Dying star may provide preview of Earth's doomsday

Using the world's most powerful radio telescope, astronomers have observed an old dying star - located 208 light years away - that may provide a glipmse of how planet Earth will end in a few billion years' time.
Astronomers set out to look for answers in the ten billion year old star L2 Puppis. Five billion years ago, this star was very similar to the Sun as it is today.
"Five billion years from now, the Sun will have grown into a red giant star, more than a hundred times larger than its current size," said Leen Decin, Professor at the KU Leuven Institute of Astronomy in Belgium.

"It will also experience an intense mass loss through a very strong stellar wind. The end product of its evolution, seven billion years from now, will be a tiny white dwarf star," said Decin.
"This will be about the size of the Earth, but much heavier: one tea spoon of white dwarf material weighs about five tonnes," she said.
This metamorphosis will have a dramatic impact on the planets of our solar system. Mercury and Venus, for instance, will be engulfed in the giant star and destroyed.

"We already know that our Sun will be bigger and brighter, so that it will probably destroy any form of life on our planet," said Decin.

However, whether the Earth's rocky core will survive the red giant phase and continue orbiting the white dwarf remains a question, she added.
To answer this question, astronomers observed the evolved star L2 Puppis. This star is 208 light years away from Earth - which, in astronomy terms, means nearby.
The researchers used the ALMA radio telescope, which consists of 66 individual radio antennas that together form a giant virtual telescope with a 16-kilometre diameter.
Schematic representation of the candidate planet's orbit in the disk around L2 Puppis.
"We discovered that L2 Puppis is about 10 billion years old," said Ward Homan, from KU Leuven Institute of Astronomy.

"Five billion years ago, the star was an almost perfect twin of our Sun as it is today, with the same mass. One third of this mass was lost during the evolution of the star. The same will happen with our Sun in the very distant future," said Homan.
About 300 million kilometres from L2 Puppis - or twice the distance between the Sun and the Earth - the researchers detected an object orbiting the giant star.
In all likelihood, this is a planet that offers a unique preview of our Earth five billion years from now.
A deeper understanding of the interactions between L2 Puppis and its planet will yield valuable information on the final evolution of the Sun and its impact on the planets in our Solar System.

Whether the Earth will eventually survive the Sun or be destroyed is still uncertain. L2 Puppis may be the key to answering this question, researchers said.