Thursday, May 13, 2021

A strange exoplanet orbiting a white dwarf gives a peek at the future of our own solar system

This illustration shows the white dwarf WDJ0914+1914 and its Neptune-like exoplanet. Since the icy giant orbits the hot white dwarf at close range, the extreme ultraviolet radiation from the star strips away the planet’s atmosphere. While most of this stripped gas escapes, some of it swirls into a disc, itself accreting onto the white dwarf. 

Using observational data and theoretical models, the researchers believe this white dwarf is 28,000 degrees Celsius, around five times the Sun's temperature. The planet orbiting it is at least twice the size of the white dwarf. The planet orbits the white dwarf in just about 10 days.

Our sun is categorized as a yellow dwarf star, and is still in the early phase of its life, generating excess energy by fusing hydrogen into helium.


 In about 5 billion years, the sun will run out of its supply of hydrogen, and, being too cool to fuse higher elements, will cease thermonuclear fusion. At that point, the sun will expand, transform into a red giant, growing hundreds of times larger and engulfing nearby planets, like Mercury, Venus and perhaps Earth. In this process, stars like the sun shed their outer gaseous layer, leaving only a hot, compact burnt-out core, known as a white dwarf. 

White dwarfs generate no energy of their own, but have enough leftover heat that they continue to radiate for trillions of year before cooling to a black dwarf — though the process of cooling takes so long that it is not believed that there are any black dwarfs in the universe currently.

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