What would the Magellanic Clouds have evolved into, were they far from the Milky Way?

July 11, 2018

Optical deep image of NGC 4490 (large) and NGC 4485 (small) obtained with the BBRO2 0.5-meter telescope. Credit: Pearson et al. 2018.

Our close neighboring galaxies, the Magellanic Clouds, are readily visible to the naked eye and have long been known to human civilizations across the southern hemisphere, playing important roles in their mythology and culture. The Large and Small Magellanic Clouds are classified as “dwarf galaxies”, and they have a factor of ~20 and ~200 fewer stars than the Milky Way respectively. The two dwarfs have likely interacted with each other for several billion years, and are only now, for the first time, passing close by our Galaxy.

Several astronomers have modeled their evolution, but due to their close proximity to the Milky Way it has been difficult to disentangle their previous interaction history and ultimate fate.

In a new article, lead by Dr. Sarah Pearson who recently received her PhD from Columbia University, astronomers (including Columbia U. Professors Mary E. Putman and Kathryn V. Johnston) study a pair of dwarf galaxies, NGC 4490 & NGC 4485 (see Figure) which are similar to the Magellanic Clouds, but far from any more massive galaxy. In particular the authors matched computer simulations of the galaxy interaction to data of the pair. The isolated environment of NGC 4490/85 enabled the authors to investigate the single effect of the mutual interaction between two dwarfs. This allows them to ask: what would the Magellanic Clouds have evolved into, had they not been close to the Milky Way?

Interpreting these types of interactions has important implications for understanding galactic growth in the early Universe, where galaxies are thought to build their mass by colliding with other galaxies and by accreting smaller systems. In fact, the Milky Way is still devouring smaller galaxies at present day.

Link to Columbia's press release here>>

Read full popular science article here>>

Read the scientific paper on the arXiv here>>

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