The oMEGACat Homepage

General Motivation and Project Overview

Omega Centauri (ω Cen, NGC 5139) is the most massive globular cluster of the Milky Way and is believed to be the stripped nucleus of an accreted dwarf galaxy. This makes it a unique laboratory to study both a witness of the merger history of the Milky Way and a nearby low-mass galactic nucleus.

In the oMEGACat project, led by Nadine Neumayer (MPIA) and Anil Seth (Univ. of Utah), we aim to disentangle its dynamics and its formation history by creating the largest spectroscopic, photometric, and astrometric dataset ever assembled for a globular cluster. Our data consists of two main catalogs: An extensive MUSE effort of more than 100 individual pointings providing spectra for more than 300,000 stars and giving us metallicities and line-of-sight velocities, and a Hubble Space Telescope-based catalog containing proper motion measurements and precise 7-band photometry for around 1.4 million individual stars.

The combined catalogs are already enabling a wide range of science projects, including studies of the cluster’s metallicity distribution, its multiple populations, its age-metallicity relation, and its central intermediate-mass black hole.

A three panel zoom into the center of Omega Centauri

People

Principal Investigators

Nadine Neumayer (Max Planck Institute for Astronomy, Heidelberg, Germany)
Anil Seth (University of Utah, Salt Lake City, USA)

Students and postdocs leading projects

Callie Clontz (Postdoc, Max Planck Institute for Astronomy, Heidelberg, Germany)
Simona di Stefano (PhD Student, INAF, Trieste, Italy)
Maximilian Häberle (Postdoc, European Southern Observatory, Garching near Munich, Germany)
Ishaan Kothiyal (Master Student, Max Planck Institute for Astronomy, Heidelberg, Germany)
Selina Nitschai (graduated PhD Student, Max Planck Institute for Astronomy, Heidelberg, Germany)
Peter Smith (PhD Student, Max Planck Institute for Astronomy, Heidelberg, Germany)
Stefano Souza (Postdoc, Max Planck Institute for Astronomy, Heidelberg, Germany)
Zixian Wang (Postdoc, University of Utah, Salt Lake City, USA)

In addition, a wide network of collaborators is actively contributing to the success of the project including:

Mayte Alfaro-Cuello (Univ. Central de Chile), Jay Anderson (STScI), Andrea Bellini (STScI), Aaron Dotter (Dartmouth), Stefan Dreizler (Göttingen), Anja Feldmeier-Krause (Vienna), Nikolay Kacharov (AIP Potsdam), Sebastian Kamann (Liverpool), Marilyn Latour (Göttingen), Mattia Libralato (INAF Padova), Antonino Milone (Univ. Padova), Renuka Pechetti (Liverpool), Glenn van de Ven (Vienna), Karina Voggel (Strassburg)

Data Access

The main catalogs created in this project are publicly available:

MUSE Spectroscopic Catalog: Download from IOP

HST Astro-Photometric Catalog: Download from Zenodo

Kinematic profiles and maps: Download from Zenodo

Publications

oMEGACat. I. MUSE Spectroscopy of 300,000 Stars within the Half-light Radius of ω Centauri Nitschai, Neumayer, Clontz et al. ApJ, 958, 8 (2023) ADS-Link
Fast-moving stars around an intermediate-mass black hole in ω Centauri Häberle, Neumayer, Seth et al. Nature, 631, 285 (2024) ADS-Link
oMEGACat. II. Photometry and Proper Motions for 1.4 Million Stars in Omega Centauri and Its Rotation in the Plane of the Sky Häberle, Neumayer, Bellini et al. ApJ, 970, 192 (2024) ADS-Link
oMEGACat. III. Multiband Photometry and Metallicities Reveal Spatially Well-mixed Populations within ω Centauri’s Half-light Radius Nitschai, Neumayer, Häberle et al. ApJ, 970, 152 (2024) ADS-Link
oMEGACat. IV. Constraining the Ages of Omega Centauri Subgiant Branch Stars with HST and MUSE Clontz, Seth, Dotter et al. ApJ, 977, 14 (2024) ADS-Link
oMEGACat V: Helium Enrichment in ω Centauri as a Function of Metallicity Clontz, Seth, Wang et al. ApJ, 984, 162 (2025) ADS-Link
oMEGACat. VI. Analysis of the Overall Kinematics of Omega Centauri in 3D: Velocity Dispersion, Kinematic Distance, Anisotropy, and Energy Equipartition Häberle, Neumayer, Clontz et al. ApJ, 983, 95 (2025) ADS-Link
oMEGACat. VII. Tracing Interstellar and Intracluster Medium of ω Centauri Using Sodium Absorptions Wang, Seth, Latour et al. ApJ, 994, 143 (2025) ADS-Link
oMEGACat. VIII. A Subpopulation Census of ω Centauri Clontz, Seth, Wang et al. (submitted to ApJ) ADS-Link

Last Update: December 15th, 2025 by M. Häberle