Stars, just like humans, go through different stages of life, from birth to middle age through senescence. Right now, the sun in our solar system is in its yellow dwarf phase of life – essentially middle-aged for a star in its class.
But this will not always be the case. Earth’s sun is about 4.5 billion years old, but in five billion years the sun will eventually run out of hydrogen. After that, it will develop into a red giant and engulf many inner planets, and possibly spoil the orbits of the outer planets. (Scientific models are in conflict over exactly which planets will be engulfed and how the orbits might be adjusted.) After expansion, the sun will contract until it becomes a white dwarf, at which point it will no longer produce. heat by itself, and slowly cool down for all eternity. Nothing in the universe lives forever.
While humans on Earth won’t be around to see what happens at the end of the sun’s life, other star systems in the universe can theoretically provide a glimpse into the future of our solar system – if only we could find one that was quite similar to ours.
Now, it seems, astronomers have done it. In a new study published in the Nature magazine Last week, astronomers observed the first planetary system that looks like the future path of our own solar system. What they found is that even after the sun dies, there may be surviving planets that remain.
Using the WM Keck Observatory in Hawaii, astronomers observed a Jupiter-like planet circling around a white dwarf near the center of the Milky Way. The planet in question is about 40 times more massive than Jupiter.
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“This evidence confirms that planets orbiting at a sufficiently large distance can continue to exist after the death of their star,” said lead author of the study, Joshua Blackman, a researcher at the University of Tasmania in Australia. , in a press release. “Since this system is an analogue of our own solar system, this suggests that Jupiter and Saturn could survive the red giant phase of the Sun, when it runs out of nuclear fuel and self-destructs.”
This is quite a remarkable find considering the violence that coincides with the death of a yellow dwarf star like our sun. When a yellow dwarf burns all the hydrogen in its nucleus, it turns into a giant red star. From there he collapsed into a very pale white dwarf. The small size of white dwarfs is part of the reason why it has been so difficult to detect a planetary system orbiting a white dwarf so far.
But while this may be good news for the outer gas giants, does it mean that Earth could survive the sun’s death?
“The future of Earth may not be so rosy because it is much closer to the Sun,” said co-author David Bennett, senior researcher at the University of Maryland and the Goddard Space Flight Center in The NASA. “If humanity wanted to move to a moon of Jupiter or Saturn before the Sun sintered the Earth during its red supergiant phase, we would still orbit the Sun, although we could not rely on heat. of the Sun like a white dwarf for a very long time. “
The team of scientists used a technique called a gravitational microlens to confirm their observations. In his theory of general relativity, Albert Einstein predicted that objects of great mass, like black holes or stars, would distort the space-time around them. Therefore, the light bends and warps around these massive objects. Sometimes this benefits astronomers, as objects generally too far away or too dark to be observed directly can be briefly magnified by passing huge astrophysical bodies from our perspective on Earth. Such observations are known as gravitational microlens events. This is not a common way to observe exoplanets or planets from other solar systems; as Salon previously reported, only 2% of the exoplanets discovered were found via the microlens.
In this case, astronomers tried to search for the planet’s host star and were surprised to find that its starlight was not bright enough to make an ordinary main sequence star. This helped rule out the possibility that the host star was anything other than a white dwarf.
âWe were also able to rule out the possibility of a neutron star or a black hole host. This means that the planet is orbiting a dead star, a white dwarf,â said the co-author Jean-Philippe Beaulieu, professor of astrophysics at the University of Tasmania. “It offers a glimpse of what our solar system will look like after Earth’s demise, caused by the cataclysmic demise of our Sun.”