The planet, with a mass about 1.9 times that of Earth, is orbiting a white dwarf star about 4,200 light-years away from the Solar System near the bulge in the Milky Way (our galaxy), according to a study from a telescope in Hawaii.
This information suggests that the first rocky planet discovered orbiting a white dwarf was originally located in the star’s “habitable zone.” This is the region not too hot or too cold, where liquid water can exist and potentially support life. When the star was alive and shining, the planet could have had Earth-like conditions, with the potential for liquid water and life on its surface.
Illustration of a rocky planet orbiting a white dwarf star, about 4,200 light years from Earth. Photo: Reuters
As the host star dies and becomes a white dwarf, the planet moves farther away, 2.1 times its original distance, due to the loss of mass from the star. This movement away reduces the gravitational influence of the white dwarf on the planet, causing the planet's orbit to expand.
“The planet is currently frozen because the white dwarf — the star it orbits — is much smaller and fainter than when it was a normal star,” said astronomer Keming Zhang from the University of California, San Diego, lead author of the study.
Our Sun, which is about 4.5 billion years old, will also become a white dwarf in the future. "At the end of its life, when the Sun runs out of hydrogen fuel, it will swell into a red giant, gently blowing off its outer layers in the process," explains study co-author Jessica Lu, an astronomer at the University of California, Berkeley.
As the Sun loses some of its mass, the planets around it will move farther apart in their orbits. Eventually, the Sun will be left with only a hot, dense core – a white dwarf.
Astronomers have proposed many theories about Earth's future as the Sun expands and enters its red giant phase. In about 7 billion years, the Sun will expand, potentially engulfing nearby planets like Venus.
However, the fate of the Earth remains a matter of debate. Some models predict that the Earth will be destroyed, while others suggest that the Earth could survive due to a change in its orbit.
Mars is expected to be safe, as it is farther from the Sun than Earth and Venus. According to Zhang, new models show that Earth's orbit could adjust in a similar way to the planet his team is observing. This could improve the odds of Earth surviving longer than originally thought.
So far, the planets discovered orbiting white dwarfs have been mostly gas giants, larger than Jupiter, the largest planet in our Solar System. However, there was an interesting exception when astronomers discovered a white dwarf orbited by two objects: a planet about the size of Earth and a brown dwarf, which is larger than a planet but smaller than a star.
The planet went through several extreme phases as its host star became a red giant, possibly transitioning into a lava state before cooling down to its current state. This is a testament to the dramatic changes planets undergo as their host star undergoes its death throes, according to Zhang.
As our Sun ages, the habitable zone of the solar system will shift outward, pushing Earth out of the zone in less than a billion years. At that point, Earth’s oceans will likely evaporate, leaving the planet unable to support life.
Zhang predicts that humanity, or any remaining life, will have to migrate away from Earth before the billion-year mark. He also points to several large moons in the outer solar system, such as Ganymede (Jupiter), Titan and Enceladus (Saturn), as potential refuges as the Sun enters its red giant phase. “There is still hope,” Zhang said, suggesting that humans could seek new habitats in the solar system.
Ha Trang (according to Reuters)
Source: https://www.congluan.vn/hanh-tinh-lanh-leo-nay-cho-thay-cai-nhin-ve-tuong-lai-cua-trai-dat-post314177.html
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