An international team of scientists have recently discovered a "super-Earth" planet orbiting a relatively calm red dwarf star forty light years away in the constellation of Cetus they say is an optimal target to study for evidence of life beyond our own planet.
A super-Earth is a planet that has more mass than the Earth, but substantially smaller than one of the gas giants in our solar system (usually the upward bound is about ten Earth masses). Calling it a super-Earth, however, doesn't mean it is anything like the Earth in other ways. Super-Earths can have completely different surfaces, temperatures, atmospheres, and don't have to be inhabitable. Scientists have deduced that this new planet is about one and a half times the size of Earth, but is seven times more massive, and therefore more dense. This means we can infer that the planet has a rocky core, most likely made of iron.
How could scientists figure out the mass and density of a planet so far away, that we can't really see or observe in the same way we can planets in this solar system? Scientists used equipment at the MEarth facility to detect the dips in light as the planet passes in front of its star. Using this information, as well as measurements from the European Southern Observatory's HARPS (High Accuracy Radial velocity Planet Searcher) instrument, they can deduce the orbital period of the planet, and use these measurements to figure out what size planet would travel at that speed and at that distance from the star. These numbers, however, are deductions. They are the best, closest guesses scientists can make with the information they have available.
This newly discovered planet (LHS 1140b) is considered a possible candidate to host life, since it exists in the habitable zone around its faint red star. This means that it is in an orbit range where liquid water could exist on the planet's surface, though in this planet's case, that might not always have been true. Over forty million years ago, the planet would have been bombarded with radiation fluctuations from the star when it was younger, and its water may have evaporated, causing a runaway greenhouse effect like we see on Venus today. Now, however, the red dwarf star has settled down and has much steadier emissions, leading to a more consistent temperature range for the planet.
"The present conditions of the red dwarf are particularly favorable--LHS 1140 spins more slowly and emits less high-energy radiation than other similar low-mass stars," says Nicola Astudillo-Defru from Geneva Observatory in Switzerland.
Of course, just because a planet CAN have liquid water and COULD host life doesn't mean it does. So many factors go into the formation of life that we know very little about it. Any fluctuation could make a similar system have drastically different results as far as life is concerned. And we don't even know if all life requires the same "recipe" of conditions in all cases. Planets like LHS 1140b will prove valuable in our research into this subject. The more planets we find to study, the better.
"This is the most exciting exoplanet I've seen in the past decade," Jason Dittman of the Harvard-Smithsonian Center for Astrophysics says. "We could hardly hope for a better target to perform one of the biggest quests in science--searching for evidence of life beyond Earth."
1140b is also considered a prime candidate for future studies in exoplanet atmospheric conditions on exoplanets--possibly the best yet. Because the planet is so dense, scientists believe this means it may have retained a lot of its atmosphere. And because the planet passes in front of its parent star, rather than in an orbit where we can't record observations of it, that means scientists will have an easier time studying it.
Future studies of the planet, involving NASA/ESA's Hubble Space Telescope and ESO's upcoming Extremely Large Telescope, will tell us even more about the planet's capacity for life and its atmosphere.
"The LHS 1140 system might prove to be an even more important target for future characterization of planets in the habitable zone than Proxima b or TRAPPIST-1," conclude Xavier Delfosse and Xavier Bonfils at the CNRS and IPAG in Grenoble, France. "This has been a remarkable year for exoplanet discoveries."
Melanie R. Meadors is an author of fantasy where heroes don't always carry swords and knights in shining armor often lose to nerds who study their weaknesses. A wearer of many hats, she is a blogger at The Once and Future Podcast, a professional author publicist, and a dabbling musician and artist. She studied both physics and astronomy at Northern Arizona University. You can find her at her website, melaniermeadors.com, on Facebook, and Twitter, @melaniermeadors.