Quadruple System
Two Binaries Orbiting a Common Barycentre
The Mizar archetype: two tight binary pairs (AB and CD) co-orbiting a system-wide barycentre. Each pair's internal orbital period is far shorter than the wide outer orbit — required for long-term stability.
Stable multi-star systems are always hierarchical — composed of nested pairs. A flat 4-star arrangement (all four roughly the same distance apart) is dynamically chaotic and ejects members within a few orbital periods.
The rule of thumb: outer separation ≥ 100× inner. This makes each tight pair's gravity dominate locally while the wider orbit feels them as a single point mass.
Elite Dangerous includes many quadruple+ systems — some have 5, 6, or even 7 stellar bodies. The system map shows the hierarchy as a tree: each barycentre marker indicates a sub-pair that orbits something larger.
Drop into a tight binary inside a quadruple and you'll see two stars bigger than your view. The other pair is somewhere else entirely — sometimes hours of supercruise away.
Look for systems with multiple A B C D designations in the nav panel — these are nearly always quadruple-or-higher hierarchies.
| Architecture | Description | Stability | Example |
|---|---|---|---|
| 2 + 2 | Two tight binaries on a wide mutual orbit | Stable if outer / inner ratio > 100 | Mizar (ζ UMa) |
| 3 + 1 | Hierarchical triple + distant fourth companion | Stable with strong hierarchy | HD 91962 |
| Trapezium | Four young stars in a loosely bound cluster | Often dynamically unstable | θ¹ Orionis core |
| Higher-order | 5+ stars (quintuples, sextuples) | Always nested hierarchies | Castor (6 stars), AR Cassiopeiae (7) |