With this, we have discovered hundreds of stars with multiple planets scattered throughout the constellation. Each one is unique, but a system that surrounds the star 158259 HD, 88 light years away, is really special.
The star itself is around the same mass and slightly larger than the Sun – our exoplanet shoots have a minority. It is surrounded by six planets: Super-Earth and five mini-Neptunes.
After observing it for seven years, astronomers have discovered that all six of these planets rupture HD 158259 in an almost perfect orbital repositioning. This discovery could help us to better understand the mechanisms involved in the creation of a planetary system, and how they will end up in the arrangements we see.
Orbital repositioning is when the orbits of two bodies around their parent body are closely linked, as the two orbiting groups exert a gravitational effect on each other. In the Solar System, it is very rare in planetary bodies; Pluto and Neptune are perhaps the best example.
These two groups are in what is described as a 2: 3 orbital repositioning. For every two laps that Pluto does around the sun, Neptune does three. It ‘s like playing music bars at the same time, but with different signatures – two beats for the first, three for the second.
Orbital movements have also been identified in exoplanets. But each planet orbiting HD 158259 in almost 3: 2 ratio with the next planet out of the star, is also defined as a time ratio of 1.5. That means for every three orbits that each planet makes, the next outer one ends two.
Using measurements taken using the SOPHIE spectrograph and the TESS exoplanet hunting space telescope, an international team of researchers led by astronaut Nathan Hara of the University of Geneva in Switzerland was able to work out the orbits of each planet. mach.
They are all very tight. Starting closest to the star – the Super-Earth, which was revealed by TESS to be about twice the mass of the Earth – the orbits are 2.17, 3.4, 5.2, 7.9, 12, and 17.4 days.
These produce time ratios of 1.57, 1.51, 1.53, 1.51, and 1.44 between each pair of planets. That’s not quite perfect – but it’s close enough to classify HD 158259 as an amazing system.
And this, the researchers believe, is a sign that the planets orbiting the star did not create where they are now.
“There are known to be several complex systems with several planets in, or near, such as TRAPPIST-1 or Kepler-80,” explained astronaut Stephane Udry of the University of Geneva.
“It is believed that such systems go far from the star before they move towards it. In this situation, the fathers play a vital role.”
This is because these changes are thought to occur as a result of planetary embryos in the protoplanetary disc growing and migrating inward, away from the outer edge of the disc. This involves a series of orbital repositioning throughout the system.
Then, once the remaining gas from the disc releases, this can unbalance the orbital changes – and this could be what we see with HD 158259. And these tiny differences in orbital changes could tell us more about how this destabilization occurs.
“There is a wealth of information in the current deviation of the time ratios from 3: 2,” Hara said.
“With these values on the one hand, and tidal impact models on the other, we could disrupt the internal structure of the planets in a future study. In summary, The current state of the system gives us a created window. “
The research was published in Astronomy & Astronomy.
A draft of this article was first published in April 2020.