Strange things are afoot in the mysterious heart of the Milky Way. It’s a bustling, star-packed region that also harbors our galaxy’s supermassive black hole, which scientists call Sagittarius A*, or Sgr A*. Amid the millions of young, hot stars zipping around galactic center, astronomers have also spied a tangle of curious filamentlike structures stretching out for light-years. What exactly are the filaments? How did they come to be? And what do they tell us about the Milky Way’s heart? As of yet, these are all open questions.

The person most likely to answer them may be Farhad Yusef-Zadeh, an astrophysicist at Northwestern University, who has been studying the galactic center for decades. In the 1980s he and his colleagues discovered the first known filaments—streaks of superfast particles that stretch vertically through the galactic plane for more than 100 light-years and remain unexplained. And this month Yusef-Zadeh and his colleagues published new research in the Astrophysical Journal Letters showing the Milky Way’s heart unexpectedly hosts a second type of filament, too—so-called horizontal filaments, which are shorter and run parallel, rather than perpendicular, to the galactic plane.

Scientific American spoke with Yusef-Zadeh about these strange filaments and how they may have formed.

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