A new planet with the mass of Earth

  • Scientists have discovered a new planet with the mass of Earth, orbiting its star at the same distance that we orbit our sun.
  • The planet is likely far too cold to be habitable for life as we know it, however, because its star is so faint.
  • But the discovery adds to scientists’ understanding of the types of planetary systems that exist beyond our own.
  • This ‘iceball’ planet is the lowest-mass planet ever found through microlensing.
  • The newly discovered planet, called OGLE-2016-BLG-1195Lb, aids scientists in their quest to figure out the distribution of planets in our galaxy.
  • An open question is whether there is a difference in the frequency of planets in the Milky Way’s central bulge compared to its disk, the pancake-like region surrounding the bulge.
  • OGLE-2016-BLG-1195Lb is located in the disk, as are two planets previously detected through microlensing by NASA’s Spitzer Space Telescope.
  • For the new study, researchers were alerted to the initial microlensing event by the ground-based Optical Gravitational Lensing Experiment (OGLE) survey, managed by the University of Warsaw in Poland.
  • KMTNet consists of three wide-field telescopes: one in Chile, one in Australia, and one in South Africa.
  • Although OGLE-2016-BLG-1195Lb is about the same mass as Earth, and the same distance from its host star as our planet is from our sun, the similarities may end there.
  • OGLE-2016-BLG-1195Lb is nearly 13,000 light-years away and orbits a star so small, scientists aren’t sure if it’s a star at all.
  • Alternatively, it could be a brown dwarf or ultra-cool dwarf star much like TRAPPIST-1, which Spitzer and ground-based telescopes recently revealed to host seven Earth-size planet
  • Ground-based telescopes available today are not able to find smaller planets than this one using the microlensing method.
  • A highly sensitive space telescope would be needed to spot smaller bodies in microlensing events.
  • NASA’s upcoming Wide Field Infrared Survey Telescope (WFIRST), planned for launch in the mid-2020s, will have this capability.

    What is Microlensing?

  • Microlensing is a technique that encourages the discovery of distant objects by using background stars as flashlights.
  • When a star crosses accurately in front of a bright star in the background, the gravity of the foreground star focuses the light of the background star, making it appear brighter.
  • A planet orbiting the foreground object may lead to an additional blip in the star’s brightness. In this case, the blip only lasted a few hours.
  • This technique has discovered the most distant known exoplanets from Earth, and can detect low-mass planets that are substantially farther from their stars than Earth is from our sun.

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