Scientists have discovered two new exoplanet candidates orbiting a star some 300 light-years from Earth, and early indications suggest that this distant solar system harbours a dark, turbulent history.
The star in question, called HIP 68468, is what’s called a solar twin, meaning it’s similar to our own Sun in terms of temperature, age, and composition. But HIP 68468 looks to have consumed and destroyed one of the worlds that once orbited it, thanks to some tell-tale signs left behind at this (alleged) cosmic crime scene.
An international team of astronomers led by Jorge Melendez at the University of São Paulo in Brazil studied HIP 68468 using the 3.6-metre telescope at the La Silla Observatory in Chile, and detected two new planet candidates in orbit around it.
foto credit NASA
One of these – called HIP 68468c – is a super-Neptune, meaning an astronomical object that is more massive then the planet Neptune. In this case, HIP 68468c has a mass about 50 percent larger than that of Neptune. The other new planet candidate – HIP 68468b – is a super-Earth, which is a planet with a mass higher than Earth’s, but lesser than Uranus and Neptune. What’s notable about HIP 68468b, which has three times the mass of Earth, is that it’s the first super-Earth scientists have found orbiting a solar twin.
When the team analysed the star’s composition, they found four times more lithium than they expected for a star of its age – 6 billion years – along with evidence of a surplus of refractory elements: heat-resistant metals that are abundant in rocky planets.
“It can be very hard to know the history of a particular star, but once in a while we get lucky and find stars with chemical compositions that likely came from in-falling planets,” says astronomer Debra Fischer from Yale University, who was not involved in the research.
Scientists think our own Solar System could go the same way in enough time too, with projections that the Sun will swallow Mercury, Venus, and potentially even Earth in about a billion years or so.
And if this does happen, it might not even be the first time our Sun has consumed a world.