![]() The best fit they found: a fifth planet with a 41-day orbit, and a sixth just shy of 55.Īt this point the science team almost hit a dead end. The scientists again ran through the list of possible orbits if there were two additional, outer planets that fit the expected chain of resonances across the whole system. Two more transits had been seen, but their orbits remained unaccounted for because they were only single observations (more than one transit observation is needed to pin down a planet’s orbit). The only resonance chain that matched up suggested a fourth planet in the system, with an orbit about 31 days long. The science team, led by Rafael Luque of the University of Chicago, worked through a well-known list of resonances that potentially could be found in such systems, trying to match them to the remaining transits that had been picked up by TESS. The next steps were all about math and gravity. The three planets’ orbits matched what would be expected if they were locked in a 3/2 resonance. Then the scientists noticed something extraordinary. A third planet, with a year about 20 days long, was identified with the help of data from CHEOPS, The European Space Agency’s CHaracterising ExOPlanets Satellite. ![]() But it was difficult to distinguish how many planets they represented, or to pin down their orbits.Įventually, astronomers singled out the two innermost planets, with orbital periods – “years” – of 9 days for the closest planet, 14 days for the next one out. ![]() Combining the TESS measurements, made in separate observations two years apart, revealed an assortment of transits for the host star, called HD 110067. The first hints of it came from NASA’s TESS (the Transiting Exoplanet Survey Satellite), which tracks the tiny eclipses – the “transits” – that planets make as they cross the faces of their stars. More precise measurements of these planets’ masses and orbits will be needed to further sharpen the picture of how the system formed.įun facts: The discovery of this system is something of a detective story. Its rigid stability was locked in early the planets’ 3/2 and 4/3 resonances are almost exactly as they were at the time of formation. And that, in turn, could say something important about how this system formed. Such reliable stability means this system has not suffered the shocks and shakeups scientists might typically expect in the early days of planet formation – smash-ups and collisions, mergers and breakups as planets jockey for position. And these resonant orbits are rock-solid: The planets likely have been performing this same rhythmic dance since the system formed billions of years ago. In this case, the planet closest to the star makes three orbits for every two of the next planet out – called a 3/2 resonance – a pattern that is repeated among the four closest planets.Īmong the outermost planets, a pattern of four orbits for every three of the next planet out (a 4/3 resonance) is repeated twice. Discovery Alert: Webb Maps and Finds Traces of Water in an Ultra-hot Gas Giant's Atmosphereĭetails: While multi-planet systems are common in our galaxy, those in a tight gravitational formation known as “resonance” are observed by astronomers far less often.
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