Today, ESA's Gaia mission releases a goldmine of knowledge about our galaxy and beyond in its 'focused product release'. Among other findings, the star surveyor reveals more than half a million faint stars in a massive cluster – stars the telescope had not seen before.
Gaia’s third data release (DR3) contained data on over 1.8 billion stars, building a pretty complete view of the Milky Way and beyond. However, there remained gaps in our mapping. Gaia had not yet fully surveyed areas of sky that were especially densely packed with stars, leaving these comparatively unexplored – and overlooking stars shining less brightly than their many neighbours.
To patch the gaps in our maps, Gaia selected Omega Centauri, the largest globular cluster that can be seen from Earth and a great example of a ‘typical’ cluster. Rather than just focusing on individual stars as it typically would, Gaia enabled a special mode to truly map a wider patch of sky surrounding the cluster’s core every time the cluster came into view.
The team revealed 526 587 new Gaia stars from this cluster alone, detecting stars that lie too close together to be measured in the telescope’s regular pipeline and those in the cluster core that are up to 15 times fainter than previously seen. The new data reveal 10 times more stars in Omega Centauri; this new knowledge will enable researchers to study the cluster’s structure, how the constituent stars are distributed, how they’re moving, and more, creating a complete large-scale map of Omega Centauri.
Gaia is exploring nine crowded regions in this way, with the full results expected in Gaia Data Release 4.
The image of Omega Centauri in this infographic, in the inset circle, shows the cluster as observed by Gaia. Stars of all brightnesses are visible within the cluster.
Alt-text: This infographic is set on a background image of the plane of the Milky Way. Omega Centauri is visible in the sky as a small bright dot in the centre of the frame; an inset circle highlights and magnifies the cluster, showing its central region as seen by Gaia. Statistics relating to the new Gaia data are featured on the right.
Acknowledgments: Based on the paper "Gaia Focused Product Release: Sources from Service Interface Function Image Analysis – Half a Million New Sources in Omega Centauri" by Gaia Collaboration, K. Weingrill et al.; Image of Omega Centauri created by Stefan Jordan and Toni Sagristà; Graphic produced by ATG under contract to ESA.