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Milky Way disc much bigger than thought: Study

Press Trust of India  |  London 

It would take us 200,000 years to cross the disc of our if we could travel at the speed of light, say scientists who found that the disc of the is bigger than thought.

Spiral galaxies such as the have discs which are really thin, in which the major fraction of their stars are found. These discs are limited in size, so that beyond certain radius there are very few stars left.

In our we were not aware that there are stars in the disc at distances from the centre more than twice that of the Sun. This means that our own star was apparently orbiting at about half the galactic radius.

However, now we know that there are stars quite a bit further out, at more than three times this distance, and it is probable that some stars are at more than four times the distance of the Sun from the

"The disc of our is huge, around 200 thousand light years in diameter," said Martin Lopez-Corredoira, a at the (IAC) in

In broad terms we can think of galaxies like the as being composed of a rotating disc, which includes spiral arms, and a halo, spherical in shape, which surrounds it.

This piece of research has compared the abundances of metals (heavy elements) in the stars of the Galactic plane with those of the halo, to find that there is a mixture of disc and halo stars out to the large distances indicated.

The researchers came to these conclusions after make a statistical analysis of survey date from and LAMOST, two projects which obtain spectra of stars to extract information about their velocities and their

"Using the metallicities of the stars in the catalogues from the high quality spectral atlases of and LAMOST, and with the distances at which the objects are situated, we have shown that there is an appreciable fraction of stars with higher metallicity, characteristic of disc stars, further out than the previously assumed limit on the radius of the Galaxy disc" said Carlos Allende, a at the

"We have not used models, which sometimes give us only the answers for which they were designed, but we have employed only the statistics of a large number of objects. The results are therefore free from a priori assumptions, apart from a few basic and well established ones," said Francisco Garzon, an

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)

First Published: Sun, June 10 2018. 12:05 IST