Astronomers discover an exoplanet denser than steel
crew CV‘s astronomy (Now streaming on Peacock) He will be the first human to set eyes on another star system. At least, they would be if they survived the journey. Historically, science fiction has been dominated by distant worlds and strange peoples that closely resemble the world and people we already know. However, the more we learn, the more we realize that the universe is full of all kinds of worlds imaginable, some of which are very strange.
A world roughly twice as dense as Earth
Enter, the exoplanet TOI-1853b, a Neptune-sized world not too far from here. It orbits a K2 dwarf star – a main sequence star that lies between a conventional red dwarf and familiar yellow stars like our Sun – with a mass of about 85% that of the Sun, and located about 545 light-years from here. Notes published in the journal nature Indicates that it is denser than stainless steel.
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The planet orbits in a tight 1.24-day orbit, one of the heaviest worlds we’ve ever seen. Astronomers classify it as Neptune-like because of its approximate size. TOI-1853b has a radius of about 3.5 times that of Earth and carries about 73 Earth masses in its planetary pockets. For comparison, Neptune’s diameter is about four times Earth’s diameter, about the same as TOI-1853b, but only about 17 Earth masses.
By analyzing these two numbers (diameter and mass), scientists can calculate the average density of the world, which can tell us what material the planet might be made of. Earth, for example, has an average density of 5.5 grams per cubic centimeter. Gas planets are usually less dense. You’ve probably heard that Saturn can float in water (provided you have a large enough cup and can solve a number of other physics problems) and that’s true. In fact, Neptune is the densest planet in the solar system on the other side of the asteroid belt, with a density of 1.6 grams per cubic centimeter.
TOI-1853b puts our giant planets to shame with an average density of 9.7 grams per cubic centimeter. This is dense enough to overwhelm steel, with an average density of just 8.05 grams per cubic centimeter. This is a difficult planet.
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To explain its strange circumstances, astronomers suspect that the planet was originally water-rich and moved along a highly eccentric orbit. As it orbited its parent star, the closest and furthest from the center of the system, it collided with one or more other planets. Researchers estimate that one or more impacts occurred, each at speeds exceeding 75 kilometers per second (270,000 kilometers per hour/167,000 mph). These collisions would have stripped light elements such as water and gases from the atmosphere, leaving behind only dense, rocky material.
It likely started out as a planet more like our gas and ice giants, but migrated closer to its star, smashing up other worlds along the way. By the time he reached his current location, he had gathered the power of six planets his size. It’s dangerous out there, you never know when an entire world might absorb your world to make itself stronger.
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