At the time, when every star will become older then it will shrink the fraction of its radius. Then this older star will become a White Dwarf star that unable to sustain energy from nuclear fusion.

All the white dwarf stars have faint luminosity which comes from the emission of stored thermal energy. While studying the older exoplanetary systems around the white dwarf, astronomer gets some hints about fate about the solar planetary system.

In this regard, they have studied the atmosphere of a White Dwarf star. From which, they found that if any materials are trying to accumulate within the White dwarf's atmosphere. Then the materials are splits into the constituent chemical compounds. After that, it will be separated into different chemical layers according to their atomic weight.

According to result, scientists are confirmed about the chemical compound contains at the uppermost layer of the White dwarf. They analyzed that the layer comprises only a combination of hydrogen, helium, and carbon.

However, a comprehensive study about 1000 White dwarf showed the presence of other material in the atmosphere. It displayed that the material looks like some form of rocks. In fact, these materials are accumulated and caused pollution around the Dwarf star atmosphere.

Furthermore, Scientists are trying to figure out about the origin of these rocky materials around White dwarf. Though they unsure about the origin. To solve this, Astronomer Matt Payne and Matt Holman from Harvard-Smithsonian Center for Astrophysics developed a series of computer-based simulations. In this regard, they published their article in the monthly notice of Royal Astronomical Society.

Actually, the simulation is based on the late evolution of planetary systems. They hoped that the simulation may help them to understand the origin of the materials around the White dwarf. According to news portal of Smithsonian Astrophysical observatory, during the strong planetary interaction, the exomoons are easily diverted from its orbit. 

But the biggest question is where these free moons are going? However, Astronomers presume that they may be accrete themselves and create pollution around the White dwarf. Some other theory presumes the polluting materials as the fragment of small asteroids.

When an asteroid collides with those free moons then it scattered towards the White dwarf. Practically there is some computational limitation about the simulation. As the representation of complex cosmic phenomenon is too much difficult means, it isn't easy to get an accurate result.