An inhospitable exoplanet could help astronomers narrow down the search for aliens

Astronomers discovered an Earth-like planet orbiting the most common type of star in the universe, an M dwarf.

Surprisingly, that planet appears to have no atmosphere at all, and it is completely inhospitable. Strangely enough, it's a discovery that could cause a paradigm shift by helping astronomers narrow down the search for alien life.

That's because M dwarfs are so ubiquitous. Many other planets orbiting these stars may also have no atmosphere, meaning astronomers can discount them as a possibility and reduce their search parameters for habitable planets, a press statement reveals.

A planet with no atmosphere

A group of astronomers detailed their findings on the planet, named GJ 1252b, in a paper published in the Astrophysical Journal Letters. The planet orbits its host star twice in approximately 24 hours, meaning it has a very close orbit to its star, giving it a scorching, inhospitable surface.

"The pressure from the star's radiation is immense, enough to blow a planet's atmosphere away," explained Michelle Hill, UC Riverside astrophysicist and the co-author of the study.

Earth's own atmosphere is also degraded over time by the Sun, but processes on Earth, including volcanic emissions, replenish the atmosphere at the same time.

However, if we were much closer to our Sun, we would see a similar scenario here to the one on GJ 1252b, as those processes wouldn't replenish the atmosphere quickly enough. That is exactly what happened to Mercury, in fact. The closest planet to the Sun does have an atmosphere, but it is extremely thin, thanks to the effects of our Sun.

Investigating a distant exoplanet's atmosphere

The researchers determined that GJ 1252b lacks an atmosphere by measuring infrared radiation from the planet as its light was being obscured by a secondary eclipse — one where a planet moves behind a star and the planet's light is blocked.

By measuring this radiation, the researchers were able to reveal the planet's blistering hot daytime temperatures of roughly 2,242 degrees Fahrenheit (approx. 1,230 degrees Celsius). That means gold, silver, and copper would all be liquids on the planet's surface. This heat, alongside the estimation that the planet would have a low surface pressure, led the scientists to believe it has no atmosphere.

"The planet could have 700 times more carbon than Earth has, and it still wouldn't have an atmosphere. It would build up initially, but then taper off and erode away," said Stephen Kane, UCR astrophysicist and co-author of the study.

All of this could massively alter the way scientists search for alien life on other planets. But follow-up observations from James Webb — on this planet and thousands of others — will help astronomers better understand the implications of this discovery. "If a planet is far enough away from an M dwarf, it could potentially retain an atmosphere. We cannot conclude yet that all rocky planets around these stars get reduced to Mercury's fate," Hill explained. "I remain optimistic."