Way ahead of cosmic collision, Andromeda galaxy's 'halo' is nudging the Milky Way
New Delhi | Jagran Trending Desk: NASA’s Hubble Space Telescope has mapped out a massive halo around Andromeda galaxy that is bumping up against that of our Milky Way much in advance of the cosmic collision. The nearly invisible halo of diffused plasma, observed by a team of researchers, extends 1.3 million light-years from the galaxy -- about halfway to our Milky Way -- and as far as 2 million light-years in some directions.
Andromeda and Milky Way are on a collision course that will cause them to merge four billion years from now into one giant elliptical galaxy. The new landmark study, published in the Astrophysical journal, has suggested that Andromeda’s halo is already beginning to press up against that of out own galaxy.
“Understanding the huge halos of gas surrounding galaxies is immensely important,” NASA quoted co-investigator Samantha Berek of Yale University, as saying. “This reservoir of gas contains fuel for future star formation within the galaxy, as well as outflows from events such as supernovae. It’s full of clues regarding the past and future evolution of the galaxy, and we’re finally able to study it in great detail in our closest galactic neighbor.”
The researchers found that the halo has a layered structure, with two main nested and distinct shells of gas.
“We find the inner shell that extends to about a half million light-years is far more complex and dynamic,” explained study leader Nicolas Lehner of the University of Notre Dame. “The outer shell is smoother and hotter. This difference is a likely result from the impact of supernova activity in the galaxy’s disk more directly affecting the inner halo.”
The Andromeda galaxy, also known as M31, is a barred spiral galaxy approximately 2.5 million light-years from the Earth. With an apparent magnitude of 3.4, the galaxy is among the brightest of the Messier objects, making it visible from Earth on moonless nights.
Posted By: Lakshay Raja