- 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.