In what ways can two planets have different densities? New research can condemn the cause of violent clashes.
In our solar system, every inner planet is a small rock world with similar densities, and the outer planets are gas giants with similar densities of their own. But not all solar systems are like us.
The Kepler Mission has discovered a variety of extraterrestrial planets for nine years. Thanks to its mission, we now have only 2,000 alien planets with less than three Earth radii. And although these 2,000 planets have a fairly narrow range of sizes, their density can vary greatly.
This new article is published by Nature Astronomy by astronomer Aldo S. Bonomo and Mario Tamasso (Astrophysicist Center) of Istituto Nazionale Di Astrofisica. Harvard & Smithsonian (CfA) astrophysicist Li Zeng. As many colleagues as I could not get on the list were involved.
Some of the previously mentioned alien planets, 2,000, are less dense than Neptune gas composed of low-density volatiles, but some have a density higher than Earth, which is composed of rock (about 32% iron). Using the Kepler-107 system, we want to understand how planets of similar size to the same system can have varying densities.
The team focused on the Kepler-107 system. It contains four sub-Neptune sized planets (Kepler-107b, c, d and e). The two innermost planets, 107b and 107c, have roughly the same radius of the Earth's radii of 1.5 and 1.6, but 107c is twice as dense as 107b. How can these twins be part of a very dense planetary system and have different configurations?
This is one of the many interesting extraterrestrial planetary systems discovered and characterized by the Kepler Space Telescope. "
Li Zeng, Department of Earth and Planetary Sciences, Harvard University.
The short answer is that they have been formed under very different conditions or dramatically changed to dramatically change their density.
Before Kepler appeared, only astronomers had our solar system. And in our system, Jupiter, Saturn, Uranus, and Neptune appear to form outside the primitive planetary discs from the cold ices and gases that make up the material of the primordial solar system. In the inner zone of the young solar system, rocky planets are made of materials that survive the radiation of the sun like silicates and iron.
But the Kepler mission showed us that it is only one path that the solar system can take, which we consider to be the norm, our own solar system. Kepler has discovered a number of "hot jupiters", or so-called "Hot Jupiters," in a large gas world orbiting a very close orbit to their star, They could not have formed too close to the stars because they did not survive.
There is evidence that Jupiter was formed in the outer zone of our solar system and then moved closer to the Sun before we could find our way to the present orbit. However, as far as we know, the inner rock planets have not moved. They were formed here in the inner solar system.
The Kepler 107 system also shows that the solar system can be formed differently from our own solar system, and the density can change due to a fatal collision between the two worlds.
The radii of the Keplers 107b and 107c are 1.53 and 1.59, the orbital periods are 3.18 and 4.9 days, respectively, and the densities are 5.3 and 12.65 g / cm & lt; 3 & gt ;, respectively. What can explain the huge density imbalance? If solar radiation is responsible, did not you boil the volatiles and submit them to both planets? Also, outer planets have greater density, not inner density.
The astronomer team claims to be a fatal collision that is responsible for heterogeneous density.
What they thought was that Kepler 107c (the outer and denser planet) took the silicate mantle and suffered a catastrophic collision, leaving only the iron core.
"This is one of the many exciting extraterrestrial systems that Kepler Space Telescopes have discovered and characterized," says Li Zeng of Harvard. "This discovery confirmed previous theoretical research suggesting that a massive impact between planets played a role during planetary formation. The TESS mission is expected to find more such cases. "
Planetary conflict is not a new idea. Evidence shows that the Earth's Moon was created as a result of a fatal collision between Earth and another body called Theia. This new study suggests that it can be much more general than you might think.
Astronomers expect to find many other examples, such as Kepler 107, if fatal confusion frequently occurs in the planetary system. Because a greater number of extraterrestrial planetary densities are more accurately determined.