Earth-like planet could orbit in dying star’s ‘habitable zone’
A recent study reveals that planetary debris, including some moon-sized objects, could indicate a rocky exoplanet in a stellar zombie’s habitable zone.
The star in question is WD1054–226, a cooling white dwarf that is the relic of a star that ran out of fuel at its core. The discovery of an exoplanet in the system would be a watershed moment for white dwarf science, astronomers say. Only one additional planet around a white dwarf has been discovered so far. However, this planet is a gas giant, comparable to Jupiter, and is not in the habitable zone.
“The possibility of a major planet in the habitable zone is exciting and also unexpected; we weren’t looking for that,” Jay Farihi, an astrophysicist at University College London and lead author of the study, said in a statement.
Fahiri warned that confirming the planet’s existence with current technology will not be straightforward. “Confirmation can come by comparing computer models with other observations of the star and orbiting debris,” he said.
Researchers have realized that a planet could be orbiting the white dwarf from “sharp dips in light” detected by the European Southern Observatory’s New Technology 3.5-meter telescope at the Observatory of La Silla in Chile. Additional observations with NASA’s planet-hunting space telescope, the Transiting Exoplanet Survey Satellite (TESS), have provided insight into why these changes in brightness may be occurring.
WD1054–226, just 117 light-years from Earth, is close enough to be directly observed by many telescopes.
Dips in brightness from WD1054–226 correspond to 65 “equidistant” planetary debris clouds orbiting the star every 25 hours, the data suggests. The regular distribution of debris in space suggests that a terrestrial planet (similar in size to Earth) could hold everything in place.
White dwarfs provide a glimpse of what will happen in our own solar system when the sun runs out of hydrogen in about five billion years. Before collapsing into disappointing white dwarfs, stars go through the so-called red giant phase. expand 100 to 1000 times and burn the planets closest to them. When the sun turns into a red giant, life on Earth will no longer be possible. Temporarily, the habitable zone will shift into the outer solar system, before shrinking again to include only the closest surroundings of the cooing white dwarf.
The theoretical planet at WD1054–226 is well within the white dwarf’s habitable region. It orbits at a distance of 1.6 million miles (2.5 million kilometers) from the parent star, about 28 times closer than Mercury is to the sun. More intriguingly, all of the debris and the possible planet must have formed or somehow arrived in the area after the red giant collapsed into the white dwarf. This is because the material is so close that it would have been devoured by the red giant.
“This orbit around the white dwarf is expected to have been cleared during the giant star phase of its life, and therefore any planet that could potentially host water and therefore life, would be a recent development. “, adds the press release. “The area would be habitable for at least two billion years, including at least a billion years in the future.”
Summary of news:
- Earth-like planet could orbit in dying star’s ‘habitable zone’
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