Discoveries

September 05, 2023

Violent Past, Hardcore Future

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A newly discovered exoplanet called TOI-1853b has left astronomers scratching their heads, Science Alert reported.

Scientists wrote in a new paper that the outer world is a bit smaller than Neptune but has an astonishingly high density, almost twice that of Earth. This suggests it’s packed with rocks, which is quite unusual for a planet its size.

Researchers proposed that TOI-1853b might have had a very wild and violent past: The exoplanet began as the core of a large gas giant that lost its gassy atmosphere in a dramatic collision with another planet.

When they ran computer simulations, the scientists found that for it to end up with a density “higher than steel,” it needed “to be water-rich and suffer an extreme giant impact at a speed of greater than 75 kilometers per second in order to produce TOI-1853b as it is observed,” according to co-author Phil Carter.

Carter and his team also noted that TOI-1853b lives in a region of space known as the “Neptunian desert,” where Neptune-sized planets closely orbit their host star.

So far, astronomers have found more than 5,500 exoplanets, but only a handful of them fit the description of TOI-1853b. Understanding why this region is so empty could help us learn more about how planets form and evolve.

Next, the team plans to study TOI-1853b more closely to see if it still has any traces of an atmosphere and to analyze its makeup, which could also confirm whether the collision theory is correct.

This story originally appeared in the September 05, 2023 newsletter, Stumbling To the Starting Line.