Light-bending technique helps scientists find planets orbiting two suns
- by Minnie Bishop
- in Research
- — Sep 24, 2016
The circumbinary exoplanet is located in the system OGLE-2007-BLG-349 at a distance of roughly 8,000 light-years from Earth. This distance is 14 times the diameter of the moon's orbit around Earth, according to NASA.
The Hubble Space Telescope is a project of worldwide cooperation between NASA and the European Space Agency.
Using the Hubble space telescope, the researchers were then able to detect a background star momentarily aligned with OGLE-2007-BLG-349. It was first spotted in 2007 by ground-based observations from telescopes around the world. When it was first discovered by an global collaboration of researchers in 2007, they detected only one star and a planet, but a detailed analysis also revealed a third body that astronomers could not definitively identify at the time.
Binary stars are common throughout the galaxy, as it has been estimated about half the stars in our sky consist of two stars orbiting each other. This is the first time a binary system plus single exoplanet has been discovered through microlensing. Using Hubble data, the researchers found that the light from the foreground lens system was very faint to be a lone star.
The three objects were discovered in 2007 by an worldwide collaboration of five different groups: Microlensing Observations in Astrophysics (MOA), the Optical Gravitational Lensing Experiment (OGLE), the Microlensing Follow-up Network (MicroFUN), the Probing Lensing Anomalies Network (PLANET), and the Robonet Collaboration.
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"The ground-based observations suggested two possible scenarios for the three-body system: a Saturn-mass planet orbiting a close binary star pair or a Saturn-mass and an Earth-mass planet orbiting a single star", David Bennett of NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the paper's first author, said in a statement. The light magnification can reveal clues to the nature of the foreground star and any associated planets. It orbits the pair of red dwarfs about every seven years.
The desert planet of Tatooine in the Star Wars films is often used to illustrate what rocky planets in these systems might be like with nearly unrelenting sunlight.
Astronomers have in recent years discovered dozens of planets orbiting red dwarfs, with most being so-called "super-Earths". While data from the Kepler Space Telescope is more likely to reveal planets that orbit close to their stars, microlensing allows planets to be found at distances far from their host stars.
The sharp Hubble images allowed scientists to isolate the background source star and the lensing star in the foreground. Hubble's High-Resolution images revealed the system that has the brightness that scientists expected of two closely-orbiting red dwarf stars. But this is the first time astronomers have confirmed such a discovery of a so-called "circumbinary planet" by observing a natural phenomenon called gravitational microlensing, or the bending of light caused by strong gravity around objects in space.
Scientists are now hoping to use Hubble to examine other planets identified by the Kepler space telescope that appear to be orbiting tight binary stars.
