Astronomers have discovered a Jupiter-sized planet orbiting a white dwarf in the Milky Way, marking the first time a world of its size has been seen around a dead star.
When a sun-like star approaches the end of its life, it enters its giant phase, before pushing its outer layers, leaving a small white core, known as a white dwarf.
Observations from the Keck Observatory in Hawaii allowed the team from Australia and New Zealand to study the system in more detail.
The team found that the gas giant, dubbed MOA2010BLG477Lb, was able to survive the death of its host star, and is now orbiting much closer than it did before.
The team said that this system, which is about 6,500 light-years away in the direction of the galactic center, is likely a good example of what might happen to Jupiter when the sun reaches the final stages of its life in about five billion years.
The planet is about 1.4 times the size of Jupiter, and is currently about two and a half times farther from its star than the distance between the Earth and the Sun.
Previous studies have explored smaller objects orbiting a white dwarf. It found that remnants of destroyed planets and debris disk planets could survive the fickle evolution of their host stars from red giants to white dwarfs.
However, simulations created by astronomers also predicted that full-sized planets could survive.
The simulations suggested that planets in an orbit similar to Jupiter, around a star no larger than eight times the size of the Sun, were most likely to remain intact.
However, until now, with the discovery of MOA2010BLG477Lb, no such world has been found by astronomers.
The gas giant planet was discovered about 2.8 astronomical units, or about 260 million miles, away from the white dwarf star, which is about half the mass of the Sun, and is a very dense star, often cramming the mass of the Sun into an Earth-size object.
This makes them significantly more difficult to find.
In the study, Joshua Blackman and colleagues obtained deep-field exposures surrounding MOA2010BLG477L, which was previously discovered through a microlensing – the only known method capable of detecting planets at such great distances from Earth.
The team found that the planet formed at the same time as the host star, rather than from debris left behind by the star when the star shed its outer layers.
This means that it somehow managed to survive after the star stopped burning hydrogen in its core, providing evidence that planets can survive in the gas giant phase.
The work supports the theory that more than half of white dwarfs are expected to have similar planetary companions.
The astronomers also said that it “probably represents a counterpart to the final stages of the Sun and Jupiter in our solar system.”
The results were published in the journal Nature.
Source: Daily Mail