Dynamics of Stellar Systems

The research in our group focuses on understanding the dynamical structure and evolution of stellar systems. In nearby galaxies and stellar clusters, we look for the 'fossil records' of their formation by constructing realistic dynamical models that fit their photometric and spectroscopic observations in detail. The latter include integral-field spectroscopy, observed motions and properties of individual stars, as well as (strong) gravitational lensing observations. Our individual research interests are listed below - for information, see group members' websites or look at some of our recent papers.

Group Members

Current group members and their research interests are listed below. We have some overlap with the MPIA Dynamics group, with regular meetings between members based at UniVie, ESO and MPIA.

Group Leader


Dr. Ryan Leaman
  • Dwarf galaxy evolution
  • Globular clusters as probes of accretion events
  • Semi-analytic models for galaxy assembly
Dr. Alice Zocchi
  • Dynamics of stellar systems
  • Formation and evolution of globular clusters
  • Stellar mass and intermediate-mass black holes in globular clusters
Dr. Edward Lilley   ERC
  • Analytical and numerical methods in classical dynamics
  • Photometric deprojection of external galaxy observations
  • Modelling the dark haloes of low-surface-brightness galaxies
Dr. Iris Breda
  • Mass assembly of disk galaxies
  • Spatially resolved spectral synthesis
  • Photometric decomposition
  • Kinematical modelling of galaxies

PhD students

Prem Kumar
  • Dynamical models
  • Dynamical evolution of galaxies

MSc Students

Shelley-Anne Harrisberg
  • Measuring supermassive black hole masses with molecular gas kinematics and black hole scaling relations with their host galaxies
  • Extra-galactic astronomy
  • Radio astronomy

Scientific computing consultant

Dr. Thomas I. Maindl
  • Mathematical programming and scientific computing
  • The DYNAMITE modeling tool for stellar population and dynamics
  • Simulation of collision processes
  • Late-stage planet formation
  • Asteroids and Earth defense

Former members

Francisco Aros   ERC
  • Dynamical signatures of IMBHs in globular clusters
  • Dark matter in dwarf spheroidal galaxies
Dr. Sabine Thater
  • Supermassive black holes in nearby galaxies
  • Galaxy kinematics from different tracers
  • Dynamical models of galaxies
  • Integral-field Spectroscopy

Research Opportunities

Open positions

No open positions at the moment. For PhD positions you can also check out open calls at the VISESS doctoral school.

Bachelor's and Master's projects

We regularly offer Bachelor and Master projects. Please contact us for more information.


A complete listing of all publications by members of our group can be found at ADS. Below we list a few key papers that highlight the work done by our group.

