In a new study, scientists show how gas ejected during a galactic fusion may linger at large distances for billions of years, where it will eventually feed it to more massive galaxies to create new stars. The picture shows the Magellan Clouds - a pair of dwarf galaxies that were in the process of merging when they hit the Milky Way. It is expected that their gas will replenish half of the volume consumed by our galaxy
The Magellan Clouds (a pair of dwarf galaxies) were in the agonizing process of merging when they entered our galaxy. It is believed that the duo holds enough gas to replenish half of the Milky Way spent on star formation.
Dwarf galaxies with millions of stars, are eclipsed by larger ones, like the Milky Way, where they live in hundreds and thousands of times more objects. But with a lack of brightness, dwarf galaxies manage to stock up on a huge amount of stellar fuel. It is believed that the hydrogen gas circulating through the Large and Small Magellanic Clouds and other dwarf galaxies plays a key role in the birth of new stars and other small galaxies.
To explore the stellar potential in pairs of dwarf galaxies, scientists decided to consider a remote pair of NGC 4490 and NGC 4485, living at a distance of 23 million light years. NGC 4490 is several times larger than the satellite, but the isolated location allowed us to simulate a possible merger with NGC 4485 without interfering with the gravitational pull of the Milky Way. In simulations it was observed how a large galaxy separates gas from a smaller neighbor. As it merged, the gas tail of a smaller galaxy stretched farther and farther away, which confirmed the assumption with the Magellan Clouds.
It turned out that after the collision and merging of specific galaxies, the gas trail continues to expand. After 5 billion years, the gas tails of the pair will extend to a distance of 1 million light years, which is almost twice its current length. When the data were compared with real observations of NGC 4490/4485 in a telescope, the results coincided, which means the model was accurate.
The results are also consistent with the fact that astronomers know about gas utilization in space. As the gas clouds expand, the gas weakens, which facilitates the movement of most of the galaxy. Modeling suggests that the dispersion process helped the Milky Way to effectively separate gas from the Small Magellanic Cloud and it is this type of gas transfer that can be common in other parts of the Universe.
In addition, scientists suggest that reducing the gas density at the edges of the colliding dwarf galaxies makes it difficult to form new stars. This is consistent with the observations. It is planned to continue the study of other merging dwarf pairs to clarify the model.