Astronomers have just spotted a cosmic cannonball.
A star about 730 light-years away orbits an exoplanet the size of an exoplanet, but its density is incredible. Astronomers have determined that the world, called TOI-4603b, has nearly 13 Jupiter masses.
This means that it is almost 3 times denser than Earth and a little more than 9 times denser than Jupiter. And it's really lovely with its star, orbiting very close, only 7.25 days.
"It is one of the most massive and densest transit giants known to date," the Indian Physical Research Laboratory leads, "and is a valuable addition to fewer than five massive close planets." Among the giant planets in the overlapping regions of massive planets and low-mass brown dwarfs, further understanding of the processes that lead to their formation is needed. ”
Theoretically, planets have a limit to their masses. That's because, beyond a certain critical limit, the temperature and pressure of the core are enough to ignite, the process by which atoms come together to produce heavier elements.
For a star, the minimum mass at which this process begins is about 85 Jupiters; At that time, hydrogen atoms begin to fuse into helium.
The upper mass limit of the planet is thought to be about 13 Jupiters. Objects that cross the gap between them are called brown dwarfs. These do not have enough mass for hydrogen fusion; However, their core can be fused with deuterium, an isotope of heavy hydrogen that doesn't require as much heat and pressure.
Stars form from top to bottom when dense clumps in molecular clouds collapse under gravity to form protostars. The star then grows by sucking material from the surrounding clouds, which is arranged into a disk.
The dust and gas left behind after this process form planets, and as the rubble pieces begin to stick together, the planets start from the bottom up, eventually forming clumps that grow into planets.
Brown dwarfs are thought to be like stars, formed by a cloud of molecules that collapse under gravity. They are usually found orbiting stars at considerable distances, at least five astronomical units (AU) — which is five times the distance between Earth and the Sun.
Astronomers believe they form in a similar way to stars, both collapsing from a cloud of material, and have a striking brown dwarf "desert" orbiting very closely.
TOI-4603b was originally discovered in data from NASA's Exoplanet Search Space Telescope, which studies patches of the sky for faint, regular starlight descent that indicates the presence of orbiting exoplanets. TESS data suggest that a world with a radius of 1.042 times Jupiter orbits its star in just over a week.
Radial velocity measurements are then sought. This is the amount by which exoplanet's gravity moves its host star because the two bodies orbit a common center of gravity. If you know the mass of a star, you can calculate the mass of an exoplanet by calculating how much the star moves around it.
This is how the researchers arrived at TOI-4603b's mass 12.89 times that of Jupiter. Combining this with the radius of the object, the team came up with an average density of 14.1 grams per cubic centimeter. For context, the density of the Earth is 5.51 grams per cubic centimeter. Jupiter is 1.33 grams per cubic centimeter. The density of lead is 11.3 grams per cubic centimeter.
For example, a brown dwarf with a radius of about 0.87 times that of Jupiter and a mass of about these things can become denser than TOI-4603b.
TOI-4603b meets most criteria for being classified as an exoplanet. But it's on the cusp of the mass limit of brown dwarfs, meaning it could be an important world for understanding how brown dwarfs and giant planets form and how their relationship to stars evolves.
For example, exoplanets have distinctly elliptical or eccentric orbits, indicating that they are still in it. The star also has a brown dwarf companion with an orbital distance of about 1.8 astronomical units that may have gravitational interactions with TOI-4603b. These clues suggest that exoplanets are migrating towards their stars from more distant locations.
A similar object is a world called HATS-70b, which has 12.9 times the mass and 1.384 times the radius of Jupiter, is less dense than TOI-4603b, but is equally close to its star and is also showing signs of migration.