Dancing Planets
Six exoplanets orbit a star around 100 light-years away in perfect synchrony
Scientists have discovered a rare star system located about 100 light years away (which is actually relatively close, as far as space goes) from us, with six planets orbiting their central star in a rhythmic beat. According to the study, the planets move in such perfect harmony that it can be compared to dancing and set to music!
The newly discovered planets orbit a star known as HD 10067 in the constellation Coma Berenices, near Virgo in the northern sky. The star itself, which is similar in type to that of the Sun, but smaller and cooler, has been known for some time. However, the recent detection of its orbiting exoplanets was the result of data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and the European Space Agency’s (ESA) Characterising Exoplanet Satellite (CHEOPS).
Each of the exoplanets found was characterized as sub-Neptunes, meaning their radii were between the Earth’s and Neptune’s. This classification as sub-Neptunes is important because planets that are like Neptune or even larger are rare because much more gas is needed during the planetary formation process.
The fact that these newly discovered exoplanets were sub-Neptunes did not come as a surprise since after all, more than half of all Sun-like stars have such planets orbiting them. However, despite the fact that these planets are so common, scientists know very little about them. The detection of the new star system with its dancing planets may change that. UChicago scientist Dr. Rafael Luque, who led the study, noted in his statement:
“The discovery is going to become a benchmark system to study how sub-Neptunes, the most common type of planets outside the solar system, form, evolve, what they are made of, and if they possess the right conditions to support the existence of liquid water in their surfaces”.
When planetary systems form, the planets around stars tend to form in resonance with each other. This means that most star systems at first tend to have synchronized orbits. However, this synchronicity between planets can be easily disturbed. For example, a close encounter with a passing star, an asteroid impact event can all disrupt the careful balance.
According to Dr. Luque, only about 1 percent of all planetary systems remain in resonance, locked in their endless dance. Many of the multi-planet systems known to astronomers are not in resonance but look close enough that they could have been in resonance before. However, the six planets orbiting HD110067 have managed to stay in perfect synchronicity with each other: The planet closest to HD110067 makes three orbits for every two of the next planet - called a 3/2 resonance - and this pattern is repeated among the four innermost planets in the system. For the two outer planets, the resonance changes slightly to a 4/3 resonance which means that the inner planet orbits four times for every three of the last planet.
And these resonant orbits are rock-solid. Scientists have come to the conclusion that the six planets have been performing this same rhythmic dance around HD110067 since the system formed billions of years ago. But what does the discovery tell us about these exoplanets themselves? The composition of sub-Neptunes is a major source of interest because many of them could be rocky worlds like our Earth and could have liquid water on their surfaces.
Over the coming months, more precise measurements of these planets’ masses and orbits will be needed and tools such as NASA’s James Webb Space Telescope are well equipped with the necessary instruments to study their atmospheric composition.
To read our article with more detailed information about the James Webb Space Telescope, click on this link.
Sources:
"Scientists Discover Rare 6-Planet System that Moves in Strange Synchrony." University of Chicago News, 2021, news.uchicago.edu/story/scientists-discover-rare-6-planet-system-moves-strange-synchrony.
"Astronomers Stunned by Six-Planet System Frozen in Time." Science, 2021, www.science.org/content/article/astronomers-stunned-six-planet-system-frozen-time.
"Six-Planet System in Perfect Harmony Shocks Scientists." Scientific American, 2021, www.scientificamerican.com/article/six-planet-system-in-perfect-harmony-shocks-scientists.
"Discovery of Six Planets Solar System with Synchronized Dance." Star Gazer Daily, 2021, stargazerdaily.com/discovery-of-six-planets-solar-system-with-synchronized-dance.
"NASA Satellites Discovered a 6-Planet Solar System in Perfect Synchrony." PBS NewsHour, 2021, www.pbs.org/newshour/science/nasa-satellites-discovered-a-6-planet-solar-system-in-perfect-synchrony.
