In a recent observation, NASA’s Hubble Space Telescope has documented a close interaction between the Milky Way and one of its nearest galactic neighbours, the Large Magellanic Cloud (LMC). This recent analysis of the LMC, led by Andrew Fox of the European Space Agency’s Space Telescope Science Institute (STScI) in Baltimore, reveals the effects of its near-collision with the Milky Way’s massive halo, including a significant reduction of the LMC’s own halo of gas.
The LMC’s Halo: A Surprising Measurement
For the first time, Hubble data allowed researchers to measure the extent of the LMC’s halo, which is now estimated at 50,000 light-years across, considerably smaller than other galaxies of similar mass. This contraction of the halo, explained Fox, points to the effects of the LMC’s encounter with the Milky Way, which stripped away a considerable portion of its outer gas layer. Despite these losses, the LMC still contains sufficient gas to form new stars, adding resilience to the otherwise diminished dwarf galaxy.
Ram-Pressure Stripping: The Force at Play
A process known as ram-pressure stripping is responsible for much of the LMC’s halo loss. As the LMC approached the Milky Way, the larger galaxy’s gravitational influence exerted a “wind” effect, pushing back the LMC’s gas into a tail-like stream that now trails the galaxy. Sapna Mishra, lead author on the research paper, likened this force to a powerful “hairdryer,” stripping away the LMC’s gas. This gas, however, is not expected to be completely lost, as the galaxy begins to move away from the Milky Way after its closest pass.
Future Research and Cosmic Implications
As the team moves forward, plans are in place to study the leading edge of the LMC’s halo, which remains largely unexplored. Scott Lucchini of the Centre for Astrophysics | Harvard & Smithsonian remarked that this research will focus on the collision points between the two halos, providing insight into the nature of galactic interactions in the universe’s early days.