J/A+A/706/A130 MW GCs physical parameters with OrbIT code (De Leo+, 2026)
Globular clusters in ORBIT: Complete dynamical characterisation of the Milky Way
globular cluster population through updated orbital reconstruction.
De Leo M., Zoccali M., Olivares-Carvajal J., Acosta-Tripailao B., Gran F.,
Contreras-Ramos R.
<Astron. Astrophys. 706, A130 (2026)>
=2026A&A...706A.130D 2026A&A...706A.130D (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, globular
Keywords: methods: numerical - celestial mechanics - Galaxy: formation -
globular clusters: general - Galaxy: kinematics and dynamics -
Galaxy: structure
Abstract:
In hierarchical structure formation, the content of a galaxy is
determined both by its in-situ processes and by material added via
accretions. Globular clusters in particular represent a window for the
study of the different merger events that a galaxy underwent.
Establishing the correct classification of in-situ and accreted
tracers, and distinguishing the various different progenitors that
contributed to the accreted population are important tools to deepen
our understanding of galactic formation and evolution.
Our aim is to refine our knowledge of the assembly history of the
Milky Way by studying the dynamics of its globular cluster population
and establishing an updated classification among in-situ objects and
the different merger events identified.
We used a custom built orbit integrator to derive precise orbital
parameters, integrals of motions and adiabatic invariants for the
globular cluster sample studied. By properly accounting for the
rotating bar, which transforms the underlying model in a time-varying
potential, we proceeded to a complete dynamical characterisation of
the globular clusters.
We present a new catalogue of clear associations between globular
clusters and structures (both in-situ and accreted) in the Milky Way,
and a full table of derived parameters. By using all dynamical
information available, we were able to attribute previously
unassociated or misclassified globular clusters to the different
progenitors, including those responsible for the Aleph, Antaeus,
Cetus, Elqui, and Typhon merger events.
By using a custom built orbit integrator and properly accounting for
the time-varying nature of the Milky Way potential, we have shown the
depth of information that can be extracted from a purely dynamical
analysis of the globular clusters of our Galaxy. By merging our
dynamical analysis with complementary chronochemical studies, we will
be able to uncover the remaining secrets of the accretion history of
the Milky Way.
Description:
IDs and derived orbital parameters for the sample of clusters of
https://people.smp.uq.edu.au/HolgerBaumgardt/globular/ plus ESO 93-08,
Gran 4, Patchick 122 and VVV-CL002. The orbital parameters computed
with the code OrbIT are: energy, angular momentum Lz, perpendicular
angular momentum, pericentre radius, apocentre radius, eccentricity,
maximum excursion from the plane of the disc, parallel action,
perpendicular action, and orbital circularity.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablec1.dat 186 169 Orbital parameters, IoMs, adiabatic invariants
and derived quantities used for GCs analysis
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See also:
J/A+A/695/A211 : Galactic bar/bulge traced by RRLs (Prudil+, 2025)
J/A+A/689/A240 : VVV catalog and light curves of bulge RRab Lyrae
(Zoccali+, 2024)
J/A+A/687/A312 : Kinematics of bulge RR Lyrae stars
(Olivares Carvajal+, 2024)
J/A+A/684/A37 : Walk on the Retrograde Side (WRS) project
(Ceccarelli+, 2024)
J/A+A/683/A167 : 5 recently discov. globular clusters MUSE analysis
(Gran+, 2024)
J/A+A/670/L2 : Gaia DR3 of substructure in the stellar halo (Dodd+, 2023)
J/A+A/665/A58 : Substructure in stellar halo near the Sun. II.
(Ruiz-Lara+, 2022)
J/A+A/665/A57 : Substructure in the stellar halo near the Sun. I.
(Lovdal+, 2022)
J/A+A/618/A147 : Fraction of bulge metal poor & metal rich stars
(Zoccali+, 2018)
J/A+A/562/A71 : Chemical abundances of solar neighbourhood dwarfs
(Bensby+, 2014)
J/MNRAS/505/5978 : Gaia EDR3 view on Galactic globular clusters
(Vasiliev+, 2021)
J/MNRAS/491/3251 : Globular clusters in the inner Galaxy
(Perez-Villegas+, 2020)
J/MNRAS/484/2832 : Proper motions of Milky Way globular clusters
(Vasiliev, 2019)
J/MNRAS/478/1520 : Milky Way globular clusters data (Baumgardt+, 2018)
J/ApJ/885/3 : Membership in 12 stellar streams from DES (Shipp+, 2019)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
II/337 : VISTA Variables in the Via Lactea Survey DR1 (Saito+, 2012)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- ID Globular cluster identifier name (GC_ID)
14- 23 F10.6 kpc Rperi Pericentre radius (Peri)
25- 33 F9.6 kpc e_Rperi ? Error on the pericentre radius (Peri_err)
35- 44 F10.6 kpc Rapo Apocentre radius (Apo)
46- 55 F10.6 kpc e_Rapo ? Error on the apocentre radius (Apo_err)
57- 64 F8.6 --- e Orbital eccentricity (Ecc)
66- 73 F8.6 --- e_e ? Error on the eccentricity (Ecc_err)
75- 84 F10.6 kpc Zmax Maximum Z excursion from the Galactic plane
(Zmax)
86- 95 F10.2 km2/s2 Etot Total mechanical energy (Etot)
97-108 F12.6 kpc.km/s Lz Angular momentum around the Z axis (Lz)
110-130 F21.15 kpc.km/s Lperp Perpendicular angular momentum (Lperp)
132-153 F22.19 --- Jpara Action parallel to the Z axis (Jpara)
155-176 F22.19 --- Jperp Action perpendicular to the Z axis (Jperp)
178-186 F9.6 --- Epsilon Orbital circularity (circularity) (1)
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Note (1): Defined as the ratio of Lz over the angular momentum of a maximally
rotating planar orbit having same specific energy as tracer
Lzmax(E), (i.e see method section).
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Acknowledgements:
Michele De Leo, micheledl89(at)gmail.com
(End) Michele De Leo [UniBo, Italy], Luc Trabelsi [CDS] 16-Dec-2025