NASA's Hubble Space Telescope has captured new insights into the Large Magellanic Cloud (LMC), a dwarf galaxy that is one of the Milky Way's closest neighbors. The LMC appears prominently in the southern night sky, measuring 20 times the diameter of the full Moon.
Researchers suggest that the LMC is not in orbit around the Milky Way but is passing by, having recently completed its closest approach. This encounter has resulted in the loss of much of the LMC's gaseous halo.
In a study to be published in The Astrophysical Journal Letters, astronomers measured the LMC’s halo for the first time, discovering it spans approximately 50,000 light-years—significantly smaller than halos of other galaxies with similar mass.
Andrew Fox, principal investigator from AURA/STScI, remarked, “The LMC is a survivor. Even though it's lost a lot of its gas, it has enough left to keep forming new stars.” The LMC retains a compact halo of gas, attributed to its relatively high mass, which is about 10 percent that of the Milky Way.
STScI's Sapna Mishra explained that the Milky Way's massive halo is truncating the LMC’s gas. Despite this, the LMC still retains some of its halo due to its mass. Most of the gas loss is due to ram-pressure stripping, a phenomenon where the Milky Way's dense environment pushes back against the LMC, creating a trailing wake of gas.
Fox likened the Milky Way to a “giant hairdryer,” blowing gas off the LMC as it approaches. As the LMC moves away from its closest approach, scientists believe it will retain some of its halo, despite the loss of much of it during this interaction.