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Unique family of alien worlds found locked in an orderly resonance dance
Scott Sutherland
mercredi, 27 janvier 2021 à 06:11 - The orderly dance of this disorderly collection of worlds challenges assumptions about how planet systems form
Astronomers have discovered a planetary system that has only gotten stranger the more they have looked at it.
In the southern constellation of Sculptor, a nondescript orange star was flagged by NASA s Transiting Exoplanet Survey Satellite (TESS) after the telescope spotted the tell-tale signs that planets were orbiting around it. TOI-178, as it came to be called, is a bit smaller and dimmer than our Sun. Observations by TESS recorded evidence for transits when the star s light dims slightly as a planet passes in front of it of at least one planet, or perhaps two.
Six Alien Planets Have Been Found Locked in a Rare, Complex Orbital Dance
8 FEBRUARY 2021
A planetary system 200 light-years away has been found locked in a rare orbital dance. Of the six exoplanets orbiting a star named TOI-178, the five outermost follow rhythmic orbital periods, with each linked to the planets on either side.
Such a dance is called a chain of resonance, and it s only rarely seen. But it can reveal something about how planetary systems form.
Orbital resonances aren t uncommon. Basically, they mean that the orbital periods of two bodies can be described as a ratio.
A few examples can be found in the Solar System. There s Pluto and Neptune - for every two orbits of Pluto around the Sun, Neptune goes around thrice; that s a 2:3 resonance. And three moons of Jupiter are in a resonance chain. For every one orbit of Ganymede, Europa goes around twice and Io four times; that s a 1:2:4 resonance.