Illustration of ASASSN-14li
This artist's illustration shows the region around a supermassive black hole after a star wandered too close and was ripped apart by extreme gravitational forces in a source called ASASSN-14li. Some of the remains of the star are pulled into an X-ray-bright disk where they circle the black hole before passing over the "event horizon," the boundary beyond which nothing, including light, can escape.
(Illustration Credit: NASA/CXC/M.Weiss)

Chandra X-ray & Hubble Optical images of ASASSN-14li
Scientists used Chandra and other telescopes to study this event and determine the spin rate of the black hole, a fundamental property that has been difficult for astronomers to measure.
(Credit: X-ray: NASA/CXC/MIT/D. Pasham et al: Optical: HST/STScI/I. Arcavi)