Hubble Catches Stars On The Move

Hubble Catches Stars On The Move

The core of the star cluster in NGC 3603 is shown in great detail in an image from the Wide Field Planetary Camera 2 (WFPC2) camera on the NASA/ESA Hubble Space Telescope.

The image is a colour composite of observations in the WFPC2 filters F555W (blue), F675W (green) and F814W (red). This view shows the second of two images taken ten years apart that were used to detect the motions of individual stars within the cluster for the first time.

The field of view is about 20 arcseconds across. Credit: NASA, ESA and Wolfgang Brandner (MPIA), Boyke Rochau (MPIA) and Andrea Stolte (University of Cologne)

By exploiting the exquisite image quality of the NASA/ESA Hubble Space Telescope and comparing two observations made ten years apart astronomers have, for the first time, managed to measure the tiny motions of several hundred young stars within the central cluster of the star-forming region NGC 3603.

The team was surprised to find that the stars are moving in ways that are at odds with the current understanding of how such clusters evolve. The stars in the cluster have not "settled down" as expected.

With a mass of more than 10 000 suns packed into a volume with a diameter of a mere three light-years, the massive young star cluster in the nebula NGC 3603 is one of the most compact stellar clusters in the Milky Way [1] and an ideal place to test theories for their formation.

A team of astronomers from the Max-Planck Institute for Astronomy in Heidelberg and the University of Cologne led by Wolfgang Brandner (MPIA) wanted to track the movement of the cluster's many stars. Such a study could reveal whether the stars were in the process of drifting apart, or about to settle down.