The sun is an angry ball of fire, working o the principles of nuclear physics and powering life on Earth. However, this giver of life will not always be this kind and there will come a time when it will expend all its hydrogen fuel. What follows then will be utter chaos.
As it exhausts its fuel, the sun, nearly five billion years from now, will become a red giant. While it will lose its life-giving powers, it will go out for one last hunt in its neighbourhood the solar system.
The Sun will engulf the inner planets, Mercury, Venus, and possibly Earth. But don’t worry, by then our civilization would have likely and hopefully long gone from the planet. Researchers, in a new study, have revealed the forces acting on a planet when it is swallowed by an expanding star.
The study submitted for publication in the Royal Astronomical Journal states that interactions of a planet or brown dwarf with the hot gas in the outer envelope of a sun-like star can lead to a range of outcomes depending on the size of the engulfed object and the stage of the star’s evolution.
The researchers performed three-dimensional hydrodynamical simulations of the flow in the vicinity of a planet engulfed in a stellar envelope. They found that when the sun eats its planets it could further increase the luminosity of a sun-like star by several orders of magnitude for up to several thousand years, depending on the mass of the engulfed object and the evolutionary stage of the star.
“As the planet travels inside the star, drag forces transfer energy from the planet to the star, and the stellar envelope can become unbound if the transferred energy exceeds its binding energy,” Lead author Ricardo Yarza at the University of California, Santa Cruz explained.
However, his team did mention that since evolved stars can be hundreds or even thousands of times larger than their planets, this disparity of scales makes it difficult to perform simulations that accurately model the physical processes occurring at each scale.
His team further found that no planet smaller than about 100 times the mass of Jupiter can eject out of the envelope of a sun-like star before it has expanded to about 10 times the radius of the sun.
The results of the study can be incorporated into future work to explore the effect of engulfment on the structure of the star.
The European Space Agency recently revealed that with an age of around 4.57 billion years, the Sun is currently in its comfortable middle age, fusing hydrogen into helium and generally being rather stable. As the hydrogen runs out in its core, and changes begin in the fusion process, it will swell into a red giant star, lowering its surface temperature in the process.