The Small Magellanic Cloud is one of the galaxies close to the Milky Way known to scientists. But the latest research has shown that there is a secret hidden inside it, which is that it consists of two galaxies, one of which lies behind the other.
In order for scientists to make this exciting discovery, a team led by Claire Murray, an astronomer at the Space Telescope Science Institute in Maryland, studied the movement of gas clouds and young stars within the Small Magellanic Cloud, which is about 199,000 light-years from Earth.
The team discovered that the small galaxy, which is about 18,900 light-years across, contains two distinct star nurseries separated by thousands of light-years.
The Small Magellanic Cloud and the Large Magellanic Cloud are dwarf galaxies, and are strongly connected by gravitational forces to the Milky Way. The two galaxies are gradually attracted towards our galaxy with the aim of colliding and merging in the distant future.
While the Large Magellanic Cloud has a disc-shaped shape similar to the Milky Way, the Small Magellanic Cloud is more organized, with a mass equivalent to a third of the mass of the largest dwarf galaxy, which is approximately 7 billion times the mass of the Sun.
The Small Magellanic Cloud was previously thought to be composed of several components, but it was blurred by the presence of interstellar clouds of gas and dust, making it difficult to distinguish those components.
For the new detection of the Small Magellanic Cloud, Murray and her team expanded the observations by using the Australian Pathfinder Square Kilometer Array, consisting of 36 antenna dishes, to analyze radio waves emitted by hydrogen gas in the dwarf galaxy.
The team followed up these observations using the European Space Agency’s Gaia spacecraft, which is currently creating a 3D map of the stars in the Milky Way, to track the speed and direction of younger stars in the Small Magellanic Cloud, which is more than 10 million years old.
By hypothesizing that these young stars move in sync with the large clouds of gas they generated, distinct peaks of gas and dust that contribute to star formation have been discovered.
The two clouds contain different amounts of heavy elements, meaning elements that weigh more than hydrogen and helium. It appears that one of the clouds is farther from the Earth than the other, but the exact separation between them has not yet been determined.
One challenge scientists hope to solve is whether these two objects were held together by gravitational forces, or if one formed from gaseous material that was separated from the other by gravitational effects with the Large Magellanic Cloud.
sources:
– Astrophysical Journal
– National Institute of Space and Astronomy.
