In the search for extraterrestrial life, scientists conducted new research which suggests that the exoplanet K2-18b could have a Super-Earth neighbor. The K2-18b orbits a star called K2-18 at around 111 light-years away from our planet Earth. While learning about the potential super-Earth exoplanet – super-Earth meaning it has a mass similar to Earth – scientists discovered that there could be another exoplanet orbiting its same parent star. The research has been published in the journal Astronomy and Astrophysics.
Two years ago, scientists discovered the planet K2-18b, which orbits a red dwarf star, K2-18, in the constellation Leo. As it was found to be located in K2-18’s habitable zone, that led scientists to believe that the planet has liquid water on its surface, which is one of the essential conditions for life that we have today. However, scientists weren’t sure whether the planet had a rocky or terrestrial surface like Earth or if it was more like a Neptune kind of planet, which consists of gas and ice.
“If you can get the mass and radius, you can measure the bulk density of the planet and that can tell you what the bulk of the planet is made of,” said Ryan Cloutier, a Ph.D. student at the University of Toronto, Canada, and who was the lead author of the research, in a statement published on Tuesday.
To perform the research, Cloutier, followed by his team of researchers, took the data from the High Accuracy Radial Velocity Planet Searcher in the European Southern Observatory’s 3.6-meter telescope in La Silla Observatory in Chile. They measured radial velocities of stars, which can reveal the existence of planets located around the measured stars.
The researchers found that the exoplanet K2-18b has a mass of between 6 and 10 times that of Earth, which results in it being either rocky, including a little gaseous atmosphere, or perhaps a water planet with a layer of ice on the top of the surface.
“With the current data, we can’t distinguish between those two possibilities,” Cloutier added. “But with the James Webb Space Telescope (JWST), we can probe the atmosphere and see whether it has an extensive atmosphere or it’s a planet covered in water.”
The James Webb Space Telescope is supposed to be a successor to the Hubble Space Telescope, and just recently it finished its test that took place in a frigidly cold chamber. It is scheduled for launch in the spring of 2019.
Scientists believe that the discovery of K2-18b’s super-Earth neighbor which also orbits the K2-18 star was a thing of good fortune. Scientists, aside from two regular signals that they received every 39 days from the star’s rotation and every 33 days from the planet’s orbit, discovered a third signal which they received every nine days, which was the first indication that there might be another planet close to K2-18b. They named it K2-18c.
“When we first threw the data on the table we were trying to figure out what it was. You have to ensure the signal isn’t just noise, and you need to do a careful analysis to verify it, but seeing that initial signal was a good indication there was another planet,” Cloutier said.