The hunt for moons in the orbit of distant planets can find massive exoloons.
In 2012, a team of scientists from the Kepler mission announced that they would begin hunting for moons revolving around distant exoplanets. And while the telescope finds thousands of exoplanets, the moons remain out of sight.
The main problem is that for the “visibility” of the Moon, its mass should be about 10% of the mass of the Earth, or an approximate mass of Mars. This is 10 times the largest moon in the Solar System.
And while the formation of planetary satellites seemed to be a natural by-product of the formation of planets, scientist Amy Barr of the Planetological Institute wondered whether large moons (perhaps even the size of Earth) could form. And if so, how would they be located in the galaxy?
Using simulations and simulations, Barr and her colleagues discovered that in theory there is a chance that the super-plasma of the moon will form around a rocky and gas planet. But only if the planets themselves are huge enough. Large rocky satellites can be created as a result of a collision between the giant rocky worlds. Then the exolunas around the gas giants could be produced due to joint accretion or capture.
“We have the first results of the masses of the moons, which can be formed with a different set of effects within the possible limits of exoplanetary systems,” said Barr. “The main thing is that we have shown that it is possible to form exoles with masses above theoretical maxima. Kepler continues to examine satellites of more than 1/10 of the Earth’s mass. ” To detect planets passing in front of the parent star's disk, Kepler uses the transit method (temporary brightness decrease). The same technique should help find exoles. Therefore, a team from the Harvard-Smithsonian Center for Astrophysics opened the hunt. But it all seemed like an empty idea, because of the size that was needed to be noticed.
However, the solar systems found by Kepler strongly differ from ours. And the most common size of the planets in the Kepler data is a new class, the “super-Earth”. Their scale varies between Earth and Neptune.
“So far, little is known about how the satellite formation processes that we use can scale to different planetary masses and stellar conditions,” writes Barr in an article.
Simulation of the impact of a rocky-iron planet the size of Venus on a planet with 6th masses of the Earth. The collision creates a massive enough disk of debris, liquid and steam to create a moon with 0.1 Earth mass.
Using hydrodynamic modeling, Barr can determine how much material will be in orbit after a collision between two rocky super-Earths. A strike between planets from two to seven Earth masses will release enough material to create a large satellite that can detect transit Kepler.
“These results almost coincide with the blow that forms the moon, but the disk will be much hotter and more massive,” says Barr. Her models suggest that detectable rocky exoles can be produced under various shock conditions, as well as connected by large host planets. In addition, they can be formed as a result of joint accretion around growing gas giants, or by capturing wandering bodies, or else other processes that are not observed in our system. Barr also looked at modern theories about the formation of the moon in the solar system, and tried to apply them to exoles.
“Some of the theories, such as divisions, may work in other systems,” she said. “Soon we will get new observatories and will be able to double-check some old ideas.”
At this point, Kepler and the K2 mission found 2476 confirmed planets, with an additional 5216 “candidate planets”. The exolun count is still zero, but Barr continues his search.
