Astronomers in Leiden have succeeded in calculating the first 100 million years of the history of the Oort Cloud. And this leads to some interesting discoveries.
New comets regularly roam the inner solar system, disappearing from view for thousands, if not tens of thousands of years. These space rocks would come from the still hypothetical Oort cloud: a huge collection of comets located at the edge of our solar system. However, much was still unknown about this alleged cloud. But it brings a new investigation switch.
The existence of the Oort cloud was suggested in 1950 by the Dutch astronomer Jan Hendrik Oort. This cloud would explain the ever new comets with elongated orbits in our solar system. The disturbances of comets in this cloud – for example, stars passing through our solar system – would drag the wedge of some of them out of the Oort cloud, landing in an elliptical orbit around the sun, passing inside our solar system.
How the Oort Cloud came about has been a mystery so far. The story goes that the Oort cloud was born in the early days of our solar system. But exactly how it happened is shrouded in mystery. It is because a series of events takes place that a computer can hardly reproduce in its entirety. Some processes lasted only a few years and occurred at relatively short distances, comparable to the distance between the Earth and the Sun. Other processes took billions of years and took place light years away, comparable to the distances between stars. “If you want to calculate everything in a computer, you will inevitably be stuck,” says Simon Portegies Zwart, an astronomer at Leiden University. “That is why, so far, only single events have been simulated.”
But a team of astronomers from Leiden have now succeeded in mapping the entire origin of the Oort cloud. In their study, they calculated the first 100 million years of the cloud’s supposed history. How did they handle it? As with previous studies, they started off with individual events. They then succeeded in connecting these separate events. They used the end result of the first calculation as a starting point for the next. In this way, a complete picture of the formation and early years of the Oort Cloud emerged.
The results confirm what people already thought: The Oort Cloud is a remnant of the protoplanetary disk of gas and dust that formed our solar system about 4.6 billion years ago. Oort cloud comets originate from roughly two different places in the universe. The first part of the objects comes from our own solar system. They are debris and asteroids thrown by large planets. Sometimes it went wrong. And this debris can still be found in the asteroid belt between Mars and Jupiter. The second part of the objects come from other stars, say the researchers. When the sun had just emerged, there were a thousand other stars nearby. The Oort cloud may have captured comets that originally belonged to these other stars.
Not only were the researchers able to confirm theories, but they were also able to disprove a number of events. For example, the new results show that the Oort cloud formed relatively late, when the sun had already ejected from the cluster of stars in which it was born. Further, the Leiden astronomers argue that an assumption made in 2005 that the Oort Cloud was the result of a migration of giant planets into the solar system – and also explained the many ancient craters on the moon – is incorrect. .
The findings give us a whole new look at the mysterious Oort Cloud. “With our calculations, we show that the Oort cloud arose from a sort of cosmic conspiracy,” concludes Portegies Zwart. “Nearby stars, planets, and the Milky Way all play a role in this. Each of the separate processes alone could not explain the Oort cloud. You really need the interaction and the right choreography of each process. And this seems to be explained quite logically by the origin of the stars. So, although the Oort cloud is complicated to form, it is probably not unique. “
How likely is it that all of this actually happened? “Despair played tricks on us regularly,” says Portegies Zwart. “It wasn’t until the math was done that all of the pieces of the puzzle suddenly fell into place and it all felt very natural and obvious. I think it’s one of the best things about being a scientist. You suddenly see how much we thought about this problem for decades until it became very natural. “