There appears to be a star similar to our own Sun some 300 light years away from us that has a nasty habit of devouring the planets in its own system.
Image Credit: Gabi Perez / Instituto de Astrofísica de Canarias
Reporting in a paper for Astronomy & Astrophysics, researchers have determined that the star, named HIP 68468, is fairly similar to our own Sun, although it’s 6 billion years old compared to our Sun’s age of 4.5 billion years.
That aside, because the two systems are so similar, astronomers led by Jorge Melendez from the University of São Paulo in Brazil had their eyes on it for some time with the 3.6-metre telescope at the La Silla Observatory in Chile, and they’ve found two exoplanets orbiting HIP 68468.
One of the two exoplanets is said to be a “super Neptune,” which is a planet that’s like Neptune, but larger. HIP 68468c, as it’s being called, is around 50% larger than the Neptune we’re used to in our own Solar System and has about 26 times the mass of Earth.
The other of the exoplanets is dubbed HIP 68468b and is a “super Earth,” which just like a super Neptune, only with the Earthly spin on it, is a planet that’s like Earth, but larger. This super Earth is said to have about three times the mass of our planet, and interestingly, it’s the first time we’ve ever found a super Earth in a system with a star similar to our own Sun.
While observing the chemical makeup of the star HIP 68468, they found something peculiar; the atmosphere had traces of as much as four times the lithium you would expect to find in a star of its age, as well as refractory metals that are often found in Earth-like rocky planets.
Because we understand this system to be a lot like our own due to the Star’s age and such, it was pretty strange to see this abundance of materials in the star’s atmosphere, because it’s not present in our own.
The idea is that this star might have swallowed a planet that was once a part of the system, suggesting there were once three planets instead of two. Sometimes planets can stray too close to their host stars, and gravity takes care of the rest.
Once there, the planet is essentially vaporized by the extreme heat, and all of its elements become one with the star, which is what we’re seeing in this case.
"This study of HIP68468 is a post-mortem of this process happening around another star similar to our sun. The discovery deepens our understanding of the evolution of planetary systems," senior author Professor Debra Fischer from Yale University said in a statement.
Interestingly, as both of the remaining planets are also in close orbits around their host star, they each may also see the same fate at some point in the distant future, being swallowed up by their host star and merging their elemental mass with it.
Planet-devouring stars probably aren’t as rare as we think. As many as 15% of the Sun-like stars we’re observing currently have excess lithium in them, which suggests these systems may face similar conditions.
Because the system is a lot like our own Solar System, it brings our attention to the Sun. It will be a long time in the future before the Sun ever swells enough to swallow the Earth and our surrounding planetary neighbors.
Fortunately, we have a long time to study the rest of the universe before that happens.