How the Small Magellanic Cloud Survived its encounter with the Milky Way

This artist`s concept shows the Large Magellanic Cloud, or LMC, in the foreground as it passes through the gaseous halo of the much more massive Milky Way galaxy. The encounter has blown away most of the spherical halo of gas that surrounds the LMC, as illustrated by the trailing gas stream reminiscent of a comet`s tail. The team surveyed the halo by using the background light of 28 quasars, an exceptionally bright type of active galactic nucleus that shines across the universe like a lighthouse beacon. The lines represent the Hubble Space Telescope`s view from its orbit around Earth to the distant quasars through the LMC`s gas. Credit: NASA, ESA, Ralf Crawford (STScI)

doi.org/10.48550/arXiv.24
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#Pequena Nuvem 

NASA`s Hubble Space Telescope has captured a fascinating story of survival in space.

One of the Milky Way`s closest neighboring galaxies, called the Small Magellanic Cloud (LMC), had a dangerous encounter with the massive halo of gas that surrounds our galaxy.

Despite losing most of its halo of gas, the galaxy managed to come out the other side in one piece and continues to form new stars!

What Happened to the LMC”

The LMC is a dwarf galaxy that appears enormous in the southern sky, covering an area 20 times larger than the full Moon.

Astronomers have discovered that the LMC is not orbiting the Milky Way in a stable manner, but is simply passing through it.

During this passage, the galaxy lost much of its halo of gas, something that was first observed thanks to Hubble.

O conceito deste artista mostra um close-up da Nuvem Magalhânica Grande (LMC), uma galáxia anã que é uma das vizinhas mais próximas da galáxia da Via Láctea.Os cientistas acham que a CML acaba de concluir sua maior aproximação com a muito mais massiva Via Láctea. Esse encontro levou embora a maior parte do gás esférico que circunda a CML.O arco roxo brilhante à esquerda representa a borda principal do halo da LMC, que está sendo comprimido enquanto o halo da Milky Way empurra para trás contra a LMC que está chegando.A pressão está destruindo grande parte do chalé da LMC e soprando-o para trás em uma cauda de gás que flui.A galáxia-anã está em um caixão dentro de seu halo remanescente. Uma imagem científica real da LMC é combinada com uma renderização artística do halo da galáxia.

Measuring the Gas Halo

The LMC`s gas halo, now very small, is only about 50,000 light-years across, which is 10 times smaller than the halos of other galaxies of similar mass.

This small size shows the impact of the encounter with the Milky Way.

Even so, the LMC still holds enough gas to form new stars, something smaller galaxies would not be able to do.

The Milky Way Impact:

This gas loss event was caused by a phenomenon called “pressure drag stripping.” Think of the Milky Way as a giant hair dryer, blowing and pushing the gas away from the LMC as it approaches.

This pressure caused most of the gas to be stripped away from the LMC, but it still managed to hold on to a small amount due to its high mass.

If it were a less massive galaxy, it would only be left with old stars with no gas left to form new ones.

This artist`s concept illustrates the Large Magellanic Cloud`s (LMC”s) encounter with the Milky Way galaxy`s gaseous halo. In the top panel, at the middle of the right side, the LMC begins crashing through our galaxy`s much more massive halo. The bright purple bow shock represents the leading edge of the LMC`s halo, which is being compressed as the Milky Way`s halo pushes back against the incoming LMC. In the middle panel, part of the halo is being stripped and blown back into a streaming tail of gas that eventually will rain into the Milky Way. The bottom panel shows the progression of this interaction, as the LMC`s comet-like tail becomes more defined. A compact LMC halo remains. Because the LMC is just past its closest approach to the Milky Way and is moving outward into deep space again, scientists do not expect the residual halo will be lost. Credit: NASA, ESA, Ralf Crawford (STScI)

Why Does This Matter”

Studying this interaction is like having a hands-on lesson on how galaxies interact and how such events were common in the early universe, when galaxies were closer together.

What`s more, Hubble was able to make these observations using ultraviolet light, something that is only possible outside of Earth, where our atmosphere does not block this type of light.

The work continues: scientists want to investigate more parts of the LMC halo, especially where it meets the Milky Way`s halo, like two balloons pressed together.

This research is an example of how Hubble continues to help us learn more about the universe, even after so many years in operation!

Published in 11/18/2024 09h46

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