The two largest planets of the solar system, Jupiter and Saturn, received world publicity on December 21, 2020, because they slid closer than they have been since 1623. “Visible around the world, the” Great Conjunction “placed the two planets only 0.1 degrees apart.
It is typically known that Jupiter and Saturn “keep their distance” from each other. Understanding why these two planets have so much space between them has been the focus of a recent study Icarus journal article. Born Eccentric: Limitations in Jupiter’s and Saturn’s pre-instability orbits included analysis of supercomputer simulations by an international team of researchers – thanks to the National Science Foundation’s (NSF) Extreme Science and Engineering Discovery Environment (XSEDE).
Comet, a supercomputer at the San Diego Supercomputer Center at UC San Diego, and Bridges at the Pittsburgh Supercomputing Center, more than 6,000 simulations were used to better understand the space between the two planets. The development and analysis of the simulations was led by the Carnegie Institute in Washington, DC, postdoctoral fellow Matthew Clement, who teamed up with astronomer Sean Raymond of the Astrophysique de Bordeaux Laboratory in Pessac, France, and several researchers from the University of Oklahoma, Rice University and Southwest Research Institute.
“We are pretty sure that giant planets, including Jupiter and Saturn, were born closer than they are today, and one of the challenges to determine how and why they are so far away now is to better understand how Jupiter’s orbit has become so eccentric and elliptical,” he said. Clement. “Historically, simulations that reproduce Jupiter’s orbital shape tend to push Saturn too far toward the outer solar system, away from where Uranus is today, so we used the initial conditions in our study according to hydrodynamic models of giant planets forming in gaseous proto-planetary disks to more consistently generate orbits similar to Jupiter and Saturn. “
According to scientists, the interaction of the orbits of these two gas giants drives a good amount of evolution of the solar system as a whole. Jupiter itself makes up about two-thirds of the total mass of planets, asteroids and comets in the solar system. Meanwhile, Saturn makes up most of the rest of the material.
“The orbital dance performed by Jupiter and Saturn today triggers countless dynamic effects in the solar system and has probably influenced the growth of the Earth in the past,” Clement explained. “This helps us understand why Earth is a beautifully temperate and water-rich place to live, while Mars and Venus are quite inhospitable to life as we know it.”
Although previous studies have assumed that Jupiter and Saturn were born in what is known as the 3: 2 resonance of the mean motion (Jupiter orbited the Sun three times in every two Saturn cycles), Clement’s research considers the initial resonance to be 2: 1. each of Saturn). So the planets formed further.
“This is the best way to explain the modern orbital dance of the planet,” he said. “Interestingly, perhaps the best-observed photo-planetary disk, known as PDS-70, a system of planets in the process of growth, appears to be dominated by two giant planets similar to Jupiter and Saturn in our own solar system: 1 resonance. “
Understanding Jupiter and Saturn in this way also helps planetary scientists compare our own planetary system to a large contingent of discovered exoplanets. Clement said that if we looked at our current solar system from afar with current techniques, we could only discover Jupiter and Saturn – not any other planet. However, when we look at the population of planets that have so far been discovered with masses similar to the masses of Jupiter and Saturn, their orbits do not look at all like those in the solar system.
Some systems host Jupiter-like planets in very short orbits, closer to the sun than Mercury (so-called hot Jupiters). Other planets are similar to Jupiter and Saturn in more distant orbits like those on real Jupiter and Saturn). However, their orbital eccentricities are extremely high, like comets in our solar system. There are also several systems with four or more giant planets in the wide orbits of low eccentricity that our giant planets have, but they are in a resonance chain. Thus, according to researchers, the solar system exists in an unusual “middle ground” between the last two types of systems.
Our work essentially tries to understand why we seem to be the “missing link” between these two types of systems, and our results show that this is due to Jupiter and Saturn resonating 2: 1, and not because of a more compact chain like 3: 2. Said Clement. “Since this is such a chaotic process, we could not take our project to this level of a thousand simulations without Comet i Bridges.”
Key funds for this research were provided by the National Science Foundation (AST-1615975), the NSF CAREER Award (1846388), NASA’s Astrobiological Institute (NNH12ZDA002C and NNA13AA93A), and NASA (80NSSC18K0828). Calculation time included Comet i Bridges was assigned via XSEDE (TG-AST200004).