September 24, 2021

I, Science

The science magazine of Imperial College

A map of the Milky Ways’s entire central bulge, displaying 84 million stars, has been created. The central bulge formed early on in our galaxy’s life, and so understanding what goes on in there could help astronomers learn more about how galaxies get to be the way they are.

The bulge contains huge numbers of densely packed stars and clouds of dust. These make the area difficult to effectively probe with visible light. But the ESO’s VISTA telescope uses a powerful infra-red detector which circumnavigates this problem. The telescope has now been used to produce a map of the region that’s 10 times more detailed than ever seen before.

The full-resolution image contains over nine billion pixels, making it one of the biggest astronomical images ever produced. If rendered in the resolution of a typical book, it would be nine metres tall.

A team led by Roberto Saito, of the Pontifical Catholic University, Chile, have used the observations to plot a colour-brightness graph for all the stars. This whopping data set will enable astronomers to calculate the physical properties of each individual star. It’s common for scientists to use these characteristics to deduce the age, mass and temperature of stars, and with each one occupying a unique position on the graph, this becomes a more manageable task.

The star census data is freely available online, so it will be possible for the wider scientific community to have a hand in drawing interpretations of this new information goldmine.

REFERENCE: R. Saito et al., Astronomy and Astrophysics, DOI: 10.1051/0004-6361/20121944)

IMAGE: ESO/VVV Consortium and Ignacio Toledo