Astronomical evidence
PSR B1620-26 b belongs to a system containing a pulsar and a white dwarf in the globular cluster M4. Pulsar timing first revealed the gravitational influence of a distant companion. Hubble observations of the white dwarf helped constrain the system’s orientation and the companion’s planetary mass. Sigurdsson and colleagues inferred a mass of roughly 2.5 ± 1 Jupiter masses, recorded in the saved catalog as about 795 ± 318 Earth masses. The proposed history involves an old planet and dynamical encounters in a dense stellar environment. That evolutionary history is an inference, not a directly witnessed sequence. The white dwarf’s comparatively young cooling age does not date the planet’s formation. Cooling age measures the time since the remnant entered that stage, while a planet can predate the interaction that assembled its current system. This distinction allows an ancient planet to accompany a younger-looking remnant.
The illustrated viewpoint
Asymmetric spiral carapace in a still, inward-folded meditative pose. A fictional moon in a planet–pulsar–white-dwarf system within M4. The rocky foreground is an invented moon. The dense starfield evokes the cluster environment, but individual stellar positions and brightnesses are not a simulated sky. The pulsar does not appear as an enormous visible beacon.
The rocky foreground is an invented moon. The dense starfield evokes the cluster environment, but individual stellar positions and brightnesses are not a simulated sky. The pulsar does not appear as an enormous visible beacon. All depicted life is fictional. The visual connection to the cosmos is an artistic theme, not a claimed biological mechanism.
Catalog measurements & sources
Host: PSR B1620-26. Snapshot: 25 September 2026. Errors, limits and source provenance are retained. Calculated values and model estimates are not direct measurements. Unknown is not zero; equilibrium temperature is not surface temperature.
| Quantity / unit | Value / reported errors | Source |
|---|---|---|
| Radius · Earth radii | 13.3 | Calculated Value |
| Mass · Earth masses | 794.575 (+317.83 / -317.83) | Sigurdsson et al. 2003 |
| Density · g/cm³ | 1.86 | Calculated Value |
| Orbital period · days | Unknown | Not supplied |
| Orbital semimajor axis · AU | 23 | Sigurdsson et al. 2003 |
| Eccentricity | Unknown | Not supplied |
| Inclination · degrees | Unknown | Not supplied |
| Irradiation · Earth flux | Unknown | Not supplied |
| Equilibrium temperature · K | Unknown | Not supplied |
| Stellar effective temperature · K | Unknown | Not supplied |
| Stellar radius · Solar | Unknown | Not supplied |
| Stellar mass · Solar | 1.35 | Sigurdsson et al. 2003 |
| Stellar luminosity · log Solar | Unknown | Not supplied |
| Stellar age · Gyr | Unknown | Not supplied |
| Stellar metallicity · dex | Unknown | Not supplied |
| Distance · pc | Unknown | Arzoumanian et al. 1996 |