With the publication of five new data packages, ESA’s Gaia offers numerous fresh and enhanced views into the universe and beyond. The mission discovers, among other things, 500,000 new, dim stars in a huge cluster. The new Gaia stars discovered in Omega Centauri reside in one of the sky’s densest populations.
Left: Dim stars in Omega Centauri with brightness between 18 and 21 magnitudes from Gaia Data Release 3. Each star is represented as a dot with the same brightness to show the star density. A “hole” is visible in the centre of the cluster, because the normal observation mode cannot account for the faint stars in this region. Right: The same image, but extended with data from the Gaia Focused Product Release. Using the new method, the faint stars are no longer “missed”, the data are more complete. Image Credit: ESA/Gaia/DPAC. Acknowledgement: Stefan Jordan, Katja Weingrill, Alexey Mints, Tineke Roegiers. Visualisation: Gaia Sky, Toni Sagristà
The third data release from Gaia included information on more than 1.8 billion stars, creating a rather comprehensive picture of the Milky Way and beyond. However, the mapping still had some holes. Gaia’s standard observation mode hit its limits in regions of the sky that were very densely populated with stars, leaving these relatively unexplored and excluding stars that shone less brilliantly than their numerous neighbors.
The best illustration of this is globular clusters. Given that these clusters are among the oldest things in the universe, they are very useful to researchers studying the history of the cosmos. Unfortunately, telescopes trying to acquire a good picture might be overwhelmed by their luminous centers, which are packed with stars. As a result, they continue to be missing components in the universe maps.
Gaia chose Omega Centauri, the biggest globular cluster visible from Earth and a superb illustration of a ‘typical’ cluster, to fill in the gaps in the maps. Gaia enabled a unique observation mode that captured two-dimensional photos of the Sky Mapper instrument rather than merely concentrating on individual stars as it would ordinarily do.
In Omega Centauri, we discovered over half a million new stars Gaia hadn’t seen before—from just one cluster!
Dr. Katja Weingrill, Study Lead Author and Principal Investigator, Leibniz Institute for Astrophysics Potsdam
Dr. Alexey Mints, study co-author and Gaia Collaboration member, added, “It is not just patching up holes in our mapping, although this is valuable in itself. Our data allowed us to detect stars that are too close together to be properly measured in Gaia’s regular pipeline. With the new data we can study the cluster’s structure, how the constituent stars are distributed, how they are moving, and more, creating a complete large-scale map of Omega Centauri. It is using Gaia to its full potential—we have deployed this amazing cosmic tool at maximum power.”
Since the Sky Mapper images were initially primarily meant for calibration purposes, this result not only fulfills but substantially exceeds Gaia’s intended capability. To make sure that all of Gaia’s equipment was functioning properly, the crew adopted an observing mode.
Dr. Weingrill further stated, “We did not expect to ever use it for science, which makes this result even more exciting.”
Eight additional places are being investigated by Gaia in this way, and the findings will be presented in Gaia Data Release 4. To determine the age of the galaxy, find its center, determine whether it has undergone any previous collisions, confirm how stars change over the course of their lifetimes, constrain our models of galactic evolution, and ultimately infer the potential age of the universe itself, these data will help astronomers truly understand what is happening within these cosmic building blocks.
The new release of Gaia also includes the identification of over 380 potential gravitational lenses, an improvement in the precision of the orbits of over 150,000 asteroids within the solar system, a map of the Milky Way disk made by following faint signals in starlight, and a description of the dynamics of 10,000 pulsating and binary red giant stars.
Journal Reference
Weingrill, K., et al. (2023) Gaia Focused Product Release: Sources from service interface function image analysis. Half a million new sources in omega Centauri. Astronomy & Astrophysics. doi:10.1051/0004-6361/202347203