Huge exoplanet found in the center of the Milky Way

Object's mass is just at boundary between most massive planets and brown dwarfs.
By Laurel Kornfeld | Nov 10, 2017
Scientists using gravitational microlensing with NASA's Spitzer Space Telescope discovered a massive exoplanet orbiting a star slightly smaller than the Sun in the Milky Way's central galactic bulge.

At 13.4 times the mass of Jupiter, the planet, known as OGLE-2016-BLG-1190Lb, may actually be a brown dwarf, the lowest mass object in the stellar category. Brown dwarfs fuse deuterium, an isotope of hydrogen, and form from a collapsing cloud of gas and dust the way stars do.

Discovered in June 2016, the planet is the first ever found in the galactic bulge and is located approximately 22,000 light years from Earth.

Scientists use microlensing to search for planets in regions such as the galactic bulge, where they are difficult to find using other methods.

When a foreground object, such as a star, moves in front of a more distant object, the former bends the light of the latter, magnifying it.

Planets can be found with this method because it does not require the light of their parent stars.

The Optical Gravitational Lensing Experiment (OGLE), based at the University of Warsaw in Poland, searches for both exoplanets and dark matter via microlensing using the 1.3-meter Warsaw telescope at the Las Campanas Observatory in Chile.

Following the planet's discovery, an international team of scientists led by Yoon-Hyun Ryu of the Korea Astronomy and Space Science Institute in Daejon, South Korea, spent several days observing it using Spitzer.

At approximately two astronomical units (AU, with one AU equal to the average Earth-Sun distance or 93 million miles) from its parent star, the giant planet takes about three Earth years to complete a single orbit.

Its parent star is a G dwarf with 0.89 solar masses.

"We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object," the science team reported in a paper published in the journal Earth and Planetary Astrophysics.

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