Total mass slopes and enclosed mass constrained by globular cluster system dynamics
2024, A&A, 681, A46
Veršič, Tadeja; Thater, Sabine; van de Ven, Glenn; Watkins, Laura L.; Jethwa, Prashin; Leaman, Ryan; Zocchi, Alice
Discrete Jeans modelling using globular cluster systems.
Effect of the initial mass function on the dynamical SMBH mass estimate in the nucleated early-type galaxy FCC 47
2023, A&A, 675, A18
Thater, Sabine; Lyubenova, Mariya; Fahrion, Katja; Martín-Navarro, Ignacio; Jethwa, Prashin; Nguyen, Dieu D.; van de Ven, Glenn
Effects of the initial mass function on the dynamical SMBH mass estimate.
Testing the robustness of DYNAMITE triaxial Schwarzschild modelling: The effects of correcting the orbit mirroring
2022, A&A, 667, A51
Thater, Sabine; Jethwa, Prashin; Tahmasebzadeh, Behzad; Zhu, Ling; den Brok, Mark; Santucci, Giulia; Ding, Yuchen; Poci, Adriano; Lilley, Edward; Tim de Zeeuw, P.; Zocchi, Alice; Maindl, Thomas I.; Rigamonti, Fabio; Yang, Meng; Fahrion, Katja; van de Ven, Glenn
The effects of correcting the orbit mirroring.
The stellar orbit distribution in present-day galaxies inferred from the CALIFA survey
2018, NatAs, 2, 233
Zhu, Ling; van de Ven, Glenn; van den Bosch, Remco; Rix, Hans-Walter; Lyubenova, Mariya; Falcón-Barroso, Jesús; Martig, Marie; Mao, Shude; Xu, Dandan; Jin, Yunpeng; Obreja, Aura; Grand, Robert J. J.; Dutton, Aaron A.; Macciò, Andrea V.; Gómez, Facundo A.; Walcher, Jakob C.; García-Benito, Rubén; Zibetti, Stefano; Sánchez, Sebastian F.
Characterization of the internal dynamical strucuture of a large sample of galaxies.
Triaxial orbit based galaxy models with an application to the (apparent) decoupled core galaxy NGC 4365
2008, MNRAS, 385, 647
van den Bosch, R. C. E.; van de Ven, G.; Verolme, E. K.; Cappellari, M.; de Zeeuw, P. T.
Introduction of the Triaxial Schwarzschild model and application to an elliptical galaxy.
Recovery of the internal orbital structure of galaxies
2008, MNRAS, 385, 614
van de Ven, G.; R.C.E. de Zeeuw, P. T.; van den Bosch, R. C. E.
Testing the Schwarzschild orbit recovery.
The Dynamical Distance and Intrinsic Structure of the Globular Cluster omega Centauri
2006, A&A, 445, 513
van de Ven, G.; R.C.E. van den Bosch; E.K. Verolme; P.T. de Zeeuw
An application of the Triaxial Schwarzschild code.

News & Activities


No new annoucments.

Last updated: 26.9.2020

Workshops and Meeting Organisation

Periodically we organise workshops for researchers interested in running dynamical models. Find out more information here.

Members of our group have organised conferences and workshops on a variety of topics:

Dynamical Reconstruction of Galaxies
Lorentz Center, Leiden, The Netherlands - 17-21 February 2020
Survival of Dense Star Clusters in the Milky Way System
Haus der Astronomie, Heidelberg - 19-21 November 2018
The Exciting Lives of Galactic Nuclei
Ringberg Castle - 26 February - 3 March 2017
MPIA Summer Conference 2015
Haus der Astronomie & MPIA, Heidelberg - 6-10 July 2015
3rd DAGAL Annual Meeting
MPIA Heidelberg - 23-27 March 2015
Gaia Challenge II
Haus der Astronomie / MPIA, Heidelberg - 27-31 October 2014
3rd CALIFA Busy Week
Haus der Astronomie, Heidelberg - 11-15 June 2012
Dynamics Meets Kinematic Tracers
Ringberg Castle - 10-14 April 2012

The stellar dynamics group at the University of Vienna has been busy developing our dynamical modelling code into a new form called DYNAMITE - i.e. dynamics, age and metallicity indicators tracing evolution. The latest release is available on the github page here. The documentation for the Dynamite code is available here.

The heart of DYNAMITE is the same triaxial Schwarzschild modelling code which has been successfully used for numerous scientific projects over the last 15 years.


Globular clusters (GCs) are the living fossils of the history of their native galaxies and the record keepers of the violent events that made them change their domicile. This project aims to mine GCs as living fossils of galaxy evolution to address fundamental questions in astrophysics:

  • Do satellite galaxies merge as predicted by the hierarchical build-up of galaxies? ⟷ Can we recover disrupted satellite galaxies from the GCs they left in their host?
  • What are the seeds of supermassive black holes in the centres of galaxies? ⟷ Do GCs harbour the intermediate mass black holes?
  • How did star formation originate in the earliest phases of galaxy formation? ⟷ Can the origin of multiple stellar populations in GCs be uncovered from distinct dynamical fossil signatures?
To answer these questions we will use population-dependent dynamical models to take full advantage of the emerging wealth of chemical and kinematical data on GCs.

