An international team of researchers, including astronomers from the University of Sheffield, have discovered a planet orbiting around a dying star in our galaxy that could potentially harbour life. The star, a white dwarf named WD1054-226, is around 117 light years from Earth.
The researchers spent 18 days recording light changes in the white dwarf at the La Silla Observatory in Chile using ULTRACAM, a high-speed astrophysics camera developed at the University of Sheffield. Although the planet cannot be observed directly, the regular passage of small moons blocking out the star’s light every 23 minutes points to the presence of a gravitational influence that could only be created by a large planet. What’s even more exciting is that this planet resides within the white dwarf’s habitable zone, making it a contender in the search for extraterrestrial life in our galaxy.
The habitable zone is a theoretical range of distances from a star where liquid water could exist on a planet’s surface. Too close to a star and the planet’s water would simply evaporate; too far away and it would freeze. The habitable zone around our Sun encompasses Venus, Earth and Mars. The white dwarf WD1054-226’s habitable zone is a lot nearer and narrower to the dying star, as it emits much less heat than our Sun.
White dwarf is the name given to the final life stage of a small-to-medium-sized star as it cools, eventually becoming a black dwarf. The cooling time of white dwarf is longer than the estimated age of the universe, therefore theoretically no black dwarves should yet exist. Larger stars, sometimes called supergiants, never become white dwarfs, instead exploding in a phenomenal and beautiful event called a supernova, the precursor to both neutron stars and black holes.
Sheffield Professor Vik Dhillon said: “Our Sun will become a red giant and then a white dwarf in a few billion years’ time, and hence our observations provide us with an opportunity to study the possible fate of the planets in our solar system.”
The international team’s observations are the first time a planet-like object has been found in the habitable zone of a white dwarf. Will we ever be able to travel far enough to reach the planet? Only time will tell.
