When space becomes art: discover the perfect cosmic dance of the solar system HD 110067
HD 11067 and its six planets, whose ballet is regulated like a clock. © SpaceEngine
The discovery of HD 110067 in 2020 by NASA's TESS telescope, then its exhaustive study at the end of 2023 by its CHEOPS counterpart allowed all the magic to be revealed. This star system actually continues to fascinate astronomers because of its extremely rare characteristics, because less than 1% of the Milky Way systems present this particularity which we will explain below.
HD 110067 is located in our galactic suburbs, about 100 light years away in the direction of the constellation known as Berenice's Hair. Its star, an orange dwarf, measures about 80% the size of the Sun — we will see that this data is important. Around this orange star revolve six exoplanets and it is from them that a disturbing strangeness comes…
When mathematics emerges as a great watchmaker
The orbits (or periods in astrophysics language) of the six exoplanets depend on each other in almost perfect synchronization. Thus, when the outermost planet completes one orbit in 20.59 days, the one before it completes 1.5 orbits (i.e. in 13.67 days), then the next one again 1.5, etc. It's called a orbital resonance. Nothing extraordinary so far since we observe one around Jupiter with three of its four main moons. But discovering six planets in resonance in the same solar system is mind-blowing!
Here is the HD 110067 system in animation:
The HD 110067 system is in resonance: each planet performs an orbit inscribed in the orbital duration of the other planets. © ESA
And here is this hypnotic orbital resonance of HD 110067 explained in video:
Research into the true age of the solar system is in full swing
According to our current knowledge of astrophysics, the principle of orbital resonance can just as easily stabilize a system as the opposite. It is therefore difficult to deduce the age of HD 110067 based on this parameter alone. Typically, the age of a star is determined by HR diagram. But if it works very well for stars more massive than ours, this diagram has its limits when they are less massive. And that is precisely the case here.
Initially, the age of HD 110067 was estimated at around 8 billion years, but more recent studies show that the star probably only burned out “only” 2.5 billion years ago. These new estimates are based on the star's rotation and magnetic activity, which is generally more reliable for low-mass stars.
For the moment, the six discovered planets orbit too close to their star to imagine that life could have developed there. But such mathematical harmony being a guarantee of stability, if a more distant planet, in a habitable zone – that is to say one capable of containing liquid water – were to be discovered there, who knows what it could harbor ?
