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TeaThe golden age of discovering planets around other stars (known as exoplanets) began in 1995. Since the first discoveries, more than 4,500 worlds have been found, most of them orbiting ordinary stars like our Sun.
The Sun is about 4.6 billion years old, and Earth and all the other planets formed at roughly the same time. But what will happen to the planets in the next 5 billion years, when the Sun will eventually die?
In A new study published in NatureIn this article, we show a glimpse into the possible future of our solar system, when the Sun burns off all its hydrogen fuel and becomes a dead star called a white dwarf.
This possible future is represented in the form of a white dwarf thousands of light-years away, placing a gas giant planet in an orbit similar to Jupiter between 2.5 and 6 times as far from its star as Earth is from the Sun.
magnifying gravity
The journey of discovery began in 2010, when the white dwarf and its Jupiter-like companion became perfectly aligned with a much more distant star in the dense star regions at the center of the galaxy.
The gravity of the white dwarf and its companion acted like a magnifying glass, bending the light from the distant star and making it appear brighter to observers on Earth. This effect, known as “gravitational microlensing”, was predicted by Einstein in 1936.
Read also: Asteroid with shortest orbital period in Solar System and human DNA seen 7,200 years ago
While the background star was magnified, the small scale of this chance event meant that we could not distinguish between the star in the foreground and the star in the background, let alone the planet.
But the details of how the background star’s magnification changes over time can be used to reveal the properties of a nearby star and its planet. So an international team of astronomers led by Goddard of the University of Tasmania and NASA headed to Hawaii to use one of the world’s largest telescopes to get a better look.
The Keck-II telescope atop the dormant Mauna Kea volcano has a 10-meter interlocking array of hexagonal mirrors and “laser-guided adaptive optics” to filter out “flaring” caused by changes in the atmosphere. We used this to obtain extremely high-resolution images of both the background and foreground stars.
However, to our surprise, we could not see the foreground star at all. Predictions from the original magnification event in 2010 indicated that this star, weighing about half that of the Sun, should be visible. But we couldn’t figure it out.
After a few years grappling with our data to make sure we weren’t making a mistake, we realized that we couldn’t see the star because it’s a white dwarf, which in this case is too hard to detect. was too faint.
dead stars
White dwarfs are Earth-sized remnants of ordinary stars like our Sun. About 95% of the stars in the Milky Way will eventually become white dwarfs.
In about 5 billion years’ time, when the Sun burns through all of its hydrogen fuel, it will become a red giant in size, likely destroying Mercury and Venus in the process. Earth could also be destroyed, or at least severely disrupted; If by some miracle the human race continues to exist until then, our distant descendants will have to go out into the world to survive.
In the red giant phase, the Sun can delay its inevitable collapse by burning heavy atoms such as helium. However, this relief would only last for 100 million years or so.
When these heavy fuels run out, the Sun will fall into its final white dwarf state. In the collapse, the Sun will blow off half its mass as a cloud of hot gas and push the surviving planets into a wider orbit.
For planets, there is a fine balancing act between being ingested during the expansion of a red giant and possibly ejected into deep space when a white dwarf becomes. Our discovery reveals what some theorists have predicted: that planets in wide orbits are likely to survive the death of their host star.
Since most stars end up as white dwarfs, we don’t have a precise estimate of when this system formed. However, statistics support the origin as a star that is not much different in mass from the Sun.
The universe is not old enough that stars that are about 80% smaller than the Sun have evolved into white dwarfs, and stars more than nearly twice the size of the Sun are intrinsically rare and even more likely to experience more turbulent deaths. would destroy their planetary systems.
We hope to learn more about the system by directly measuring the incredibly faint residual light emitted by this dead Sun, using the Hubble Space Telescope or its successor, the James Webb Space Telescope (due to launch in December 2021) .
read also: Earth is getting dimmer and a bacteria that could help farming on Mars
Joshua W Blackman, astronomer, University of Tasmania And Andrew A. ColeAssociate Professor in Astrophysics University of Tasmania
This article is republished from Conversation Under Creative Commons license. read the original article.
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