BEIJING, Jan. 16 (Xinhua) — According tomedia reports, the nearest rocky planet to the sun is made up of very different substances compared to gas giant planets outside the solar system. This may be because billions of years ago, the solar system was divided in two by a “cosmic gate” that prevented the mix of matter inside and outside the solar system. According to a new study, the gate is actually a circle of dust and gas, more like a fence, which the study authors call the Great Divide.
Chile’s Atacama Large Millimeter Wave/Submillimeter Wave Array (ALMA) captured this image of the disk, which surrounds a young star about 450 light-years from Earth. Scientists have suggested that in the early solar system, similar disks may have formed around the sun, laying the foundation for the formation of different types of planets.
Now, the gate is located within Jupiter’s orbit and is essentially an empty space.
About 20 years ago, chemists realized that the composition of their basic components, microplanets or smaller space rocks, varied widely depending on how far they were from the sun. In the microplanets that make up peripheral wood-like planets, organic molecules (such as carbon-containing volatiles, or ice and gas) are higher than the microplanets that make up Earth-like planets , such as Earth and Mars, which are closer to the sun. However, this phenomenon is puzzling, because theoretical predictions suggest that, because of the so-called “gas resistance”, the gravitational pull of the gases around the young sun, microplanets from outside the solar system should spiral into the inner solar system.
Prior to the new study, scientists believed that “the gravitational wall that prevents the mixing of the inner and outer disks of the nascent solar system is Jupiter”. Specifically, because Jupiter is so big and its gravity so strong that it was swallowed up by Jupiter before it reaches the inner solar system, the researchers conducted computer simulations to test the theory, recreating the growth of the early solar system and its planets.
Simulations show that Jupiter is not growing fast enough to prevent all carbon-rich microplanets from entering the solar system. In fact, most of the microplanets from the outer reaches of the solar system have gone directly past the growing Jupiter. Jupiter is a very inefficient “gatekeeper”, which is like a porous boundary through which material from the outer solar system flows into the inner solar system, and Jupiter itself may allow many microplanets to pass through, meaning that planets inside and outside the solar system may have similar components.
So the scientists came up with a new theory: in the early days of the solar system, there might have been one or more ring structures, consisting of alternating high, low-pressure gas and dust around the sun. These rings prevent the microplanets from moving to the inner solar system. This hypothesis is based on observations from Chile’s Atacama Large Millimeter/Submillimeter Wave Array (ALMA): about two-fifths of young stars are surrounded by bull-eye-like disks.
These high-pressure disks may have captured a lot of dust and gathered them into different structures, such as Jupiter and Saturn, and others to Earth and Mars. One of these disks may have prevented the outer microplanets from moving to the inner solar system, creating a “big watershed,” Mr Mogizissis said. Even so, the ring is not completely sealed, allowing carbon-containing space rocks to enter the inner solar system, providing seeds for the emergence of life on Earth.
But while the authors’ work challenges past beliefs that Jupiter’s growth separates solids on the inside and outside of the solar system, they do not give the same detailed ring model, which needs to demonstrate how microplanets are captured and how these captured microplanets grow into planets. Until then, the ring model was not very convincing compared to other possible explanations. The results of the new study were published January 13 in the journal Nature Astronomy.