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Space boffins: Exoplanet survived hydrogen-death of its host star

Hope extended to gas giants across the universe... well, it is Friday

Those of us fatalistically counting down the minutes until the Earth is engulfed by the dying embers of the Sun in approximately 5 billion years might be offered a glimmer of hope by the news that planets – or at least gas giants – can survive the collapse of their host star.

Joshua Blackman, a postdoctoral researcher at Australia's University of Tasmania, and his colleagues have found evidence of a Jupiter-like planet orbiting a white dwarf star somewhere outside the Solar System off in the Milky Way.

It is the first time scientific evidence of a planet surviving a star's collapse has been presented, although theoretical models predicted it is possible, according to a study published in Nature.

The researchers used microlensing to detect the planet, a means of exploiting the effects of the planet's gravitational field on the passing light of a distant background star. The method can also detect remnants of stars such as white dwarfs.

Near-infrared data from the Keck Observatory in Hawaii show that the remote gas giant was formed at the same time as its host star and managed to survive when the hydrogen fusion process at the star's core stopped.

The findings provide evidence that planets can survive the giant phase of their host star's evolution, and supports the projection that over half of white dwarfs are predicted to have similar planetary companions, the researchers said.

"This system is evidence that planets around white dwarfs can survive the giant and asymptotic giant phases of their host's evolution, and supports the prediction that more than half of white dwarfs have Jovian planetary (gas giant) companions," the paper says.

The dying star in question sits around 2.0 kiloparsecs (6,500 light years) from the Earth towards the centre of our Galaxy. The authors argue their evidence shows a likely scenario for the end stages of the Sun and how Jupiter may survive it in our own Solar System.

Anyone optimistic enough to believe humans will survive long enough to witness the death of our nearest star will need to hope we have in the meantime figured out how to also live on an inhospitable gas giant with a gravitational force 2.5 times that of Earth. ®

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