orbit and it is very likely that Warm Jupiters continue travelling towards their stars, and with enough time, become Hot Jupiters. 

The future is looking bright for Huang and for the research team. They are all highly optimistic about finding more Warm Jupiters with companions. Huang has pledged that the research is going to continue. Moreover, she concluded that “when we take into account that there is more analysis to come, … the number of Warm Jupiters with smaller neighbours may be even higher. We may find that more than half have companions.”

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