The exoplanet LHS 1140 b, located 39 light-years away from Earth, may be the perfect candidate for detecting liquid water beyond our Solar System.
Scientists have discovered a super-Earth orbiting an M dwarf star, situated 39 light-years from our Solar System. They have named this rocky planet LHS 1140b and believe it may have formed in its current position similarly to Earth, according to the International Business Times.
The James Webb Space Telescope (JWST) has detected a distant planet discovered a few years ago that may contain an ocean with a width of 4,000 km, surrounded by a solid icy sea, making it a potential candidate for supporting life, as reported by Live Science. The exoplanet LHS-1140b was first discovered in 2017. Initially, researchers categorized it as a “mini-Neptune” composed of a mixture of water, methane, and ammonia. However, new findings set to be published in the Astrophysical Journal Letters indicate that this planet contains more ice and moisture than previously thought, potentially supporting life.
“Among all known temperate exoplanets, LHS-1140b may be the best option for confirming the existence of liquid water on the surface of a planet outside our Solar System in the future,” remarked the lead researcher Charles Cadieux, an astrophysicist at the University of Montreal. “This is a significant milestone in the search for potentially habitable exoplanets.”
LHS 1140b orbits a cold dwarf star. (Photo: M. Weiss/CfA).
The research has revealed that the planet LHS 1140b moves around the small cold star in a circular orbit. “We discovered this planet using the transit method. As it passes between the star and Earth, it dims the light emitted by the star, allowing us to measure the dimming and identify LHS 1140b,” said Jason Dittmann from the Harvard-Smithsonian Center for Astrophysics and the lead researcher.
Using angular-radius measurements, scientists were able to understand certain unique characteristics of the exoplanet. They calculated that the mass of LHS 1140b is 6.6 times that of Earth, making it a rocky planet similar to Earth but quite barren. This planet is tidally locked to its host star, meaning it rotates at the same rate as its orbit.
Due to its proximity to the host star, one year on LHS-1140b is only about 25 Earth days long. If LHS-1140b’s host star were a main-sequence star like the Sun, such an orbit could boil its oceans and render the planet completely uninhabitable. However, since it orbits a cool red dwarf, the close distance places the planet in the “Goldilocks zone,” the perfect area around a star for liquid water to exist on its surface.
However, new research from Dr. Charles Cadieux’s team has indicated the planet’s potential density through spectral data, showing that it cannot be solely rocky but is rich in water, possibly even more than Earth.
They also found that LHS 1140b receives light equal to 0.46 times that of Earth. In a 2013 study, another group of scientists found that a planet orbiting an M dwarf star could have surface temperatures allowing for liquid water if the incoming light is between 0.2 and 0.8 times the sunlight received by Earth.
The journey from Earth to LHS 1140b.
LHS 1140b is located in the habitable zone, the region surrounding the host star where rocky planets are most likely to have liquid water. This discovery is quite remarkable as LHS 1140b orbits a small cold star, which does not emit as much energy as other stars.
“Most exoplanets discovered previously orbit active stars, which can affect the stability of potential biological organisms on their surfaces. The star that LHS 1140b orbits appears to be quite calm, so it will not destroy the atmosphere or anything on the planet’s surface,” Dittmann explained.
“The next step is to determine whether this planet has an atmosphere and to search for Earth-like features such as oxygen, CO2, ozone, and water. We will need to study the planet’s atmosphere before concluding whether life could exist there,” Dittmann added.
Planet LHS 1140b and its hazy mother star – (Graphic: ESO).
The Canadian team of scientists even suggests that LHS 1140b is a top target for the search for extraterrestrial life, even more so than TRAPPIST-1, a star system with seven planets, all of which have some Earth-like features.
However, the research team believes that three planets in the habitable zone of TRAPPIST-1 may be too barren relative to hopes, lacking atmospheres and surface water.
The host star TRAPPIST-1 is overly active, producing many flares that can devastate the atmospheres of nearby planets.
In contrast, the star LHS-1140 is much less active than both TRAPPIST-1 and the Sun, allowing the planet LHS 1140b to remain safe despite its proximity to the host star, at a distance only a quarter that of Mercury to the Sun.
Scientists are still hopeful for the James Webb Space Telescope—the most powerful space telescope in the world, jointly operated by American, European, and Canadian space agencies (NASA/ESA/CSA).
James Webb cannot directly see any life forms existing on that planet, but it is powerful enough to deeply reveal the chemical composition of LHS 1140b’s atmosphere, thereby helping to answer the question of whether it is truly filled with life.
