A microlensing event has revealed an elusive brown dwarf. Discovery of the new brown dwarf star was made possible by a unique collaboration between NASA’s Spitzer and Swift space telescopes.
Microlensing is a phenomenon whereby an objects in space, often invisible to the eyes of astronomers, are revealed by the magnification caused by the gravitational field of one or more objects situated between the elusive object and the lens of a telescope.
Brown dwarf stars aren’t exactly stars. They’re somewhere between a star and a planet — roughly 80 times the size of Jupiter but not hot enough to generate energy through nuclear fusion.
Brown dwarfs typically orbit a larger star. Interestingly, scientists have found very few brown dwarfs orbiting within three astronomical units of sun-sized stars. An astronomical unit, or AU, is the distance between Earth and the sun.
“We want to understand how brown dwarfs form around stars, and why there is a gap in where they are found relative to their host stars,” Yossi Shvartzvald, a NASA postdoctoral fellow working at NASA’s Jet Propulsion Laboratory, said in a news release.
Researchers were able to ascertain more accurate information about the newly discovered brown dwarf — its size and the distance from its host star — by viewing the microlensing event from more than one angle. The more angles, the better, scientists say.
“In the future, we hope to have more observations of microlensing events from multiple viewing perspectives, allowing us to probe further the characteristics of brown dwarfs and planetary systems,” said JPL scientist Geoffrey Bryden.
Researchers described their discovery of the brown dwarf and analysis of the microlensing data in a new paper, published this week in the Astrophysical Journal.
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