NASA’s Hubble Space Telescope has discovered that the huge gas halo around the Andromeda galaxy is six times larger and 1.000 times more massive than it was previously assumed. Moreover it extends almost a million light-years away from its host galaxy and halfway into the Milky Way galaxy.
The Andromeda galaxy also known as Messier 31 is the largest galaxy in the local group of galaxies which also includes our Milky Way galaxy and other 45 galaxies. Lying 2.5 million light-years away from the Milky Way galaxy Andromeda has one trillion stars, which is two times the number of stars contained in the Milky Way. In addition it is almost 25% brighter than our galaxy.
The lead author of the study, Nicolas Lehner from the University of Notre Dame, explained:
“Halos are the gaseous atmospheres of galaxies. The properties of these gaseous halos control the rate at which stars form in galaxies according to models of galaxy formation.”
The huge halo of gas which surrounds the Andromeda galaxy is very dark and almost invisible. Its discovery could help scientists find out more about the structure and evolution of majestic giant spiral galaxies which is one of the most often met type of galaxy in the universe. Researchers estimate that the halo contains half the mass of the stars inside the Andromeda Galaxy. In addition if it could be observed with the naked eye the halo in the form of a hot and diffuse gas would have 100 times the diameter of the full moon as observed from Earth.
The researchers examined bright background objects in order to measure the dark gas in the halo and analyzed light changes. They used quasars, very distant and bright cores of active galaxies which are powered by black holes. 18 quasars were used in order to observe how material is distributed behind the visible disk of the galaxy.
Christopher Howk, co-author of the study, explained that while the light from the quasars heads towards Hubble the gas in the halo absorbs some of the light and makes it look a bit darker. By analyzing the dip in brightness scientists were able to determine how much gas there is between the quasar and the Earth.
Scientists cannot yet determine whether a similar halp exists around our galaxy too. But if the Milky Way also has a huge halo it may already be touching with Andromeda’s halo. Hubble indicates that in four billion years from now on the two galaxies could merge and form a huge elliptical galaxy.
Image Source: Viral Portal