agencies

Thursday, March 16, 2023 at 10:00 p.m

In new research published in the journal Monthly Notices of the Royal Astronomical Society, I used computer simulations to show that collisions between exoplanets and their moons may indeed be a regular occurrence.

Although astronomers have not reliably detected exomoons, they expect them to be abundant in the universe.

“We know there are a lot of moons in our solar system, so naturally we expect to see moons in exoplanet systems. That’s what theorists want,” said Jonathan Brandt, an astrophysicist at the University of Kansas, who was not involved in the new study. and are interested in investigating how exoplanets interact and how these interactions affect the possibility of life in distant star systems.

Gravity governs the interactions between the planet and its moons, manifesting itself in the form of tides and other effects such as tidal ebb and flow on our moon.

Meanwhile, the Earth rotates a little slower each year. These two effects are directly related, so that the Earth imparts some angular momentum to the Moon’s orbit from its rotation.

If this trade-off continues long enough, the Moon eventually becomes unbound to the Earth. Fortunately, this process takes a long time for the sun to explode before the moon is completely gone. But around some exoplanets, especially those closer to their stars than the Earth is to the Sun, this situation can develop much faster, as the planets and their “unstable” moons collide within the first billion years of their formation, according to Hansen’s calculations. (By comparison, Earth and the Moon are about 4.5 billion years old.)

In Hansen’s simulations, moons that drift away from their host planets often return with a thud, slamming into the planet and creating large clouds of dust. These dust clouds glow in the infrared, glowing and heated by starlight. But it lasted only about 10,000 years before disappearing, a “blink” in cosmic calculations.

Observations from NASA’s Wide Field Infrared Space Telescope show that every star undergoes such an event at some point in its life, Hansen said.

Because these dust clouds are so short-lived, astronomers have observed only a dozen of them.

Additionally, some astronomers do not believe these dust clouds are from exomoons, suggesting instead that they may be the result of a collision between two planets.

However, more observations are needed to understand the role of exomoons in exoplanet evolution and to determine whether these collisions could affect alien life.

“Moons are often considered beneficial. They are thought to help stabilize the tilt of the planet’s axis, making the seasons pleasant and conducive to life,” Hansen explained. However, a collision like the one in Hansen’s simulation would certainly outweigh this advantage by destroying any chance of survival in a fiery explosion.