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Hubble unveils half a million stars at Milky Way’s heart

Friday, Apr 1, 2016,11:58 IST By Metrovaartha A A A

Washington | NASA’s Hubble Space Telescope has unveiled a rich tapestry of more than half a million tightly packed stars at the heart of our Milky Way galaxy. The stars are part of the Milky Way’s nuclear star cluster, the most massive and densest star cluster in our galaxy, NASA said.

So packed with stars, it is equivalent to having a million suns crammed into the volume of space between us and our closest stellar neighbour, Alpha Centauri, researchers said. At the very hub of our galaxy, this star cluster surrounds the Milky Way’s central supermassive black hole, which is about 4 million times the mass of our Sun.

Astronomers used Hubble’s infrared vision to pierce through the dust in the disk of our galaxy that obscures the star cluster. In the image obtained by the Hubble telescope, scientists translated the infrared light, which is invisible to human eyes, into colours our eyes can see. In the image, extremely dense clouds of gas and dust are seen in silhouette, appearing dark against the bright background stars.

The clouds are so thick that even Hubble’s infrared capability could not penetrate them. Hubble’s sharp vision allowed astronomers to measure the movements of the stars over four years. Using this information, scientists were able to infer important properties such as the mass and structure of the nuclear star cluster.

The motion of the stars may also offer a glimpse into how the star cluster was formed – whether it was built up over time by globular star clusters that happen to fall into the galaxy’s centre, or from gas spiralling in from the Milky Way’s disk to form stars at the core.

The image, spanning 50 light-years across, is a mosaic stitched from nine separate images taken in 2010 through 2014 with Hubble’s Wide Field Camera 3. The centre of the Milky Way is located 27,000 light-years away. Astronomers estimate that about 10 million stars in this cluster are too faint to be captured in the image.