Watch two real binary-star systems orbit a shared barycenter - switch between Sirius A/B and Alpha Centauri A/B and read the published periods, masses, and eccentricity.
The yellow point is the barycenter. The heavier star sits closer to it - that mass-ratio offset is what the panel's barycenter share line reports.
Switch presets to compare a bright main-sequence + white-dwarf pair (Sirius) against the nearest Sun-like pair (Alpha Centauri A/B) with a wider, more eccentric orbit.
Binary Star System 3D Explorer
Watch two published binary-star systems orbit a shared barycenter - switch between Sirius A/B (period 50.13 years) and Alpha Centauri A/B (period 79.76 years) and read the real masses and eccentricity in the facts panel.
Drag to orbit the view, scroll or pinch to zoom, and use Pause orbit to freeze the pair. Click either star or the yellow barycenter to see how the mass ratio sets how far each star sits from the shared center of mass.
The facts panel lists period, component masses, eccentricity, and - for Alpha Centauri - the 11.2 AU to 35.6 AU separation swing, so you can compare a compact visual binary against the nearest Sun-like pair.
- Two presets: Sirius A/B (P=50.13 yr, M_A=2.063 Msun, M_B=1.018 Msun) and Alpha Centauri A/B (P=79.76 yr, ~1.1 and ~0.9 Msun)
- Shared barycenter drawn and clickable; heavier star sits closer to it
- Eccentric orbit path shown for each preset (Sirius e~0.59, Alpha Cen e~0.52)
- Alpha Centauri panel reports periastron 11.2 AU and apastron 35.6 AU
- Play/Pause controls the orbit animation; fullscreen keeps the controls visible
- Runs fully in the browser with the vendored three.js engine - no account, no upload
Students connect the textbook barycenter idea to real pairs, amateur astronomers get a feel for why Sirius B stays hard to split visually, and curious readers see why Alpha Centauri's separation changes from Saturn-like to Pluto-like over one orbit.
| System | Period | Mass A | Mass B | Eccentricity |
|---|---|---|---|---|
| Sirius A/B | 50.13 years | 2.063 Msun | 1.018 Msun | about 0.59 |
| Alpha Centauri A/B | 79.76 years | about 1.1 Msun | about 0.9 Msun | about 0.52 |
Everything renders on your device with WebGL. The 3D engine loads once (about 0.7 MB) and is cached; no scene data is sent to a server.
The scene is an educational visualization of two published visual binaries - it does not solve n-body gravity, does not include Proxima Centauri as a third body, and does not claim telescope-true angular separations. On-screen sizes and separations are compressed for readability; the period, mass, and eccentricity figures in the panel are real.
For a step-by-step walkthrough, read the Binary Star System 3D Explorer step-by-step guide. The Space 3D collection also includes the Kepler Orbits 3D Explorer for ellipse laws, and the Stellar Magnitude 3D Explorer for brightness ranking.
Frequently Asked Questions
What does the Binary Star System 3D Explorer show?
Two real published binary pairs - Sirius A/B and Alpha Centauri A/B - orbiting a shared barycenter, with the facts panel listing the orbital period, component masses, and eccentricity for the active preset.
What is the yellow point in the middle?
The barycenter - the shared center of mass both stars orbit. The heavier star sits closer to it. For Sirius, with 2.063 and 1.018 solar masses, the white dwarf companion sits farther out than the primary.
Where do the Sirius numbers come from?
Bond et al. 2017 (Astrophysical Journal), combining Hubble Space Telescope imaging with ground-based astrometry: orbital period 50.13 years, Sirius A mass 2.063 solar masses, Sirius B mass 1.018 solar masses.
Where do the Alpha Centauri numbers come from?
Widely cited orbital elements give a period of 79.76 years and eccentricity about 0.52, with periastron 11.2 AU and apastron 35.6 AU. Component masses are about 1.1 and 0.9 solar masses (NASA SVS summarizes A as 1.1 Msun and B as 0.9 Msun).
Why does the orbit look elongated?
Both presets use nonzero eccentricity - about 0.59 for Sirius and about 0.52 for Alpha Centauri - so the path is an ellipse, not a circle. Alpha Centauri's separation swings from 11.2 AU at closest approach to 35.6 AU at farthest.
Is this an n-body gravity simulation?
No. It is an educational visualization that places two stars on a published Keplerian ellipse around the barycenter. It does not integrate forces, and it does not include Proxima Centauri. On-screen sizes and separations are compressed; the period, mass, and eccentricity figures are real.