A swarm of moon-sized objects has been discovered orbiting a white dwarf star, their trajectories indicating that they are held in place by a larger, unseen object. According to astronomers, this is the first planet discovered in a white dwarf’s habitable zone. The announcement is one of three surprise white dwarven finds made in a big week for dead stars. Planets orbiting white dwarves have scarcely been considered in the search for life in the universe. These stars are a shadow of their former selves, having fused their hydrogen and shed their outer layers.
Planets that formed while the star was young would have been subjected to such drastic temperature swings as the star evolved, if not completely destroyed, that any life on them would have perished long ago. White dwarfs do, however, have a close-in “habitable zone” where temperatures are suitable for liquid water, and evidence for a planet in this zone has been discovered for the first time, according to a report published in Monthly Notices of the Royal Astronomical Society.
WD1054-226, which is 117 light-years away, is the star in dispute. WD1054-226 is presently at 16th magnitude, somewhat fainter than Pluto, and is nowhere near as luminous as it would have been when it was still converting hydrogen to helium. Every 23 minutes, observations performed with the European Southern Observatory’s New Technology Telescope indicate light dips caused by objects passing in front of the star. One of the methods used by astronomers to find exoplanets is the transit method.
These dips, however, were confirmed by NASA’s planet-hunting TESS satellite telescope, which found a pattern. This led Professor Jay Farihi of University College London and co-authors to the conclusion that this is 65 clouds of debris spaced out around an orbit that sees each one pass the star every 25 hours, rather than a single object blasting around at incredible speed. Because WD1054-226 is so dim, temperatures at that orbit are suitable for liquid water.
In a statement, Farihi added, “This is the first time scientists have identified any form of planetary body in the habitable zone of a white dwarf.” On the concealing objects, there’s no prospect of liquid water, let alone life. They’re “irregular and dusty (e.g. comet-like) rather than solid, spherical things,” according to Farihi. Their seeming stability, on the other hand, could signal the presence of something broader and potentially more fascinating.
“Their incredible regularity, with one passing in front of the star every 23 minutes,” Farihi added, “is a conundrum we cannot now explain.” “A fascinating idea is that these bodies are held in such an equally spaced orbital pattern due to the gravitational pull of a neighboring planet. Without this influence, friction and collisions would cause the structures to disperse, resulting in the precise regularity that is observed.” The gravitational push of adjacent moons forms stable formations in Saturn’s rings, which is similar. As seen from Earth, the planet’s orbit does not appear to cross the face of the white dwarf, making direct confirmation by blips in light from the star impossible.
Instead, the authors seek to prove its presence by a more extensive investigation of the debris’ orbits, which would be aided by JWST data. The discovery adds to recent evidence that white dwarves can have a second set of planets after their time as a main sequence star has ended, similar to a retiree rearing a second family. White dwarfs have the ability to shine for longer periods of time than main sequence stars. They diminish so slowly over time that WD1054-habitable 226’s zone will last for 2 billion years – half of which is yet to come – potentially providing enough time for life to evolve and grow on a suitable planet.
The Sun, like the great majority of stars, will eventually turn into a white dwarf. Before then, its red giant stage will put an end to life on Earth, but WD1054-226 opens the chance that something could rise from the ashes like a phoenix near to where we are now. Metal “pollution” has been found in the spectra of many white dwarfs, which has been thought to represent evidence of recently eaten planets. For the first time, this was claimed to be observed as it is occurring last week. Just yesterday, a white dwarf enveloped in carbon and oxygen was announced, which could be the result of the merger of two white dwarves.
