Large Earth-like exoplanet discovered in habitable zone

Elizabeth Harasym

Science and Tech Editor

Following the news of seven Earth-sized planets orbiting the nearby dwarf star TRAPPIST-1 in February is the groundbreaking discovery of an exoplanet that may exhibit the qualities necessary to support life. Jason Dittman from the Harvard-Smithsonian Center for Astrophysics led a team of his colleagues at the Cerro Tololo Inter-American Observatory in Chile where they discovered the sizeable, temperate planet, and they have published their findings in the journal Nature.

Photo courtesy of Wikimedia Commons 
AN EXOPLANET has recently been discovered orbiting a nearby red dwarf star known as LHS 1140. This planet LHS 1140b exists in the habitable zone around its star, meaning its planetary surface may support liquid-water given a certain atmospheric pressure.

An exoplanet is a planet that orbits a star outside of our solar system. This newly discovered exoplanet LHS 1140b orbits a M-dwarf star titled LHS 1140. About 12 parsecs or 41 light years-away from Earth in the constellation Cetus, LHS 1140 is a small, cool star containing roughly 15 percent the mass of the sun. The star’s current state is highly favorable because of its slower spinning and lower emission of high-energy radiation. Red dwarf stars, however, when young, are highly luminous and often emit radiation that can be damaging to the atmospheres of orbiting planets. If a planet is large enough, as is 1140b, magma could have existed on the planet’s surface for millions of years. The lava could potentially supply the atmosphere with steam until after the star cooled to its current cooler state and therefore replenish the planet’s water.

The MEarth-South survey, a series of small telescopes, was used to detect dips in starlight as the exoplanet passed in front of LHS 1140. Dittman and his colleagues determined that the planet passed in front of its star once every 25 days. A HARPS instrument or High Accuracy Radial velocity Planet Searcher collected data to confirm the planet’s presence and to determine its mass and density. From the data analysis, the researchers then designated LHS 1140b a “super-Earth” due to having a mass 6.6 times that of Earth and most likely consisting of rock with a dense iron core.  The insolation for LHS 1140b was determined to be 0.46 that of Earth’s, and thus the exoplanet is considered to be in the habitable zone in which there is the potential for liquid –water to exist. Because there is a chance that LHS 1140b has retained its atmosphere, there is a chance the planet may harbor life.

The discovery of LHS 1140b is a significant one for the study of exoplanets and their abilities to support life. Due to its relatively close proximity to Earth, LHS 1140b will be a noteworthy candidate for future studies as high-power telescopes under construction may soon be able to search for distinct atmospheric gases on the planet or for the amount of radiation the planet receives.

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