The phenomenon of gas rivers flowing into the Bima galaxy. (Photo: Harvard-Smithsonian Center for Astrophysics)
JAKARTA – The phenomenon of gas rivers flowing into the Milky Way galaxy has puzzled astronomers for decades. Later, the answer was solved. This was thanks to the services of the Magellan Baade telescope at the Las Campanas Observatory in Chile.
Based on existing research, a stream of hydrogen gas comes out of the Large Magellanic and Small Magellanic clouds, two small galaxies located on the outskirts of the Milky Way. The contents of this stream, known as the Magellanic Stream, have been a mystery for decades. But now, for the first time, the research team has revealed the existence of stars within these flowing gas clouds. This discovery will not only help understand the evolution of the Magellanic Stream’s home galaxy, but also the distribution of matter in the Milky Way.
Harvard-Smithsonian Center for Astrophysics astronomers discovered the stars using the 6.5-meter Magellan Baade Telescope at the Las Campanas Observatory in Chile. With the help of a detailed map of the Milky Way, created by the European Space Agency’s Gaia space telescope, the researchers focused on 200 stars located in the farthest reaches of our galaxy, in the direction of the Magellanic Stream.
They analyzed the spectrum of light emitted by those stars and found the chemical composition of 13 subjects matched that of the Magellanic Clouds. Measurements also show the 13 stars are 150,000 to 400,000 light years from Earth, about the expected distance from the Magellanic Stream.
The Magellanic Stream, originally discovered in the 1970s, extends across an area of the southern sky equivalent to the size of 300 full moons as seen from Earth. However, even though they are large, special equipment is needed to see them.
Astronomers think the gas that forms these flows is released from the dwarf galaxy by the Milky Way’s gravitational pull. These new observations may reveal more about the nature of this flow and help scientists trying to understand how it interacts with the Milky Way galaxy.
Currently, scientists say, this stream appears to be falling into the Milky Way. “With results like these we hope to gain much greater understanding of the formation of the Magellanic Stream and Magellanic Clouds, as well as their past and future interactions with our galaxy,” said Charlie Conroy, Professor of Astronomy at the Harvard-Smithsonian Center for Astrophysics (CfA ).
Unlike the Magellanic Stream, the Magellanic Clouds have been known to mankind since ancient times because they can be seen with the naked eye. However, astronomers still have many questions about the origin of these two galaxies, which appear to collide with the Milky Way.
Mapping and modeling the Magellanic Stream will help astronomers advance understanding of its source galaxy, which is believed to trace its past trajectory.
Scientists think that hydrogen gas from these gas rivers fell into the Milky Way, creating the right conditions for star formation. By analyzing the data, the researchers also found this flow is about twice as massive as previously thought, meaning the Milky Way must be absorbing more gas than previously calculated.
“The Magellanic Stream is the main source of stellar calories for the Milky Way,” said Ana Bonaca, one of the authors of the study and a former postdoctoral researcher at CfA, who is now a staff scientist at Carnegie Observatories.