The exciting discovery of a giant nearby exoplanet has researchers wondering about the possibility of finding the first trace of extraterrestrial life.
The massive super-Earth is located 40 light-years away from our home planet, in the Cetus ("Sea Monster") constellation, and has been dubbed the "best place to look for signs of life beyond the solar system."
Telescopes around the world, including the HARPS instrument at La Silla operated by the European Southern Observatory (ESO), picked up the newly discovered planet and found it to be orbiting the habitable zone of a red dwarf star, known as LHS 1140.
The finding was detailed in a study, featured April 19 in the journal Nature.
"We could hardly hope for a better target to perform one of the biggest quests in science — searching for evidence of life beyond Earth," said lead author Jason Dittmann, from the Harvard-Smithsonian Center for Astrophysics (Cambridge, USA).
This Joint Has A Pretty Cool Atmosphere. Literally
The nearby super-Earth is huddled right next to its feeble red dwarf, so close that it only takes it 25 days to complete a full orbit. However, although it sits 10 times closer to its star than Earth to our sun, it only receives about half the warmth our planet enjoys, making for an uncomfortably chilly world.
This is because red dwarfs are much smaller than the sun and give off substantially less heat. Classified as an M dwarf star, this particular star is one-fifth the size of the sun.
However, though considerably chilly, the exoplanet has been deemed temperate enough to support life. The new planet is rocky — much like our Earth, albeit much larger — and is situated in the liquid water zone of the star.
Named LHS 1140b, after its star, the planet has likely retained most of its atmosphere due to "its large surface gravity and cool insolation." According to an ESO news release, this makes it one of the most anticipated candidates for follow-up atmospheric studies.
Astronomer Nicola Astudillo-Defru, from the Geneva Observatory in Switzerland and one of the researchers who worked on the study, explains the presently seen conditions offered by the red dwarf are "particularly favorable" and could make the super-Earth capable of sustaining life.
"LHS 1140 spins more slowly and emits less high-energy radiation than other similar low-mass stars," points out Astudillo-Defru.
The New Alien Planet Is Rocky And Enormous
To spot the new exoplanet, researchers initially used the transit method, looking at the light from its star and trying to measure subtle dips in its intensity, typically produced by a passing planet.
Sometimes, telescopes can capture the sliver of sunlight passing through the planet's atmosphere, revealing information about the atmospheric chemical composition.
In their search for alien life, researchers have analyzed numerous other potentially habitable Earth-like planets, such as Proxima b — the nearest planet to our solar system, residing at a distance of just 4.2 light-years — or the planets found in the TRAPPIST-1 system.
However, these planets don't transit their parent star as seen from Earth, so their atmospheres can't be observed through the same method.
To better understand LHS 1140b's atmosphere, the team used HARPS to undertake a precise measurement of the new planet's density and deduce its mass.
Their estimates reveal the exoplanet is at least 5 billion years old and 18,000 kilometers (or around 11,184 miles) in diameter, almost 1.4 larger than that of Earth.
The giant mass of the new planet — around seven times larger than the Earth — and the subsequent much higher density led researchers to believe LHS 1140b is probably made of rock with a dense iron core.
"What's great about having a density ahead of an atmospheric study is that this density tells you how tightly the planet holds on to its atmosphere (the atmospheric scale height)," Dittmann said in a statement.
To better ascertain whether the alien planet can harbor life, NASA's Hubble Space Telescope is due to evaluate the exact level of high-energy radiation LHS 1140b receives from its star — which, just like other red dwarfs — has been known to be quite violent in its early years.