Researchers have discovered a huge halo of gas which surrounds Andromeda, our nearest neighboring galaxy. The halo which stretches million light-years outside the galaxy could help scientists find out more about the spirals in the universe. The research was published in the Astrophysical Journal.
The investigators involved in the study claim that the diffuse gas in the halo weighs half the mass of the stars in the Andromeda Galaxy. The galaxy also known as Messier 31 or the punchier M31 has one trillion stars and it is believed to be brighter and bigger than our Milky Way galaxy.
Using NASA’s Hubble Space Telescope scientists estimate that the halo is 1.000 times more massive and six times larger than it was previously believed. The lead author of the study, Nicolas Lehner from the University of Notre Dame explained that halos represent the gaseous atmosphere of galaxies. The properties of these halos control the rate of star formation in galaxies in accordance with models of galaxy formation.
Researchers also estimate that the halo could be roughly 100 times the diameter of the moon. The halo is very dark, almost invisible. In order to get around this issue the scientists analyzed the bright background objects whose light was influenced by the gas which intervened in the halo. Such bright objects are quasars: dazzling bursts of energy coming from matter which falls into supermassive black holes and is spewed back out.
Some light of the quasar is absorbed by the gas from the halo which makes it appear slightly darker. By doing this researchers were able to measure the changes in brightness and estimate how much gas there is between the quasar and the Earth. It seems that Milky Way could have a halo just like the Andromeda galaxy. This means that in approximately four billion years the two galaxies could collide and generate a he elliptical galaxy. However it is unlikely that Earth’s halo will be found.
Simulations of the galaxies at a large scale indicate that the halo formed along with the rest of the galaxy. The scientists observed that it contains elements which are much heavier than helium and hydrogen. The only way in which could have been produced is through supernovas. Andromeda’s star-filled disk has many supernovas which erupt and blow these heavy elements out into space.
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