Milky Way’s Closest Neighbor May Be Tearing Apart – ryan

Scientists at Nagoya University in Japan shared new insights into the motion of massive stars in a nearby galaxy that could completely transform our understanding of galaxy evolution and interactions.

Led by Satoya Nakano and Kengo Tachihara, the team has discovered that the Small Magellanic Cloud (SMC), a dwarf galaxy neighboring the Milky Way, may be getting torn apart by the gravitation pull of the Large Magellanic Cloud (LMC), the SMC’s larger companion, bound to it by gravity.

“When we first got this result, we suspected that there might be an error in our method of analysis. However, upon closer examination, the results are indisputable, and we were surprised,” Tachihara said in a press release.

As one of the closest galaxies to the Milky Way, about 210,000 light years away according to NASA, the SMC allowed the research team to identify and track roughly 7,000 massive stars within it.

These stars are more than eight times the mass of our sun and only survive a few million years before exploding as supernovae. Their presence indicates regions rich in hydrogen gas, a crucial component of star formation.

The results of the Nagoya University study, published in The Astrophysical Journal Supplement Seriesshow that the stars inside the SMC move in opposite directions on either side of the galaxy, as though they are being pulled apart.

Tachihara said: “Some of these stars are approaching the LMC, while others are moving away from it, suggesting the gravitational influence of the larger galaxy. This unexpected movement supports the hypothesis that the SMC is being disrupted by the LMC, leading to its gradual destruction.”

The study has also led to another major discovery, the absence of rotational movement among massive stars, which could put a question mark on previous knowledge of the galaxy.

As it happens in the Milky Way, young massive stars typically move together with the interstellar gas from which they were born, because they have not yet had time to decouple from its motion. However, the stars in the SMC do not follow a rotational pattern, indicating that the interstellar gas itself is also not rotating.

“If the SMC is indeed not rotating, previous estimates of its mass and its interaction history with the Milky Way and LMC might need to be revised. This could potentially change our understanding of the history of the three-body interaction between the two Magellanic Clouds and the Milky Way,” Nakano said in a press release.

Because of the SMC’s similarities to primordial galaxies, particularly its low metallicity and weak gravitational potential, this study can also help scientists understand how galaxies interacted with each other in the early universe, and how they changed over time forming the universe we see today.

“We are unable to get a ‘bird’s-eye view’ of the galaxy in which we live,” Tachihara added. “As a result, the SMC and the LMC are the only galaxies in which we can observe the details of stellar motion. This research is important because it allows us to study the process of star formation in connection with the motion of stars throughout the galaxy.”

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