One of the things that fascinate astronomers and physicists the most is the discovery of planets or other celestial bodies that can be a good candidate to support life. And just yesterday, the European Southern Observatory (ESO) confirmed the presence of a super-Earth exoplanet, called LHS 1140B, that orbits around a faint red dwarf star in the constellation of Cetus. The paper detailing the discovery is published on April 19, 2017, issue of Nature.
[Image Source: MEarth Harvard University]
The LSH 1140B
This new super-Earth exoplanet was initially detected by the MEarth facility from the Harvard Center for Astrophysics. ESO's High Accuracy Radial velocity Planet Searcher (HARPS) instrument then made the crucial follow-up observations that confirmed the presence of the exoplanet. HARPS was also able to determine the orbital period of the exoplanet which provided information that helped calculate its mass and density. LHS 1140B is 6.6 times the mass of Earth which suggest it has a rocky composition because of its immense density.
LHS 1140B was discovered using the transit method. This is when an observation is made from Earth that shows a star dimming as a planet cross in front of it. As the researchers measured how much light the exoplanet blocks, they have deduced that it is about 11,000 miles in diameter, approximately 40% of Earth's size. This rocky exoplanet orbits a red dwarf that is fifth of the Sun's size and is located very near to our planet at only 40 light years away.
"This is the most exciting exoplanet I’ve seen in the past decade. We could hardly hope for a better target to perform one of the biggest quests in science — searching for evidence of life beyond Earth", expressed Jason Dittman, the lead author of the published paper from the Harvard-Smithsonian Center for Astrophysics.
[Image Source: European Southern Observatory]
Currently, the super-Earth exoplanet is perhaps the best candidate for future observations to explore and characterize its atmosphere. LSH 1140B obtains the same amount of energy from its star just like Earth does from the Sun and this is the astronomers' basis that it may possess liquid water on its surface.
"The LHS 1140 system might prove to be an even more important target for the future characterization of planets in the habitable zone than Proxima b or TRAPPIST-1. This has been a remarkable year for exoplanet discoveries", says two of the European members of the team, Xavier Delfosse and Xavier Bonfils.
The exoplanet's past
LHS 1140B may be considered as habitable now but studies suggest that the exoplanet probably had a harsh and grim past. When the red dwarf was young, it would have covered the super-Earth planet with a harsh ultraviolet glare that could have drained any water that existed in its atmosphere. That phenomenon could follow the same greenhouse effect trend that is currently visible in Venus.
Being almost seven times larger than Earth, LHS 1140B might have had a magma ocean on its surface for millions of years. The heat from natural radioactive elements suggests that it powered the, once active, ocean of lava which in turn supplied steam into the atmosphere many years after the star settled to its present, steady glow. This process could have replaced the lost surface water, giving the planet a currently habitable condition.
"Right now we're just making educated guesses about the content of this planet's atmosphere," said Dittmann. "Future observations might enable us to detect the atmosphere of a potentially habitable planet for the first time. We plan to search for water, and ultimately molecular oxygen."
Into the future
NASA/ESA Hubble Space Telescopes will conduct observations very soon to determine how much high-energy radiation is sprinkled upon the super-Earth exoplanet. This will give astronomers more details on LHS 1140B's capacity to support life.
As the developments of powerful telescopes are made, like that of ESO's Extremely Large Telescope, precise observations of many exoplanets' atmospheres can be conducted. The discovery of LHS 1140B gives astronomers a treat as it is an outstanding candidate for such studies. Because the exoplanet transits the red dwarf star, the presence of air can be examined. The future large telescopes will be able to capture subtle signals if the exoplanet's atmosphere will filter through any of the star's light as it moves in front of the star.
Sources: European Southern Observatory, MEarth, Nature