Kepler's newest exoplanets may include a near-twin of Earth
Monday, June 19, 2017, 4:31 - The Kepler space telescope closes out its original four-year mission with over 200 new finds, including 10 newfound rocky, potentially life-bearing alien worlds, one of which could end up being a near-twin of Earth. It's What's Up In Space!
Scientists with NASA's Kepler mission announced on Monday that they have now completed the catalogue of the telescope's original four-year campaign of observations.
Wrapping up this chapter of the mission adds another 219 new planet candidates, 10 of which are near-Earth size and orbiting in the habitable zone - the band of space around their star where it is just warm enough for liquid water to exist on the surface of a planet.
Kepler planet candidates, plotted by size relative to Earth and length of orbit, which is a function of distance from its star. Yellow dots reflect the latest additions to the catalogue, with Earth, Neptune and Jupiter provided for comparison. Credit: NASA/Ames Research Center/Wendy Stenzel
Below is a plot showing only the small subset of relatively Earth-sized planet candidates.
Kepler habitable zone planet candidates, plotted by temperature of star and energy received from its star. Yellow dots reflect the latest additions to the catalogue, with Venus, Earth and Mars provided for comparison. Credit: NASA/Ames Research Center/Wendy Stenzel
One of the most notable new additions is known as KOI-7711, indicated by the yellow dot just to the right of Earth on the plot above (as "7711.01").
Detected in four separate transit candidates, each around 302 days apart, associated with a star that is slightly smaller and cooler than our Sun, KOI-7711 hasn't been verified as a confirmed exoplanet yet. If it is confirmed, though, it may become the most Earth-like planet in the catalogue, so far.
At just 31 per cent larger than Earth, it would most certainly be a rocky world, but with slightly higher gravity. This would make it capable of holding on to a thicker atmosphere, which usually translates into higher temperatures. Since its temperature, solely based on its distance from its star, would be around 246 Kelvin, though, or around 9 degrees cooler than Earth, this could even out to a very Earth-like environment.
Additionally, since it would have a very similar orbit to Earth around a fairly Sun-like star, it would likely rotated, just as Earth does, and not be tidally-locked (with one side always facing the star). This gives it a good chance at possessing a geomagnetic field (although some tidally-locked planets or moons may generate a magnetic field simply through tidal forces. Eg: Ganymede). If it also managed to hold on to a stable atmosphere, or at least as stable as Earth's atmosphere, it could be a prime location for the development of life!
Until KOI-7711 is verified and earns an official Kepler planet name - a process that requires a different telescope (usually ground-based) to observe it transiting - this is all speculation. This is certainly the week for exploring such ideas, however, during the Kepler Science Conference, which runs from June 19-23, at NASA's Ames Research Center in California.
The exoplanets represented in this newly updated catalogue include all of those detected - candidates and confirmed planets - while Kepler was aimed at the constellation Cygnus, and stared down the length of the Orion Spur, the small arm of the Milky Way Galaxy where Earth's solar system resides.
Kepler performs its mission by gathering extremely stable observations of distant stars, and watches for when the light from those stars dims, due to a solid object (most likely a planet) passing between the telescope and that star. This dimming is known as a "transit".
The first portion of the mission, which lasted roughly four years, ended when the telescope lost two of the reaction wheels that kept its instrumentation stabilized for these careful measurements.
Kepler's latest mission, K2, now observes several locations around the plane of our solar system, as the telescope uses light pressure from the Sun to stabilize its observations. Scientists with the mission expect that Kepler's K2 mission will continue until sometime in 2018.