Hubble traces the halo of a galaxy more accurately than ever before: The galaxy’s halo of stars has been found to extend much further from the galaxy’s centre than expected…. This is the most remote portion of an elliptical galaxy ever to have been explored.
Astronomers using the NASA/ESA Hubble Space Telescope have probed the extreme outskirts of the stunning elliptical galaxy Centaurus A. The galaxy’s halo of stars has been found to extend much further from the galaxy’s centre than expected and the stars within this halo seem to be surprisingly rich in heavy elements. This is the most remote portion of an elliptical galaxy ever to have been explored.
There is more to a galaxy than first meets the eye. Extending far beyond the bright glow of a galaxy’s centre, the swirling spiral arms, or the elliptical fuzz, is an extra component: a dim halo of stars sprawling into space.
These expansive haloes are important components of a galaxy. The halo of our own galaxy, the Milky Way, preserves signatures of both its formation and evolution. Yet, we know very little about the haloes of galaxies beyond our own as their faint and spread-out nature makes exploring them more difficult. Astronomers have so far managed to detect very few starry haloes around other galaxies.
Now, by utilising the unique space-based location of the NASA/ESA Hubble Space Telescope and its sensitive Advanced Camera for Surveys and Wide Field Camera 3, a team of astronomers has probed the halo surrounding the prominent giant elliptical galaxy Centaurus A , also known as NGC 5128, to unprecedented distances. They have found that its halo spreads far further into space than expected and does so in an unexpected form.