Hubble Telescope Reveals Resilient Large Magellanic Cloud After Milky Way Interaction
The NASA/ESA Hubble Space Telescope has unveiled a captivating view of the Large Magellanic Cloud (LMC), showcasing its endurance despite a significant encounter with the Milky Way’s gaseous halo. This interaction stripped much of the LMC’s surrounding gas, but the dwarf galaxy has managed to retain sufficient material to continue star formation, highlighting its robust mass and resilience.
A close neighbor to the Milky Way, the LMC is prominent in the southern sky, appearing 20 times larger than the full Moon. Scientists believe it is not orbiting the Milky Way but instead passing through, having recently completed its closest approach. This event resulted in the loss of a large portion of its gaseous halo.
For the first time, astronomers have successfully measured the LMC’s halo using Hubble’s advanced capabilities. Spanning approximately 50,000 light-years, the halo is unusually compact—about 10 times smaller than halos of similarly massive galaxies. This finding highlights the dramatic impact of the LMC’s interaction with the Milky Way.
“The LMC is a survivor,” said Andrew Fox of AURA/STScI for the European Space Agency, who led the study. “Even with significant gas loss, it retains enough to form new stars. Smaller galaxies wouldn’t survive such interactions—they’d lose all their gas and consist only of aging stars.”
The LMC’s ability to preserve its dense, compact halo stems from its substantial mass—around 10 percent of the Milky Way’s. “The Milky Way’s massive halo truncates the LMC’s gas,” explained Sapna Mishra, the study’s lead author from STScI. “Despite this harsh encounter, the LMC retains a portion of its halo thanks to its considerable mass.”
This gas loss is primarily due to ram-pressure stripping, a process where the dense environment of the Milky Way’s halo forces the LMC’s gas to trail behind like a comet’s tail. “The Milky Way’s push is so strong that most of the LMC’s halo mass has been stripped away, leaving only a compact remnant,” Fox added.
Although much of the gas has been displaced, some may eventually fall back toward the Milky Way. However, the LMC’s core halo is not expected to be entirely lost, as the galaxy is currently moving away into deeper space.
This discovery was made using ultraviolet data from the Mikulski Archive for Space Telescopes at STScI, enabled by Hubble’s capability to observe these wavelengths. By analyzing light from 28 quasars, researchers indirectly observed the LMC’s halo through absorption of background light. Hubble’s Cosmic Origins Spectrograph (COS) allowed precise measurements of gas velocities, revealing new details about the halo.
The LMC serves as an ideal astrophysical laboratory due to its size and proximity, offering valuable insights into galaxy interactions similar to those in the early Universe. “Hubble continues to deliver groundbreaking discoveries, providing a deeper understanding of the Milky Way’s complex history with its neighboring galaxies,” said Professor Carole Mundell, Director of Science at the European Space Agency.
Future studies aim to explore the unexamined front side of the LMC’s halo. “We plan to investigate five regions where the LMC’s halo meets the Milky Way’s, creating a compression effect similar to two balloons pushing against each other,” explained co-author Scott Lucchini from the Center for Astrophysics | Harvard and Smithsonian.
This ongoing research underscores Hubble’s unparalleled contributions to understanding galaxy dynamics and interactions in the cosmos.