ArcheoDyn is funded through a Consolidator Grant from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (under grant agreement No 724857).


GCs are dynamically complex stellar systems, with internal rotation and velocity dispersions that depend on both the intrinsic positions and masses of their stars. Yet it is unknown if this complexity is a signature of a central intermediate mass black hole (IMBH), relates to the observed multiple stellar populations in GCs, or arises from external gravitational effects. Following the tidal disruption of satellite galaxies, their GCs, and possibly their nuclei, remain as abundant and easily observed relics of the hierarchical build-up of galaxies. The evolution of galaxies to the present day can thus be unearthed by recovering the orbits of the GCs that are surrounding them.

In the next few years, astrometric data from ESA’s Gaia mission will allow for high-precision measurements of the 6D position-velocity vectors of the GCs in the Milky Way (MW). At the same time, numerous imaging and spectroscopy surveys are providing extensive catalogues of colours, metallicities and radial velocities of hundreds of GCs around nearby galaxies. To make use of this data, we are building tools to ascertain which GCs are accretion survivors and to recover their orbits.

The presence (or absence) of a central intermediate mass black hole (IMBH) or of multiple stellar populations might tell which GCs are accreted, and among these which are former galaxy nuclei. At the same time, detection of IMBHs is important as they are predicted seeds for supermassive black holes in the centres of galaxies; while the multiple stellar populations in GCs are crucial witnesses to the extreme modes of star formation in the early universe. However, for every putative dynamical IMBH detection in a GC so far, the expected kinematic and emission signatures have not been seen; also, the origin of multiple stellar populations within GCs still lacks any uncontrived explanation.

The quantity and quality of chemical and kinematical measurements of individual stars in GCs in the MW is currently dramatically increasing. This includes precision proper motion measurements of tens of thousands of stars in the inner parts of GCs based on Hubble Space Telescope (HST) data. Soon this will be complemented by Gaia proper motions of thousands of giant stars in the outer parts of the GCs. With the novel tools developed in this group, we aim to fully exploit this data to firmly establish the (non)presence of IMBHs and to disentangle the internal dynamics of the multiple stellar populations to decipher their origin.

With the synergy of new population-dynamics tools and exquisite chemo-kinematic data, the ArcheoDyn project aims to unlock the full potential of GCs as living fossils of the past of galaxies.

SFB: Tomography Across the Scales

As of 2022, our group is a member of the FWF-funded SFB project Tomography Across the Scales. This project connects scientists and mathematicians to tackle common challenges of extracting physical information from complex datasets using modern computing technology. The experimental groups have expertise spanning from applied optics to biophysics, medicine, and astrophysics. The mathematical groups are proficient in modelling, regularisation, and numerical optimisation. The mission of this consortium is to enable analysis of dynamic processes in nature across physical scales.

Advancing Extragalactic Archaeology through Novel Inversion Techniques

The goal of galactic archaeology is to reveal a galaxy’s past from observations in the present day i.e. viewed in the local Universe. By observing local galaxies we have access to the most precise data. In this SFB sub-project we will develop and apply novel inversion techniques to make accordingly precise inferences about a galaxy’s history. The proposed techniques will address short-comings of the current state-of-the-art techniques however they come at a much higher computational cost. Therefore, this work requires an interdisciplinary team with expertise in both galactic archeology and inverse problems.

Galaxies are shaped by a range of physical processes probing some of the most pressing questions in astrophysics. At the largest megaparsec scales, galaxies grow through the accretion of smaller systems, the details of which are sensitive to cosmology. At the kiloparsec scales, gravitational dynamics gives rise to complex morphologies, offering a window into the elusive dark matter. At the parsec scales of molecular clouds and star clusters, galaxies can be thought of as laboratories for understanding the physics of star formation. Detailed studies of the Milky Way’s past have revealed a great deal on all these topics, and we aim to extend this to galaxies beyond our own. This will advance the concept of galactic archaeology (a term usually reserved to the Milky Way) to the extra-galactic domain.