We present an update to the frequency analysis method for measuring the properties of a galactic bar. The method involves computing the fundamental frequencies of orbits in rotating, N-body-derived potential models, classifying the stars as members of bar supporting orbits, and finding the extent of the apo-centre distribution. In this work, we apply an updated classification criterion designed to isolate the so-called "Warm" inner Lindblad resonance (ILR) orbits. These orbits have been shown to contain the looped x1 orbits, which dominate the "shoulder regions" of the bar and largely contribute to the radial extent. We apply this method to existing Gaia, APOGEE, and OGLE data of more than 200,000 stars to constrain the properties of the Milky Way bar. We find that multiple bar lengths and pattern speeds are consistent with the data to within 5 percent.
- Self-consistent dynamical modelling of the Milky Way bar with orbital frequency analysis
- Zachary Langford (Corresponding Author)Robyn Sanderson (Author)Madeline Lucey (Author)Jason Alexander Sergio Hunt (Author)
- Monthly Notices of the Royal Astronomical Society, Vol.551(1), stag1435
- OXFORD UNIV PRESS; OXFORD
- 21
- 31/07/2026
- 09/2026
- 21/07/2026
- Ernest Rutherford Fellowship, ST/Z510245/1, UK Research and Innovation (United Kingdom, Swindon) - UKRI
- ZL thanks Sioree Ansar, Carrie Filion, Francesca Fragkoudi, Sarah Pearson, Michael Petersen, and Adrian Price-Whelan for useful discussions that have greatly improved this work. ZL also thanks the anonymous referee for comments that helped to improve this manuscript. ZL and RES were supported by the National Science Foundation grant AST-2007232, Sloan Foundation award FG-2023-20669, and Simons Foundation grant 1018462 in the completion of this work. ML acknowledges the support of the National Science Foundation under Award No. 2303831. JH acknowledges the support of a UKRI Ernest Rutherford Fellowship ST/Z510245/1. ZL acknowledges the use of the University of Pennsylvania General Purpose Cluster, on which the computations in this paper were carried out.
- 991146795302346; WOS:001847503900001
- © The Author(s) 2026. Published by Oxford University Press on behalf of Royal Astronomical Society.
- School of Maths and Physics
- English
- Journal article