Giant planet probably generated by planetary collisions discovered

An international team of astronomers has discovered a new planet that is denser than steel. The planet in question has been dubbed TOI-1853b, and its mass is almost twice that of any other known planet of its size, while its density is incredibly high. This should mean that it is made up of a higher proportion of rock than would normally be expected at this scale.

The study, published in Nature and led by Luca Naponiello of the University of Rome Tor Vergata and the University of Bristol, suggests that TOI-1853b is indeed the result of planetary collisions. These massive impacts would have removed some of the lighter atmosphere and water, leaving behind a variety of rocks.

Carter: "Strong evidence for high-energy collisions".

Phil Carter, a research associate at Bristol's School of Physics and co-author of the paper, said: "We have clear evidence of high-energy collisions between planetary bodies in our solar system, such as the existence of the Earth's Moon, and good evidence from a small number of exoplanets. And further, "We know that there is a huge diversity of planets in exoplanet systems; many have no analogues in our Solar System, but often have masses and compositions between those of the rocky planets and Neptune/Uranus (the ice giants).

Carter added, "Our contribution to the study was to model extreme giant impacts that could potentially remove the lighter atmosphere and water/ice from the original larger planet to produce the measured extreme density. We found that the initial planetary body would likely have to be water-rich and undergo an extreme giant impact at greater than 75 km/s to produce TOI-1853b as observed.

A density greater than steel

This planet provides new evidence for the prevalence of giant impacts in planet formation throughout the galaxy. This discovery helps link solar system-based theories of planet formation to exoplanet formation. The discovery of this extreme planet provides new information about the formation and evolution of planetary systems.

Graduate student and co-author Jingyao Dou said, "This planet is amazing! TOI-1853b is the size of Neptune but has a density greater than that of steel. Our work shows that this could only happen if the planet experienced extremely energetic planet-planet collisions during its formation".

Dou continued, "These collisions stripped away some of the lighter atmosphere and water, leaving behind a significantly rock-enriched, high-density planet."

The team now plans detailed follow-up observations of TOI-1853b to try to detect any residual atmosphere and study its composition. Associate Professor and co-author Dr. Zoë Leinhardt concluded, "We had never studied such extreme giant impacts before, because they were not something we expected. There is still a lot of work to be done to improve the material models underlying our simulations and to extend the range of extreme giant impacts modeled".

Another Neptune-like planet

Another example of a Neptune-like planet is GJ 436 b, an exoplanet in the constellation Leo with a mass similar to that of Neptune. However, research in this field is constantly evolving, and new exoplanets are being discovered and studied on a regular basis. Here is some key information about GJ 436 b:

• Orbital characteristics: GJ 436 b orbits very close to its parent star, with an orbital period of about 2.64 days. Its distance from the star is very small compared to the distance between the Earth and the Sun, which means that it is a hot planet, subject to high temperatures.
• Size and mass: GJ 436 b has an estimated mass of about 22 times that of Earth and is therefore considered a "Hot Neptune" or "Jovian Hot Neptune" type planet. Its exact size and composition have not been determined, but it is likely to have a rocky core surrounded by a gaseous atmosphere.
• Atmosphere and Composition: The atmospheric composition of GJ 436 b is still being studied. However, it is believed to contain a variety of light gases such as hydrogen and helium, as well as compounds such as water, methane, and ammonia.
• Tidal effect: Due to its extreme proximity to its parent star, GJ 436 b may experience a significant tidal effect. This could lead to an asymmetry in its temperature distribution, with one side receiving more stellar radiation.
• Atmosphere study: GJ 436 b has been the subject of studies to better understand the atmospheres of hot Neptune-type planets. Scientists have tried to detect the presence of molecules in the planet's atmosphere through spectroscopic observations as the planet passes in front of its parent star.