New Discovery: The Universe Has Not Only "Three-Body" Systems, But Also Terrifying "Devourers"

Recently, "The Three-Body Problem" has become a hot topic again. As an astronomer, I certainly wouldn't miss such a great opportunity for science communication. In fact, I've always been curious about the stability of planetary systems.

In the early 17th century, Kepler published his three laws of planetary motion, revealing the orbital patterns of celestial bodies. But when multiple bodies exist in a system, the dynamics can become unstable, causing some objects to be randomly ejected. This is the astronomical foundation of "The Three-Body Problem" story.

One day, when I was first getting into astronomy, a thought struck me: Could similar random ejections happen in our own solar system? To be more specific, could our solar system have originally had far more than just the "eight planets," with one or more early planets having already been randomly ejected?

This question has lingered in my mind and became one of my research directions in astronomy.

Why Look for Twin Stars First?

To unravel this mystery, we conducted a large-scale spectroscopic survey, studying nearby stars in depth. We specifically focused on 91 pairs of twin stars that formed simultaneously and should have identical properties.

This is somewhat similar to how sociologists study identical twins. In terms of chemical composition, a pair of twins should have roughly the same elements in similar proportions. If any differences exist between these "siblings," those changes must have been caused by "environmental factors."

For example, Earth has a higher proportion of iron compared to the Sun, while the Sun has higher proportions of hydrogen and helium than Earth. Therefore, if we hypothetically dropped Earth into the Sun, the proportions of certain elements in the Sun would change—if the Sun had a twin sibling, there would now be chemical composition differences between them.

Stars Devouring Planets Is Not Rare

Initially, we approached this with an exploratory mindset: finding even one pair of different twins would have been a huge success. But unexpectedly, we found not just one pair, but more than ten.

Of course, differences between stars aren't necessarily due to devouring their planets. We also considered differences in element settling mechanisms in stellar atmospheres. To verify our hypothesis, we conducted detailed modeling and analysis.

The key point is that, compared to the Sun, Earth has a higher ratio of heavy elements to volatile elements. We found that among those twin pairs with differences, at least seven groups showed element differences consistent with an "Earth falling into the Sun" scenario.

Sherlock Holmes once said that when you eliminate all the most likely possibilities, whatever remains, however improbable, must be the truth. This applies to detectives, and certainly to astronomers as well.

So, our conclusion is that in every twelve pairs of stars, at least one star has devoured planetary material orbiting it. This research was recently published on the cover of Nature.

Interestingly, this phenomenon somewhat resembles what Liu Cixin described in his lesser-known novella "The Devourer" (about an alien civilization that consumes planets), or the famous painting "Saturn Devouring His Son" from Goya's late "Black Paintings."

Our research results show that, like in "The Three-Body Problem," many planetary systems have some degree of instability. Unlike the book's description, this instability exists even without a nearby companion star.

In recent years, some researchers studying planetary dynamics theory have pointed out that systems with massive "super-Earths" are inherently unstable. Gravitational perturbations from stars and massive planets may be enough to trigger instability. It's a bit like... if a family has many children, the house is probably chaotic most of the time.

The Real Probability of Stars Devouring Planets Is Even Higher

Despite some theoretical support, such a high devouring rate truly exceeded our expectations. This means instability in planetary systems may be more common than we previously thought. What we can observe may be just the tip of the iceberg.

First, ejected planets don't necessarily fall into their host star. In fact, planets can be ejected either inward or outward. If inward, they might be devoured by the star. But more likely, these planets get ejected out of the star system entirely, becoming "rogue planets" drifting through the cosmos.

Furthermore, even if a planet is devoured, due to convection in stellar atmospheres, these traces may disappear over time. This process is like pouring milk into coffee—it creates unique patterns on the surface, but these patterns change and eventually dissipate.

Through such observations, we discovered that roughly one in twelve stars are "devourers." However, milk patterns gradually spread until completely gone—we end up with a uniform latte. The patterns on stars work the same way, so we cannot observe devouring events that happened long ago.

In other words, although the probability we observed in our sample is one in twelve, the actual probability may be much higher. The remaining star systems may also have instability phenomena, or the ejected planets simply became rogue planets drifting through space, or the traces of devouring were smoothed away by time.

More Questions Than Answers

Although our discovery is interesting, like all scientific discoveries, the questions it raises are more important than the conclusions themselves.

One possible explanation is that planets are ejected very frequently, so at any point in time, some stars will show the "latte art" phenomenon; or stellar convection processes are very slow, allowing traces of planetary devouring to persist for long periods. However, given our incomplete understanding of multi-body system dynamics and stellar thermal convection processes, these questions require further research.

I hope our research will inspire more people to study planetary systems and their relationships with stars, unveiling these mysteries.

Perhaps a more important implication of our work is this—the flourishing of life on Earth depends on a delicate balance, and our cosmic home may be more fragile than we imagine. As an astronomer, I will continue exploring the mysteries of the universe, searching for more clues about our place in it. At the same time, I hope our research will spark more thinking about the stability of planetary systems, increasing our awareness and appreciation of our cosmic home. Only then can we better protect this land where life thrives, allowing Earth's civilization to continue flourishing.