Astronomers have recently declared that they have discovered eight new planets in the Goldilocks region of their stars, circling at a distance where liquid water can possibly exist on the planet’s surface. This recent discovery also doubles the number of small planets supposed to exist in the habitable region of their parent stars. Among these eight newly discovered planets, the group discovered two planets that are the most similar to our Planet Earth of any identified exoplanets to date. These results were declared recently in a press conference at a summit of the American Astronomical Society. The two best Earth-like of the recently discovered planets are Kepler-438b and Kepler-442b. Both circle red dwarf stars that are not just minor but also cooler than our Sun. Kepler-438b orbits its star every 35 days, although Kepler-442b ends one orbit in every 112 days. With a diameter just 12% greater than Earth, Kepler-438b has a 70% possibility of being rocky, according to the group’s calculations. Kepler-442b is roughly one-third bigger than Earth, but still has a 60% possibility of being rocky. In order to be in the habitable region, an exoplanet must get nearly as much sunlight as Earth. Too much sunlight and any water present on the surface would boil away as steam. Too little sunlight and water present on the surface will freeze solid.
|Artist's Illustration of a planet orbiting an older, more evolved star (Image Credit: David A. Aguilar (CfA)|
Kepler-438b gets almost 40% more sunlight than Earth. In comparison, Venus receives twice as much solar radiation as Planet Earth. So as a result, the group calculates it has a 70% chance of being in the habitable region of its parent star. Kepler-442b receives about two-thirds as much light as Planet Earth. The researchers give it a 97% chance of existence in the habitable region. Second author David Kipping of the CfA explains “We don’t know for sure whether any of the planets in our sample are truly habitable. All we can say is that they’re promising candidates.”
Earlier than this, the two most Earth-like exoplanets identified were Kepler-186f, which is nearly 1.1 times the magnitude of Earth and gets 32 percent as much light, and the second one was Kepler-62f, which is nearly 1.4 times the size of Earth and receives 41% as much light. The group studied planetary candidates first discovered by NASA’s Kepler mission. All of the planets were way too small to approve by measuring their masses. As an alternative, the group confirmed them by means of a computer program called BLENDER to conclude that they are statistically likely to be planets. BLENDER was established by Torres and coworker Francois Fressin, and works on the Pleaides supercomputer at NASA Ames. This is the similar technique that has been used earlier to confirm some of Kepler’s most iconic discoveries, counting the first two Earth-size exoplanets orbiting a Sun-like star and also the first exoplanet smaller than Mercury.
After the BLENDER analysis, the group used up another year collecting follow-up observations in the kind of high-resolution spectroscopy, adaptive optics imaging, and speckle interferometry to carefully describe the systems.
Those follow-up observations also exposed that four of the recently confirmed planets are in multiple-star systems. Though, the companion stars of these systems are away and don’t considerably effect the planets.
As with several Kepler findings, the recently discovered planets are distant enough to make further observations puzzling. Kepler-438b is situated 470 light-years from Planet Earth while the further distant Kepler-442b is 1,100 light-years away.