Astronomers have discovered a planet that seems to have somehow escaped the doomsday scenario. Hot Jupiter orbits a giant star that logically should swallow it, but the team has a few hypotheses about how it’s still standing. Whether it remains habitable or not, the Earth itself has a strict limit on its lifespan – in about five billion years, the Sun will run out of hydrogen fuel to burn and will instead start synthesizing helium.

This will cause it to transform into a red giant star, increasing in size and swallowing Mercury, Venus and Earth. Eventually this will blow away the outer layers of material, leaving behind a white dwarf that will slowly cool to the background temperature of space over trillions of years.

A similar fate awaits countless worlds revolving around other stars. But now astronomers have discovered a zombie planet that seems to have survived such a catastrophe no matter what. The dramatic story unfolds in a star system relatively close to Earth, only about 520 light-years away.

The lucky planet is named Halla and orbits a giant star called Baekdu in the constellation Ursa Minor. Baekdu is almost 11 times the width of the Sun, but only 1.6 times its mass, and Halla orbits fairly close to it, less than half the distance between the Earth and the Sun.

In the new study, astronomers examined the star in more detail and found that it was already melting helium, which had previously shown it to go through the red giant phase. According to his calculations, during this time, Baekdu would have moved far beyond Halla’s current orbit.

The second author of the study, Dr. “If the star depletes its hydrogen fuel, it will swell to 1.5 times the planet’s current orbital distance and completely absorb it into the process before shrinking to its current size,” said Dan Huber. . “Absorption by a star often has disastrous consequences for nearby orbiting planets. It was a complete surprise when we realized that Galla managed to survive near its giant star.”

So how did he avoid being swallowed? Scientists say that’s not the most likely explanation. Instead, they suggest that Armageddon was blocked by a second star that previously existed in the system. As the two stars aged, they would draw material from each other and prevent expansion until they finally merged into what is now Baekdu. This process does not involve growth and absorption.

Another option is that Halla didn’t stay there that long. When the two stars collided, they may have formed a cloud of gas that cooled and then formed Halla, a new “second-generation” planet in the system. Regardless, it’s an intriguing system that could teach astronomers a lot about the life and death of planets and stars. Source