Hubble reveals what happened when a galaxy came close to Milky Way

New Delhi,UPDATED: Nov 15, 2024 12:27 IST

In a groundbreaking discovery, NASA's Hubble Space Telescope has unveiled the remarkable survival story of the Large Magellanic Cloud (LMC), one of the Milky Way's closest galactic neighbours.

This dwarf galaxy, visible in the southern night sky, has endured a close encounter with our galaxy, emerging battered but resilient.

Researchers have long theorised that the LMC is not in orbit around the Milky Way but is merely passing by.

Recent observations using Hubble have allowed astronomers to measure the size of the LMC's halo for the first time.

The findings, to be published in The Astrophysical Journal Letters, reveal a surprisingly compact halo, measuring only about 50,000 light-years across – approximately 10 times smaller than halos of similarly sized galaxies.

Andrew Fox, the principal investigator from AURA/STScI, describes the LMC as a "survivor." Despite losing a significant amount of gas, the galaxy retains enough to continue forming new stars, a feat that smaller galaxies would not have accomplished.

The LMC's close passage to the Milky Way has resulted in a phenomenon called ram-pressure stripping.

As the LMC moves through the dense environment of our galaxy, much of its halo is blown away, creating a comet-like tail of gas. Sapna Mishra, the lead author of the study, explains that even with this catastrophic interaction, the LMC's substantial mass allows it to retain about 10% of its halo.

This research was made possible by Hubble's unique ability to detect ultraviolet light, which is blocked by Earth's atmosphere. The team analysed observations from the Mikulski Archive for Space Telescopes, using the light from 28 bright quasars to indirectly observe the LMC's halo gas.

As the LMC moves away from its closest approach to the Milky Way, scientists expect it to retain some of its halo. The research team plans to further investigate the collision zone between the LMC's and Milky Way's halos, promising more insights into this cosmic survival story.