If you're Diego Munoz, an assistant professor in Northern Arizona University's Department of Astronomy and Planetary Science, the answer is simple: You get to work on new models.
With support from the National Science Foundation and his co-primary investigators at Indiana University Bloomington, Munoz will head a three-year investigation into the formation of eccentric warm Jupiters - gas giant planets that exist outside our solar system and have peculiar and sometimes unprecedented oval-shaped orbits.
By the end of the study in 2028, Munoz hopes to theoretically understand not only how these planetary outliers formed, but also if and how these astrophysical processes could have influenced the creation of our solar system.
"The variability of extrasolar planets is just enormous," Munoz said. "Extrasolar systems can look like our solar system, but in some cases, they look entirely different and exotic. We're very interested in seeing how the solar system forms in context by understanding systems that look like ours and ones that look completely different. We can get a sense of what the extremes are, how average our planet formation history is and how average our solar system is."
Some of the most interesting extreme systems, Munoz said, are those that house eccentric warm Jupiters.
Scientists previously believed warm Jupiters could form like their well-studied hot Jupiter cousins, which have similar masses and sizes but are closer to their host stars. However, as telescopes became more advanced and data grew more precise, astronomers discovered warm Jupiters may have complex origins of their own.
While hot Jupiters can orbit their stars in almost any orientation, warm Jupiters are almost universally aligned with their hosts' equators. Data also suggest that the more eccentric, or oval-shaped, a warm Jupiter's orbit, the more aligned it is with its star, a phenomenon no existing model of planet formation could have predicted.
Munoz hopes to change that by building a small but growing sample of eccentric warm Jupiters using NASA's Transiting Exoplanet Survey Satellite and basing new models and existing model updates on what he finds.
"The data tells us that warm Jupiters are not just the tail end of hot Jupiters," Munoz said. "It tells us they may have a different history. We need to understand if this is just a quirk - if these are pathological cases that happen maybe once every million cases - or if there is an additional physical process that we have ignored in the past that we might be able to unveil."
Knowing what processes are at work during an eccentric warm Jupiter's formation could help astronomers uncover hidden truths about our solar system's evolution and the creation of countless others just like it. But before diving into the implications, Munoz has to interrogate multiple hypotheses until he can find one that is practical and plausible.
One possibility is that these eccentric warm Jupiters have companion planets that somehow alter their orbits without misaligning them relative to their stars' equator. Having varying eccentricities and varying inclinations simultaneously is well understood from a modeling perspective, but having one and not the other is not as easily explained.
Another concerns the gaseous nebulas in which the planets and their stars formed. Munoz reasons that these planets could have interacted with their surroundings in ways astronomers could never have anticipated as they were developing. Discoveries of this nature could permanently change the way astronomers map planet formation.
Last, and Munoz's favorite, is the idea that the stars in these systems are responsible. Because stars are fluid bodies, they can develop internal waves that can sometimes crash and extract energy from a planet's orbit in peculiar ways. He said it's mathematically feasible that these waves could also be the reason warm Jupiters align so closely with their host stars' equators.
The answer to which theory is correct, as of now, is a mystery, but it's one Munoz will be hard at work solving with myriad modeling techniques.
"I'm a theorist, so I work on models using heavy-duty computers, pencil-and-paper calculations and anything in between," Munoz said. "We don't have a model that predicted this to begin with, so we're going to go crazy and dive into the most creative ways we can think about this problem. But once you have a mathematical model, that is just the beginning."
Next year, Munoz will hire a graduate student who excels in creative puzzle solving to assist him throughout his modeling study. In the meantime, he said his research into his host star hypothesis has been promising, and he hopes to publish his findings in the near future.
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