The discovery of an Earth-like planet 4,000 light-years away in the Milky Way provides a preview of a possible fate for our planet billions of years from now.
By then, the Sun will have become a white dwarf and the frozen, devastated Earth will have moved beyond the orbit of Mars.
This distant planetary system was identified by astronomers at the University of California, Berkeley, after observing it with the Keck 10-meter telescope in Hawaii. Looks very similar to expectations for the Sun-Earth system: It has a white dwarf with half the mass of the Sun and an Earth-sized companion in an orbit twice the size of Earth today.
That is likely to be Earth's fate. The Sun will eventually blow up in a balloon larger than Earth's orbit todayEngrossing Mercury and Venus in the process.
As the star expands into a red giant, its mass loss will cause the planets to migrate to more distant orbits, giving Earth a small chance to survive further from the Sun.
Eventually, the outer layers of the red giant will disappear, leaving behind a dense white dwarf no larger than a planet, but with the mass of a star. If Earth had survived by then, it would have ended up in an orbit twice its current size.
The finding, published in the journal natural astronomy, It informs scientists about the evolution of main sequence stars, such as the Sun, through the red giant phase to become a white dwarf and how that affects the planets around them. Some studies suggest that, for the Sun, this process could begin in about a billion years, eventually evaporating Earth's oceans and doubling Earth's orbital radius, if the expanding star doesn't engulf our planet first.
Finally, within about 8 billion years, The outer layers of the Sun are scattered And they leave behind a dense, bright ball, a white dwarf, about half the mass of the Sun but smaller than Earth.
“We don't have a consensus on whether Earth can avoid being engulfed by a red giant sun in 6 billion years,” Keming Zhang, a former postdoctoral fellow at the University of California, Berkeley and now a postdoctoral fellow at the University of California San Diego, said in a statement.
Billions of years of life
“Anyway, planet Earth will only be habitable for another billion years. “At that point the Earth's oceans will evaporate from the runaway greenhouse effect, long before it risks being swallowed up by the red giant.”
Planet Earth will only be habitable for another billion years.
Although a dim white dwarf is outside the habitable zone and unlikely to harbor life, the planetary system provides an example of a planet that has survived. It may have once had habitable conditions when its host was still a Sun-like star.
“It is not known whether life can survive on Earth during that (red giant) period, but the most important thing is that the Earth will not be swallowed up by the Sun when it becomes a red giant,” said Jessica Lu, associate professor. Chair of Astronomy at the University of California, Berkeley. “This system discovered by Kemming is an example of a planet (perhaps an Earth-like planet that originally had an Earth-like orbit) that survived the red giant phase of its host star.”
Discovered by a small incident
Astronomers have caught the attention of a distant planetary system located near the bulge at the center of our galaxy, which could be habitable for only another billion years. 2020 it passes in front of a distant star and magnifies that star's light by 1,000 times. The system's gravity acted as a lens, focusing and amplifying the light from the background star.
The team that discovered this “microlensing event” named it KMT-2020-BLG-0414 because it was detected by the Korea Microlensing Telescope Network in the Southern Hemisphere. Magnification of the background star (also in the Milky Way, but about 25,000 light-years from Earth) is a tiny light.
However, due to its intensity variation of about two months, it has been estimated that the system includes a star with half the mass of the Sun, a planet about the mass of Earth, and a very large planet 17 times the mass of Jupiter (probably a brown dwarf). Brown dwarfs are failed stars with a mass just below the initiation of fusion at the core.
The analysis concluded that the Earth-like planet is between 1 and 2 AU from the star (that is, twice the distance between Earth and the Sun). It is not clear what kind of star the host is because its light is lost in the brightness of the massive background star and some nearby stars.
