Credit: NASA, ESA, and E. Wheatley (STScI)

This illustration shows the location of the 43 quasars scientists used to probe Andromeda’s gaseous halo. These quasars—the very distant, brilliant cores of active galaxies powered by black holes—are scattered far behind the halo, allowing scientists to probe multiple regions. Looking through the immense halo at the quasars’ light, the team observed how this light is absorbed by the halo and how that absorption changes in different regions. By tracing the absorption of light coming from the background quasars, scientists are able to probe the halo’s material.

Provider: Space Telescope Science Institute

Image Source: https://hubblesite.org/contents/news-releases/2020/news-2020-46

Curator: STScI, Baltimore, MD, USA

Image Use Policy: http://hubblesite.org/copyright/