The Solar System was born in chaos. The building blocks of life were delivered by the collision that shaped and built the Earth. Without things hitting each other, we might not be here.
Our Solar System is a relatively calm place because most of the collisions are in the past. Astronomers can see the aftermath of frequent collisions in other younger solar systems.
There is an opportunity to learn about planet formation after a collision. Astronomers use telescopes to figure out what happened when objects collide. The aftermath of a collision around a young star named HD 166191 was tracked by Astronomers using the Spitzer Space Telescope and other facilities.
“By looking at dusty debris disks around young stars, we can essentially look back in time and see the processes that may have shaped our own solar system.”
Kate Su, study lead author, University of Arizona.
HD 166191 is a ten million-year-old star. It caught the attention of the astronomer because it was a disk transitioning to a debris disk. Years of observations showed a debris cloud in front of the star after a collision.
Kate Su is an astronomer at the University of Arizona. The paper can be found online at The Astrophysical Journal.
The processes that may have shaped our solar system can be seen by looking at dusty debris disks around young stars.
HD 166191 was being watched by the team of astronomer. The young solar system was observed more than 100 times. The system is too young to have fully-grown planets, but planetesimals and even dwarf planets are bound to be around the star. They are too small to see in telescopes.
The building blocks of planets are planetesimals. Blocks don't accrete in an orderly fashion. Instead, they crash into each other, sometimes breaking into smaller chunks, and eventually forming larger rocky planets.
Dust clouds are visible in the sky. The star's energy strikes the dust and emits light. The team saw that in their observations. The team observed an increase in brightness at HD 166191. The increase suggests that the amount of dust around the star has gone up.
The debris cloud from the collision was seen by the researchers over the years. When the collision occurred, they calculated the size of the objects and the speed of the impact. They watched the dispersal of the debris cloud.
The debris cloud was long. The cloud was three times larger than the star. The increase in the light's wavelength suggested something else. The debris cloud had to be much larger in order for it to pass directly in front of the star. It had to cover an area hundreds of times larger than the star. That is the only explanation for the light.
The objects in the collisions had to be large enough to produce that amount of dust. NASA's Dawn mission visited a dwarf planet in the Solar System in 2011. The objects that collided around HD 166191 were about the same size as Vesta, about 330 miles in diameter, according to the astronomer behind the study.
Some of the material was damaged in the collision. The impact generated a chain-reaction of smaller crashes between debris and other objects. The cascade of multiple collisions in mid-year explains the large amount of dust and the increase in energy.
The dust cloud expanded and became more transparent. The debris from the collision was dispersed around the solar system. The amount of dust in the system had doubled by the time the year was over, but the dust cloud that transited in front of the star was no longer visible.
These observations can be used by scientists to study planets and solar systems. The formation of a planet is largely hidden. Only certain observatories can pierce the veil of dust in young solar systems. The lanes carved in the dust around young solar systems can be seen thanks to ALMA.
The study lead author said that they may get a better idea of how frequently rocky planets form around other stars.
HD 166191 will be watched to see how it develops. Astronomers think that it is transitioning from aplanetary disk to a debris disk. The star isn't adding any more material. The system is still dusty, but the star has dissipated most of the gas left over from star formation via photoevaporation.
Theoretical simulations show that the very existence of planets depends on the merging of planetary embryos. During the first 200 million years after the star formation, large-scale collision among planetesimals and planetary embryos are expected.
There were many Moon-sized to Mars-sized rocky bodies in the inner Solar System. The Moon is thought to have formed when a planet called Theia collided with the Earth. The architecture of the inner Solar System is the result of many more crashes.
Astronomers are stuck in the Solar System. They have to study distant systems like HD 166191 to see what happens.
The evolutionary state of the system makes it important to learn about the process of planetary formation through future observations.
What is next for HD 166191? The authors wrote that we might be witnessing the early giant impact phase in assembling terrestrial planets in the inner zone.
The importance of continuous monitoring is demonstrated by the nature of extremely dusty systems. They conclude that future observations of this unique system would shed light on our understanding of planetary architecture.
Bring on the further observations.
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