Astronomers have used the light-warping effects of gravity to spot a massive object OGLE-2016-BLG-1190Lb using NASA’s infrared Spitzer Space Telescope, 13 times the mass of Jupiter and orbits a star about 22,000 light years away. This new discovery of an absolutely massive planet residing in our galaxy’s “bulge” (image above) has scientists struggling to explain if it’s a huge unknown planet or a failed star.
The object’s unusual size suggests it may be a brown dwarf, sometimes called “failed stars,” objects so massive that they generate heat, though only in the range of about 300 to 400 degrees Fahrenheit, but not massive enough to sustain the nuclear fusion that powers main sequence stars.
The line between true planets and brown dwarfs is somewhere between 13 and 14 Jupiter masses, and with a mass of approximately 13.4 Jupiter masses. OGLE exists on the edge of what’s known as the brown dwarf desert – a range of orbits described as a zone devoid of failed stars.
Astronomers have noticed there’s a distinct lack of brown dwarfs within 5 AU of other stars. OGLE has an orbit approximately 5 AU from its companion star that takes about three years to complete. If it is a planet, it’s grown to mammoth proportions.
“Since the existence of the brown dwarf desert is the signature of different formation mechanisms for stars and planets, the extremely close proximity of OGLE-2016-BLG-1190Lb to this desert raises the question of whether it is truly a ‘planet’ (by formation mechanism) and therefore reacts back upon its role tracing the galactic distribution of planets,” the researchers observed.
GLE-2016-BLG-1190Lb, is the first Spitzer microlensing exoworld residing in the galactic bulge. The finding was presented October 27 in a paper published on arXiv.org.
Microlensing is very useful technique for detecting alien worlds in the inner galactic disk and bulge, where it is difficult to search for planets with other methods, observed Phys.org. It facilitates the discovery of distant objects by using background stars as flashlights. If a star moves in front of an another star, the light from the distant star is bent by the gravitational pull of the nearer star and the more distant star is magnified. Microlensing does not rely on the light from the host stars; thus, it can detect planets, even when the host stars cannot be detected.
OGLE-2016-BLG-1190 was discovered in June 2016 as a microlensing event by the Optical Gravitational Lensing Experiment (OGLE) collaboration. OGLE is a Polish astronomical project based at the University of Warsaw, searching for dark matter and extrasolar planets. It utilizes the 1.3 meter Warsaw telescope mounted at the Las Campanas observatory in Chile.
Spitzer observed this microlensing event a few days after its discovery. An international team of researchers led by Yoon-Hyun Ryu of the Korea Astronomy and Space Science Institute in Daejon, South Korea, reports that these Spitzer observations detected a new, massive planet orbiting a dwarf star.
“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 astronomers wrote in the paper.
The Daily Galaxy via arXiv.org and Phys.org