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Big Milestone-- A Giant Planet Orbiting Close to a Dead White Dwarf Star!!!


Artist's illustration of WD 1856 b, a potential Jupiter-size planet, orbiting its much smaller host star, a dim white dwarf. (Image credit: NASA’s Goddard Space Flight Center)

A big milestone to the Astronomical history. A team of Astronomers have spotted signs of an intact giant planet circulating around a superdense stellar corpse known as a white dwarf, a new study reports.

An international team of astronomers using NASA’s Transiting Exoplanet Survey Satellite (TESS) and retired Spitzer Space Telescope has reported what may be the first intact planet found closely orbiting a white dwarf, the dense leftover of a Sun-like star, only 40% larger than Earth.

What is a white dwarf

The white dwarf in question, called WD 1856, is part of a three-star system that lies about 80 light-years from Earth. White dwarfs are thought to be the final evolutionary state of stars whose mass is not high enough to become a neutron star, that of about 10 solar masses. The smaller stars began to swell during the end of their life to get bigger in size. This swelling leads to them becoming a red giant. As they do this, their outer layers peel off and drop, similar to shedding. The star begins to collapse and fall in on itself as its fuel begins to run low. Once the star is done shedding its body’s layers, then all that will be left behind is the star’s core. The core that is left behind is the white dwarf.

What is an Exoplanet

All of the planets in our solar system orbit around the Sun. Planets that orbit around other stars are called exoplanets. Exoplanets are very hard to see directly with telescopes. They are hidden by the bright glare of the stars they orbit. The Exoplanet of Jupiter-size, called WD 1856 b, is about seven times larger than the white dwarf, named WD 1856+534. It circles this stellar cinder every 34 hours, more than 60 times faster than Mercury orbits our Sun. 

How can the Exoplanet survive the evolution of White dwarf

 The planet is located just 4 solar radii from the white dwarf (or roughly 20 times closer to the white dwarf than Mercury is to the Sun). Assuming that the inner planetary system was swallowed by the expanding star, it seems extremely unlikely that the planet has always been this close to its star.

“WD 1856 b somehow got very close to its white dwarf and managed to stay in one piece,” said Andrew Vanderburg, an assistant professor of astronomy at the University of Wisconsin-Madison. “The white dwarf creation process destroys nearby planets, and anything that later gets too close is usually torn apart by the star’s immense gravity. We still have many questions about how WD 1856 b arrived at its current location without meeting one of those fates.”

The researchers believe the planet was much further away from its host star and migrated closer after the star evolved. Their simulations suggested that when the star became a white dwarf, the planet was kicked closer in. The study suggested a theory that large planets can survive the violent evolution of a star and arrive at a close orbit around it afterward.

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