Star or not? The common prediction is that the Milky Way will collide with its neighboring galaxy Andromeda in about four billion years. But a new model now describes a different scenario. For example, two other galaxies – the Large Magellanic Cloud and the spiral galaxy M33 – influence the galactic orbits and thus the probability of a collision. The Milky Way therefore has about a 50% chance of escaping the galactic collision, according to astronomers.
THE Milky Way and their neighbors have a history of collisions, near-collisions, and mergers. Our home galaxy absorbed several neighboring dwarf galaxies, while the Andromeda Galaxy took over one about two billion years ago. little brother swallowed by the Milky Way. The future also looks eventful: in about 2.4 billion years, the Milky Way will probably be joined by the Large Magellanic Cloud (LMC). collide.
Two spiral galaxies on a collision course
But the two largest galaxies in the Local Group are also on a collision course: the Milky Way and the Andromeda Galaxy are heading directly toward each other. The two galaxies of equal size are currently only 2.5 million light-years apart. touch each other Their halos extend far into space. According to current assumptions, the two spiral galaxies will merge in four to five billion years at the latest.
“This scenario has become the dominant school of thought,” explain Till Sawala of the University of Helsinki and his colleagues. “As a result of their collision, the two large spiral galaxies will merge to form a new elliptical galaxy. However, the Milky Way and Andromeda are not alone: in the Local Group, there are other nearby galaxies that influence the future.” orbits of the two stellar spirals, including the
Large Magellanic Cloud and the triangular galaxy M33.
In addition, some masses of galaxies in our local group have recently been re-evaluated. These new values also influence their orbits and gravitational effects.
Four players in galaxy billiards
Sawala and his team therefore took a closer look at how certain a collision between the Milky Way and Andromeda still is, given these factors. To do this, they used a computer model of the Local Group, which they fed with the latest data on the four galaxies. They then tracked how the future path of the Milky Way and Andromeda changes when exposed to the influence of the other two galactic “actors.”
The result: If the Milky Way and the Andromeda Galaxy were alone in space, their current trajectory would result in a collision in about half of the possible cases. “If we include the triangular galaxy M33, this increases the probability of a merger by two-thirds,” the astronomers report. There is an 86% probability that this galaxy will merge with the Andromeda Galaxy before the “big collision,” giving it an extra push toward the Milky Way.
The odds are 50:50
But the picture changes if we add the fourth “actor”, the Large Magellanic Cloud: “This has the opposite effect: if only the Milky Way, Andromeda and LMC are involved, the risk of collision is only one third if we take all four into account, the probability is just over 50 percent,” report Sawala and his team. The reason is: the Large Magellanic Cloud is moving perpendicular to the collision path of the two spiral galaxies. Therefore, if it collides with the Milky Way, it will probably deflect it.
This means that the question of whether there will actually be a “big collision” between the Milky Way and the Andromeda Galaxy is far from certain. “Even if we use the most recent and precise observational data, the future development of the Local Group is rather uncertain,” the astronomers write. The scenario of a widespread collision is therefore no more likely than the absence of such a collision. (arXiv preprint, 2024; is what i: 10.48550/arXiv.2408.00064)
Source: arXiv
August 14, 2024 – Nadja Podbregar