Astronomers believe the newly discovered world LHS 1140b is one of the most promising places to search for alien life, a new study published in the journal Nature reports.
The exoplanet sits in the habitable zone of a faint red dwarf star, dubbed LHS 1140, in the distant constellation Cetus. While the world is 10 times closer to its star than Earth is to the sun, it gets only about half as much sunlight. In addition, the planet passes in front of its star once per orbit every 25 days.
Those traits suggest that the planet could potentially support life.
“This is the most exciting exoplanet I’ve seen in the past decade,” said lead author Jason Dittmann, a researcher at the Harvard-Smithsonian Center for Astrophysics, according to Phys.org. “We could hardly hope for a better target to perform one of the biggest quests in science—searching for evidence of life beyond Earth.”
When red dwarfs are young, they emit radiation that can damage the planets around them. This means LHS 1140b could once have had a magma ocean that lasted millions of years. The heat from such an ocean could have poured steam into the atmosphere. Then, when the host star cooled down it would have replenished the planet with water.
Researchers first found the body with the MEarth facility, which detected dips in light as the exoplanet passed in front of its star. They then made follow-up observations with the ESO’s HARPS instrument that showed them the world’s orbital period as well as its mass and density.
Scientists estimate the exoplanet is at least five billion years old. They also found that its diameter is 1.4 times larger than the Earth and a mass seven times greater. This suggests the world is likely made of rock and has a dense iron core.
In order to host life as we know it, a planet must have liquid surface water and be able to retain an atmosphere. There is a chance that LHS 1140b is capable of both, making it one of the best candidates to study the properties of worlds within the habitable zone.
“M dwarfs are the most common type of star in the galaxy, and the discovery of LHS 1140b provides us with an excellent opportunity to learn more about whether planets orbiting these stars are habitable,” said Victoria Meadows, a professor of astronomy at the University of Washington, who was not involved in the research, according to Space.com. “If planets like LHS 1140b orbiting M dwarfs can be habitable, then it will increase the potential prevalence of life throughout the galaxy.”