The Milky Way’s numerous mysteries are cracked up one by one, and the latest groundbreaking finding could help unveil the unknown features and causes behind certain events and activities of our home galaxy.
Researchers have discovered a halo of plasma around the neighboring galaxy, Andromeda, using the Hubble Space Telescope. They have then mapped the massive halo of gas in the most detailed chart of its kind, showing how the halo – electrically charged gas – around this spiral galaxy extends around 1.3 million light-years towards the Milky Way.
A Halo of Gas
The distance is around half the galaxy’s size and spreads as much as two million light-years in some directions. Oddly enough, the halo is invisible to the naked eye. Still, astrophysicists say that if it was visible, it would be approximately three times the width of the Big Dipper or Plough.
Team member of the research, Samantha Berek at Yale University, explained how the finding might further our understanding of our own universe.
She said: “Understanding the huge halos of gas surrounding galaxies is immensely important. This reservoir of gas contains fuel for future star formation within the galaxy, as well as outflows from events such as supernovae. It’s full of clues regarding the past and future evolution of the galaxy. We’re finally able to study it in great detail in our closest galactic neighbor.”
The team of researchers found that Andromeda’s halo is made of two distinct layers. The ‘inner’ shell has a more intricate structure than the outer shell, which is probably the result of supernovas in the galaxy’s disk. The powerful explosions, which are actually deaths of massive stars, throw heavy elements into space. These elements were also identified in high amounts within the halo.
In order to map more details about the halo, ultraviolet light from 43 distant quasars was analyzed. The team used the Hubble Space Telescope’s Cosmic Origins Spectrograph instrument to understand how this background light was consumed by the halo’s gas in various regions. This unveiled variations in the gas’ structure.
Andromeda is believed to be similar in size and shape to the Milky Way. The discoveries, therefore, could be of great help to understanding our own galactic halo, which is far more difficult to map from our position inside the Milky Way.