Scientists Spot Hints of Potentially Habitable Planet Near Dead Star

When stars run out of their fuel and die, they often burn out and turn into white dwarfs – the remains of the stellar core, that consists mostly of electron-degenerate matter.

There could be a habitable planet in the vicinity of a white star observed by scientists from UCL, who spotted a ring of planetary debris studded with moon-sized structures orbiting close to the dead star.

The findings raise hopes that humans will find a planet with life in the so-called “habitable” zone, where liquid water – and therefore life – can exist.

“The moon-sized structures we have observed are irregular and dusty (e.g. comet-like) rather than solid, spherical bodies. Their absolute regularity, one passing in front of the star every 23 minutes, is a mystery we cannot currently explain,” said lead author Professor Jay Farihi of UCL Physics & Astronomy.

He pointed out that the discovered bodies could display an evenly-spaced orbital pattern because of the nearby planet’s gravitation. Without such influence from a possible planet, the structures would be dispersed, and the scientists would observe no regularity. A similar pattern of gravitational influence can be observed in the case of Neptune and Saturn – their “shepherding” help stabilising the ring structures around them.

“The possibility of a planet in the habitable zone is exciting and also unexpected; we were not looking for this. However, it is important to keep in mind that more evidence is necessary to confirm the presence of a planet. We cannot observe the planet directly so confirmation may come by comparing computer models with further observations of the star and orbiting debris,” he continued.

The scientific team has suggested that the orbit of the white dwarf was swept clear at the time when the dwarf was a giant star. This would indicate that the emergence of a habitable planet would be a recent development. If that’s the case, the area would be habitable for at least least two billion years.

Our Sun is among those stars which will at some point “die” by becoming a white dwarf in a few billion years. Therefore, Farihi noted, the new UCL study has somewhat provided a glimpse into the future of our own solar system.

A “white dwarf” is the end result of a star running out of hydrogen; first it expands, turning into a red giant, until nothing except the stellar core remains, then it slowly cools down over billions of years.