A planet can be found in the habitable zone around the dead star. will be the first.
White dwarfs are the smoldering remnants of stars that have used up all their hydrogen – their fuel. Almost all stars, including our Sun, will eventually turn into a white dwarf. However, it is still unknown what will happen to planets – such as our Earth – orbiting these “dead stars” in this case. But New study Provides a glimpse into our future.
In the study, using ULTRACAM mounted on ESO’s New Technology Telescope (NTT), the researchers examined the white dwarf star WD1054-226, located 117 light-years from Earth. To their surprise, they found a significant drop in brightness, indicating a ring of planetary debris orbiting the star, completing one orbit every 25 hours. “The structures are the size of the moon,” said study leader Jay Farihi. “In addition, they are quite dusty, possibly similar to comets. Their precise regularity, dimming the white dwarf’s light every 23 minutes, is a mystery that we cannot explain at the moment.”
However, researchers speculate wildly. In doing so, they came up with an interesting possibility. “An exciting possibility is that these celestial bodies are held in such an even orbit by the gravitational pull of a nearby planet,” suggests Varii. Without this effect, friction and collisions would lead to the disintegration of structures. And then we wouldn’t have seen the exact regularities that were observed.” Researchers compare this to the moons around Neptune and Saturn, which also contribute significantly to the stable rings we find around these planets.
It is also interesting that, according to the research team, this suspected planet could be in the habitable zone, which means that it may contain liquid water (see box). “This is the first time that astronomers have detected a planetary object in the habitable zone of a white dwarf,” Farihi said.
More about the habitable area
The habitable zone is an imaginary region around a star. Planets in this region receive enough heat from the star to prevent any water from freezing on their surface. At the same time, they also do not receive so much heat that any water on their surface evaporates. In short, planets in this region are expected to be able to harbor liquid water. Compared to a star like our Sun, the habitable zone around a white dwarf would be smaller and closer to the star because white dwarfs give off less light and therefore less heat.
The discovery of a possible planet in the habitable zone of a dead star is surprising. When the star’s dying process begins, it will first transform into a fierce red giant. This process greatly affects the planets orbiting such a star, as most of the planets will be pulled towards the star and swallowed up. So it seems unlikely that planets will survive the dying process of their parent star. This means, according to the researchers, that any planet orbiting a white dwarf may contain water and therefore life may have originated and evolved recently.
A glimpse into the future
The study also provides further insight into our fate. “Because our sun will also turn into a white dwarf in a few billion years, the study offers a glimpse into the future of our solar system,” says Farihi. Currently, astronomers believe that when our sun dies, it will swallow up Mercury, Venus, and possibly Earth. However, not all life chances may be lost. Because it happens that the planets revolving around our dead sun become habitable again.
While the discovery of a planet in the habitable zone of the white dwarf WD1054-226 is an intriguing possibility, researchers are skeptical. “It’s important to keep in mind that more evidence is needed to confirm the planet’s existence,” Farihi said. “We cannot directly observe the planet.” That’s because white dwarf stars emit much less light than our sun, for example, which makes detecting planets around dead stars a huge challenge. “We will need to compare computer models with more observations of the star and its orbiting debris to confirm our hypotheses,” Farihi concludes.
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