Have a Look on the Formation of Solar System

Approximately 4,500 million years ago, gravity gathered a cloud of dust and gas to form our solar system. While scientists are not sure of the exact nature of the process, observations of young star systems combined with computer simulations have allowed them to develop three models of what might have happened many years ago.

Birth of the sun

A massive concentration of gas and interstellar dust created a molecular cloud that would form the birthplace of the sun. Cold temperatures caused the gas to clump together, becoming denser and denser. The densest parts of the cloud began to collapse under their own gravity, forming a large number of young stellar objects known as protostars. Gravity continued to collapse the material on the child object, creating a star and a disc of material from which the planets would form. When the merger began, the star began to launch a stellar wind that helped clear the debris and prevented it from falling inward.

Although gas and dust envelop young stars at visible wavelengths, infrared telescopes have plumbed many clouds from the Milky Way galaxy to reveal the home environment of other stars. Scientists have applied what they have seen in other systems to our own star.

After the sun formed, a massive disk of material surrounded it for about 100 million years. That may seem a more than enough time for the planets to form, but in astronomical terms, it is a blink of an eye. As the newborn sun warmed the disk, the gas quickly evaporated, which gave the planets and newborn moons a short period of time to collect it.

Training models

Scientists have developed three different models to explain how planets formed inside and outside the solar system. The first and most widely accepted model, central accumulation, works well with the formation of rocky terrestrial planets, but has problems with giant planets. The second, the accumulation of pebbles, could allow planets to form quickly with smaller materials. The third, the disc instability method, can explain the creation of giant planets.

The central accretion model

Approximately 4.6 billion years ago, the solar system was a cloud of dust and gas known as the solar nebula. Gravity collapsed the material on itself when it began to rotate, forming the sun in the center of the nebula.

With the sunrise, the remaining material began to cluster. The small particles were united, united by the force of gravity, into larger particles. The solar wind-swept lighter elements, such as hydrogen and helium, from the closest regions, leaving only heavy and rocky materials to create terrestrial worlds. But further, solar winds had less impact on lighter elements, which allowed them to join in gas giants. In this way, asteroids, comets, planets and moons were created.

Some exoplanet observations seem to confirm core accumulation as the dominant formation process. Stars with more "metals," a term astronomer use for elements other than hydrogen and helium, have more giant planets in their cores than their metal-poor cousins. According to NASA, the accumulation of nuclei suggests that small, rocky worlds should be more common than the more massive gaseous giants.

The discovery in 2005 of a giant planet with a massive nucleus orbiting the star HD 149026, similar to a sun, is an example of an exoplanet that helped strengthen the case of the accumulation of nuclei.

"This is a confirmation of the theory of the accumulation of nuclei for the formation of planets and evidence that planets of this type should exist in abundance," Greg Henry said in a press release. Henry, an astronomer at Tennessee State University in Nashville, detected the attenuation of the star.

By: Preeti Narula

Content: https://www.space.com/35526-solar-system-formation.html