Astronomers told about the exoplanet that survived the death of its star
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- Astronomers told about the exoplanet that survived the death of its star
About 5 billion years later, the Sun will exhaust its hydrogen reserves, turn into a red giant, and then shrink to a white dwarf. For a long time, astronomers believed that this process would be the end for most of the nearby planets. However, new observations by the James Webb Space Telescope (JWST) have shown that some planets can survive the death of their star. Moreover, after that, their story can only begin. About the discovery that scientists have made and why it allows us to take a fresh look at the distant future of the Solar system - in the material of Izvestia.
A world that survived the death of its Sun
The new study focuses on the exoplanet WD 1856 b, located about 80 light-years from Earth. It was first discovered back in 2020, but even then it baffled astronomers. The gas giant, about the size of Jupiter, orbits a white dwarf, the dense core of a star that has completed its evolution. At the same time, the planet itself is so close to its star that it makes a complete revolution in just 1.4 days.
The problem was that this arrangement seemed impossible. Before turning into a white dwarf, the star had to go through the stage of a red giant, having increased by almost a hundred times. At this stage, it would inevitably swallow up all the nearby planets. Therefore, scientists tried to understand: how did WD 1856 b manage to survive the death of its star in the first place?
Christopher O'Connor, an astronomer at Northwestern University in Illinois and co-author of the study
The main question is how the white dwarf 1856 b ended up where it is today, and there are two theories. One of them is that the planet was swallowed up by a dying star and managed to survive inside. Another theory is that migration occurred due to the gravitational influence of other objects in the system. The white dwarf is part of a triple star system, and the companion stars may have influenced the orbit of the 1856 b white dwarf.
Traces of the disaster preserved in the atmosphere
To understand the history of the unusual system, the researchers used the capabilities of the JWST space telescope. It allowed for the first time to study the planet's atmosphere in detail, determine its mass and temperature, and trace the possible history of its movement.
It turned out that WD 1856 b is much hotter than a planet illuminated only by a dim white dwarf should be. Its temperature reaches about 127 degrees Celsius, which is almost 240 degrees higher than expected.
Comparing the data obtained with models of cooling of gas giants, astronomers came to the conclusion that the planet was not at all near the star at the time of its death. On the contrary, it orbited at a safe distance and only 3-5.5 billion years after the star turned into a white dwarf, it began to gradually shift into the system. As O'Connor explained, as the planet moved closer to the white dwarf, the interaction with its powerful gravitational field significantly warmed it up. Since then, it has been gradually cooling down.
What one exoplanet told us about the future of the Sun
The main value of the discovery lies not at all in the WD 1856 b itself. This system has actually become a kind of model of what could one day happen to our own star system.
In about 5 billion years, the Sun will also turn into a red giant. Mercury and Venus will almost certainly be destroyed, and the fate of the Earth is still the subject of scientific debate. However, scientists understood much less what would happen to the more distant planets — Jupiter, Saturn, Uranus and Neptune.
Ryan McDonald, lead author of the study from the University of St. Andrews in the UK
We're used to looking into the past with telescopes, but this is the first time we can look into the future and see what might happen to the outer planets around the remnant of a Sun-like star. It's like using a time machine to look into the distant future of our solar system.
In addition, for the first time, the JWST telescope detected methane and small cloud particles in the atmosphere of a planet orbiting a white dwarf. This opens up a completely new field of research: now scientists will be able to study not only such worlds themselves, but also how their atmospheres change billions of years after the death of their parent stars.
Not the end, but a new beginning.
Until now, it was believed that the death of a star practically puts an end to its entire planetary system. However, a new study shows a much more complex picture. It turns out that some planets are able not only to survive this catastrophic stage, but also to continue their evolution for billions more years.
Ryan McDonald
This is just the beginning of our exploration of planets orbiting dead stars using the JWST telescope, and the search for other planets orbiting white dwarfs continues. Our results show that the death of a star is not the end: some planets are experiencing a bright and eventful future after the death of their star.
That is why astronomers consider WD 1856 b not just an unusual exoplanet, but the first real evidence that planetary systems can remain active much longer than previously thought. This means that the history of stars and their planets does not end at all when the sun itself goes out.
Переведено сервисом «Яндекс Переводчик»
