Science News

NASA’s Hubble Telescope Finds Massive Gaseous Halo Surrounding Andromeda Galaxy

A team of scientists from the University of Notre Dame have discovered a massive halo of gas surrounding the Andromeda Galaxy, our nearest galactic neighbor, with the help of NASA’s Hubble Space Telescope.

According to UND News, the halo stretches around millions of light-years from Andromeda, halfway to the Milky Way. The finding will help astronomers better understand the structure and evolution of majestic spiral galaxies such as the Andromeda and Milky Way.

[quote text_size=”small” author=”– Nicolas Lehner” author_title=”Lead investigator at the University of Notre Dame, Indiana”]

Halos are the gaseous atmospheres of galaxies. The characteristics of these gaseous halos control the rate at which stars form in galaxies. The enormous halo is estimate to contain at least half the mass of stars in the Andromeda Galaxy in form of a hot, dispersed gas.


The Andromeda Galaxy, also known as M31, is the most massive galaxy from a local group of galaxies containing 46 other known galaxies, including the Milky Way. Scientists estimate that the Andromeda Galaxy contains one trillion stars and is located 2.5 million light-years away from it’s near-twin, the Milky Way, as reported by

In order to find the gaseous halo, scientists were examining quasars, extremely luminous star-like objects whose light is affected by the interposing gas in the halo. They shine brightly due to the presence of the gas falling onto gargantuan black holes in their cores.

[quote text_size=”small” author=”– Jay Christopher Howk” author_title=”Associate professor of physics at Notre Dame and co-investigator”]

As the light from quasars travels toward Hubble Space Telescope, the halo’s gas will absorb some of the light, making the quasar appear a little bit darker. By measuring the decline in brightness we were able to determine how much halo gas from Andromeda is between us and the quasars.


According to these findings, scientists predict that if the Milky Way were to possess a halo similar to Andromeda’s, the two galaxies’ halos could fuse before the two massive galaxies collide beginning about 4 billion years from now.

Unrelated to this study, Yale astronomer Pascal Oesch has discovered EGS-zs8-1, galaxy thought to be one the earliest galaxies formed in the history of the cosmos, in images taken by NASA’s Hubble and Spitzer space telescopes.

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