juliensimon/globular-star-clusters

---
license: cc-by-4.0
pretty_name: "Milky Way Globular Star Clusters"
language:
- en
description: "Comprehensive catalog of 170 Milky Way globular clusters merging the Harris (2010) and Baumgardt databases. Includes positions, distances, metallicities, masses, velocity dispersions, structural parameters, and photometry."
task_categories:
- tabular-classification
- tabular-regression
tags:
- space
- globular-clusters
- stars
- milky-way
- astronomy
- open-data
- tabular-data
size_categories:
- n<1K
configs:
- config_name: default
data_files:
- split: train
path: data/globular_star_clusters.parquet
default: true
---

# Milky Way Globular Star Clusters

*Part of the [Astronomy Datasets](https://huggingface.co/collections/juliensimon/astronomy-datasets-67ac2ada12aceb39f8feca3b) collection on Hugging Face.*

A comprehensive catalog of **170** Milky Way globular clusters, merging two authoritative sources:
the [Harris (2010 edition)](https://physics.mcmaster.ca/~harris/mwgc.dat) catalog for metallicities and
photometry, and the [Baumgardt globular cluster database](https://people.smp.uq.edu.au/HolgerBaumgardt/globular/)
for dynamical masses, velocity dispersions, and structural parameters from N-body model fits to
Gaia DR3 proper motions and HST data.

## Dataset description

Globular clusters are ancient, gravitationally bound collections of stars orbiting the Milky Way.
They are among the oldest objects in the Galaxy (10--13 Gyr), with typical masses of
10⁴--10⁶ M☉ and half-light radii of a few parsecs. Their metallicities, dynamics,
and spatial distribution encode the formation and assembly history of the Milky Way.

This dataset combines Harris (2010) photometric and chemical data with Baumgardt's dynamical
parameters derived from N-body fits to modern astrometric and spectroscopic data, providing
the most complete per-cluster view available.

## Schema

| Column | Type | Description |
|--------|------|-------------|
| `name` | string | Cluster name (e.g. "NGC 104", "Pal 5") |
| `ra_deg` / `dec_deg` | float64 | Position in decimal degrees (J2000) |
| `distance_kpc` | float64 | Distance from the Sun (kpc) |
| `distance_err_kpc` | float64 | Distance uncertainty (kpc) |
| `distance_gc_kpc` | float64 | Galactocentric distance (kpc) |
| `metallicity_fe_h` | float64 | Metallicity [Fe/H] (dex) |
| `reddening_e_bv` | float64 | Foreground reddening E(B−V) |
| `apparent_mag_v` | float64 | Apparent integrated V magnitude |
| `absolute_mag_v` | float64 | Absolute integrated V magnitude |
| `color_u_b` / `color_b_v` / `color_v_r` / `color_v_i` | float64 | Integrated color indices |
| `spectral_type` | string | Integrated spectral type |
| `ellipticity` | float64 | Projected ellipticity e = 1−b/a |
| `mass_msun` | float64 | Total cluster mass (M☉) |
| `mass_err_msun` | float64 | Mass uncertainty |
| `mass_to_light_v` | float64 | V-band mass-to-light ratio (M☉/L☉) |
| `log_initial_mass_msun` | float64 | Log₁₀ initial mass (M☉) |
| `dissolution_time_gyr` | float64 | Predicted dissolution time (Gyr) |
| `core_radius_pc` | float64 | Core radius (pc) |
| `half_light_radius_pc` | float64 | Projected half-light radius (pc) |
| `half_mass_radius_pc` | float64 | 3D half-mass radius (pc) |
| `tidal_radius_pc` | float64 | Tidal radius (pc) |
| `log_central_density_msun_pc3` | float64 | Log₁₀ central density (M☉/pc³) |
| `log_half_mass_density_msun_pc3` | float64 | Log₁₀ half-mass density (M☉/pc³) |
| `log_half_mass_relaxation_time_yr` | float64 | Log₁₀ half-mass relaxation time (yr) |
| `velocity_dispersion_km_s` | float64 | Central velocity dispersion (km/s) |
| `escape_velocity_km_s` | float64 | Central escape velocity (km/s) |
| `radial_velocity_km_s` | float64 | Heliocentric radial velocity (km/s) |
| `anisotropy_central` / `anisotropy_half_mass` | float64 | Velocity anisotropy (η) |
| `rotation_amplitude_km_s` | float64 | Rotation amplitude (km/s) |
| `rotation_probability_pct` | float64 | Probability of significant rotation (%) |
| `mass_function_slope` | float64 | Present-day mass function slope (α) |
| `n_radial_velocity_stars` | int | Stars with radial velocity measurements |
| `n_proper_motion_stars` | int | Stars with proper motion measurements |
| `core_collapsed` | bool | Core-collapsed cluster (Harris) |
| `concentration_harris` | float64 | King-model concentration c = log(r_t/r_c) |

## Quick stats

- **170** Milky Way globular clusters
- **167** with dynamical mass estimates (7.46e+02–3.94e+06 M☉)
- **152** with metallicity measurements (-2.37 to 0.00 dex)
- **167** with central velocity dispersions
- **29** identified as core-collapsed

## Usage

```python
from datasets import load_dataset

ds = load_dataset("juliensimon/globular-star-clusters", split="train")
df = ds.to_pandas()

# Most massive clusters
massive = df.nlargest(10, "mass_msun")[["name", "mass_msun", "metallicity_fe_h"]]

# Metal-poor vs metal-rich populations
metal_poor = df[df["metallicity_fe_h"] < -1.5]
metal_rich = df[df["metallicity_fe_h"] >= -1.5]

# Core-collapsed clusters
cc = df[df["core_collapsed"]]

# Mass-metallicity relation
import matplotlib.pyplot as plt
plt.scatter(df["metallicity_fe_h"], df["mass_msun"].apply(lambda x: x if x else None))
plt.xlabel("[Fe/H]"); plt.ylabel("Mass (M☉)"); plt.yscale("log")
```

## Data sources

1. **Harris (2010 edition)**: [McMaster Globular Cluster Catalog](https://physics.mcmaster.ca/~harris/mwgc.dat).
Please cite [Harris (1996), AJ 112, 1487](https://ui.adsabs.harvard.edu/abs/1996AJ....112.1487H) — 2010 edition.

2. **Baumgardt Globular Cluster Database**: [https://people.smp.uq.edu.au/HolgerBaumgardt/globular/](https://people.smp.uq.edu.au/HolgerBaumgardt/globular/).
Please cite [Baumgardt & Hilker (2018), MNRAS 478, 1520](https://ui.adsabs.harvard.edu/abs/2018MNRAS.478.1520B).

## Related datasets

- [open-star-clusters](https://huggingface.co/datasets/juliensimon/open-star-clusters) — Milky Way open clusters
- [stellar-streams](https://huggingface.co/datasets/juliensimon/stellar-streams) — Tidal stellar streams
- [pulsars](https://huggingface.co/datasets/juliensimon/pulsars) — ATNF Pulsar Catalogue

## Pipeline

Source code: [juliensimon/space-datasets](https://github.com/juliensimon/space-datasets)

## Citation

```bibtex
@dataset{globular_star_clusters,
author = {Simon, Julien},
title = {Milky Way Globular Star Clusters},
year = {2026},
publisher = {Hugging Face},
url = {https://huggingface.co/datasets/juliensimon/globular-star-clusters},
note = {Merged from Harris (1996, 2010 edition) and Baumgardt et al. globular cluster databases}
}
```

## License

[CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)