Four Maunakea Telescopes Chart a Close Encounter Between a Binary Star and the Solar System

An international collaboration led by Gemini and University of Hawai`i astronomers used four Maunakea observatories (CFHT, Keck, IRTF, and UH88) to shed new light on the unusual red dwarf/brown dwarf binary star system WISE J0720AB, which passed through the outer solar system less than 100 millennia ago. A new instrument on the Keck telescope that uses invisible infrared light to correct for the turbulence in Earth’s atmosphere, provided the sharpest images yet of this pair, which comprises a faint red dwarf and a methane-bearing brown dwarf. CFHT was used to carefully chart the motion of this binary in the sky over the last five years, and the combination of data from all four telescopes revealed the precise distance and masses of both objects. The team provides an accurate history of the flyby of WISE J0720AB past our solar system. They found that 80,500 years ago it passed only 68,700 astronomical units from the sun, about four times closer than the closest star today and within the outer parts of our solar system from where some comets originate. Read more about this in the Phys.org article.