London (Agencies): Astronomers, for the first time have discovered a thick stellar disc consisting older stars in the large spiral galaxy Andromeda Galaxy, nearest to our own Milky Way.

The disc, also known as Messier 31, has been located some 2.5 million light years away in the constellation Andromeda. The scientists believe that the finding of the disc is expected to help them better understand the processes involved in the formation and evolution of such galaxies.

A team of researchers found the disc during a five-year study with the help of the Keck Telescope in Hawaii and analyzed the velocities of individual bright stars within the Andromeda Galaxy, the Daily Mail reported.

They were able to observe a group of stars tracing a thick disc -- distinct from those comprising the galaxy's already-known thin disc -- and assessed how these stars differ
from thin-disc stars in height, width and chemistry.

Approximately 70 per cent of Andromeda's stars are contained in the galaxy's thin stellar disc which surrounds a central bulge of old stars at the core of the galaxy, said the
researchers.

Lead researcher Michelle Collins from the University of Cambridge's Institute of Astronomy said: "From observations of our own Milky Way and other nearby spirals, we know that  these galaxies typically possess two stellar discs, both a 'thin' and a 'thick' disc."

"The classical thin stellar discs that we typically see in Hubble imaging result from the accretion of gas towards the end of a galaxy's formation, whereas thick discs are produced in a much earlier phase of the galaxy's life, making them ideal tracers of the processes involved in galactic evolution," said Collins.

Astronomers will be able to determine the properties of the disc across the galaxy and will search for signatures of the events related to its formation, the researchers said.