麻豆淫院

In the hunt for extraterrestrial life, we usually look for planets orbiting sun-like stars and icy moons. But there is another possible candidate鈥攑lanets circling white dwarfs, the hot, dense remnants of dead stars.

A white dwarf is what is left when a star like our sun runs out of fuel and sheds its outer layers. Smaller and dimmer than they were before, these stellar remains have a habitable zone (a region where liquid water can exist on a planet's surface) within a few million kilometers of the star, which is extremely close in astronomical terms.

While large planets have been found orbiting white dwarfs, scientists previously thought that life could not exist on them due to tidal forces. These forces are increased when a companion planet nearby stretches the habitable planet's orbit into an oval shape. This stretches and compresses the planet's interior, generating frictional heat that can trigger a deadly greenhouse effect, making the planet uninhabitable. It would boil away any surface lakes and oceans and prevent life from forming.

However, using computer simulations, Eva Stafine and Juliette Becker at the University of Wisconsin鈥揗adison showed that Einstein's general relativity (GR) theory, which describes how gravity works at very large scales and high speeds, can stabilize a planet's orbit.

They found that the white dwarf's powerful gravity causes the planet's orbit to slowly spin. The force prevents the oval shape of the orbit from growing too large despite the gravitational tug from a companion planet. This keeps tidal heating low and would therefore preserve liquid water on the surface, potentially making it habitable.

The researchers ran simulations with and without the effects of GR. These confirmed that without GR, most habitable zone planets with nearby companion planets would be overheated and uninhabitable. However, with GR, the habitable zone is significantly larger, which avoids the runaway greenhouse effect.

Implications for future missions

"Our findings demonstrate that GR can act as a dynamical shield in compact post鈥搈ain-sequence planetary systems. This protective role should be incorporated into future habitability assessments for planets around white dwarfs," wrote the researchers in their posted on the arXiv preprint server.

Doing so will give us a greater number of options when searching for habitable planets beyond our solar system. This new research could help astronomers prioritize the most promising targets for advanced platforms, such as the James Webb Space Telescope, the largest and most powerful telescope launched into space.

漏 2025 Science X Network