JWST telescope finds traces of planetary collisions in young stars

The formation of planetary systems is accompanied by collisions of large bodies, but it is almost impossible to directly observe such events at long distances. Astronomers have found a way to study their effects on the composition of dust around young stars. About how scientists use dust to determine the nature of collisions in emerging planetary systems, see the Izvestia article.

Dust instead of collision: What the JWST telescope saw

The work was published in the scientific journal The Astrophysical Journal. Astronomers led by Kate Su from the Institute of Space Sciences in Boulder studied 21 extreme debris disks around young stars. Five objects were included in the sample based on archival observations of the Spitzer Space Telescope, and 16 more were studied using the James Webb Space Telescope (JWST). Of the last 12 systems, they were observed for the first time.

The extreme debris disks are characterized by large amounts of warm dust, very fine dust particles, and irregular changes in brightness in the infrared range. It is believed that such characteristics can occur after large collisions of bodies in the forming planetary systems. The scientists did not directly observe the collisions themselves — they drew conclusions based on the properties of the substance left after them.

Astronomers have reported on the possible birth of a planet from the matter of a dead star.

Two types of dust: what she said about the collisions

According to the dust composition, the researchers divided the studied systems into two main groups — with high and low silica content. An example of a silica-rich material on Earth is volcanic glass such as obsidian. In particular, the crystalline silicate forsterite was found in systems with a lower silica content.

About a third of the disks were found to be rich in silica. According to the researchers, such systems could have formed after extremely energetic collisions of bodies of approximately Martian size. With such impacts, a significant part of the stone substance could melt or evaporate.

In other systems, the silica content was lower. They are associated with less energetic collisions, including tangential impacts of bodies about the size of the moon. At the same time, we are talking about interpreting the composition of dust, and not about directly measuring the size of colliding objects.

The age of the stars helped to restore the history of the systems

There was also a difference in the age of the stars between the two groups. Silica-containing extreme disks have so far been detected only in stars younger than 300 million years old. Disks with a low silica content were found in stars of a wider range of ages.

According to scientists, this may correspond to different stages of the formation of planetary systems. In the early stages, when rocky planets are still actively forming, especially powerful collisions of large bodies are possible. Weaker collisions and related changes in the amount of dust may occur later.

The observed brightness of such disks can also change over time. Researchers attribute this to changes in the orbits of the debris formed after collisions and new impacts between them.

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The history of the Moon: what kind of trace could a similar impact leave

The age distribution of silica-containing disks turned out to be comparable with the ideas about the early history of stone planets. Computer models show that terrestrial planets should form during the first few hundred million years of the system's existence.

This period also corresponds to estimates that the Earth and Moon formed about 100 million years after the appearance of the Sun. According to one of the main hypotheses, the Moon appeared after the collision of the young Earth with a body about the size of Mars.

Observations of extreme disks do not directly confirm this particular history of the Moon. They show that collisions of this magnitude correspond to one of the types of processes that can occur in young planetary systems.

A rare stage helps to understand the birth of planets

Extreme debris disks are relatively rare: according to available observations, signs of such a stage are found in about 1% of young stars. At the same time, it is precisely such systems that make it possible to study the consequences of large collisions that cannot be observed directly.

The authors believe that analyzing the mineralogical composition of dust helps to distinguish the conditions under which collisions occurred and track changes in planetary systems over time. Such observations can provide more information about how rocky planets form and how systems change after their appearance.

However, many questions remain open. In particular, scientists will have to observe more such systems to verify whether silica-rich disks are found only in young stars and how accurately their composition reflects the nature of collisions.