Planet or Star? A New Discovery Fuels Astronomical Questions

 

OGLE-2016-BLG-1190 pic

OGLE-2016-BLG-1190
Image: phys.org

A native of Westbury, NY, Valerie Varnuska enjoys exploring the many natural wonders near her hometown. In addition to walking the nature trails near Westbury, NY, Valerie Varnuska pursues a strong interest in astronomy and viewing the various celestial bodies in the night sky.

A recent discovery is fueling new discussions regarding the classification of astronomical objects. In June 2016, researchers working on the Optical Gravitational Lensing Experiment at the University of Warsaw discovered a celestial body that appears to straddle the line between a planet and a brown dwarf, a lesser variety of star. They discovered the body, labeled OGLE-2016-BLG-1190, using an indirect method of observation capable of detecting signs of the far-off world some 22,000 light years away. Researchers first detected the world due to an astronomical phenomenon known as a gravitational microlensing event, during which its gravitational pull temporarily intensified the light emitted from its parent star.

Using data from the microlensing event, researchers from the Korea Astronomy and Space Science Institute determined that OGLE-2016-BLG-1190 is approximately 13 times the mass of Jupiter, making it 4,000 times denser than Earth. At this size, the world rests on the boundary between a planet and a brown dwarf star. Much like a brown dwarf, the object also appears to emit a small amount of energy by fusing deuterium, an isotope of hydrogen.

The newly discovered celestial object primarily differs from other brown dwarfs in its location relative to its parent star. Brown dwarfs typically do not orbit at a distance closer than five times Earth’s orbital distance from the sun, most likely due to a dearth of gases capable of forming such an object. However, the newly discovered body orbits its star at just twice the distance of Earth, placing it in a region known as the brown dwarf desert. The discovery of this apparent anomaly has fueled further research into the formation of brown dwarf stars. Researchers will have another chance to observe the unique semi-planet in 2019, when its latest three-year orbit causes another microlensing event.

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