Binary star orbits

The United States Naval Observatory (USNO) currently maintains the main database of double (and multiple) stars, called the Washington Double Star Catalog. For a number of such objects, a sufficient number of observations has been accumulated over time to form an idea the motion of the components with respect to each other.

Assuming that the motion of a component of a binary star with respect to the other is Keplerian, the orbit is an ellipse whose shape and orientation, as well as the motion along it, are completely determined by a small number of parameters. A typical set of such parameters consists of the period of the motion and six orbital elements such as the semi major-axis and eccentricity of the orbit (which determine its shape), the longitude of the ascending node, inclination, and argument of the periapsis (which determine the orientation of the orbit in space), and the time of passage at the periapsis.

The USNO maintains an ever-growing database of such parameters for binary stars (or subsystems of multiple stars) whose relative motions are known: the Sixth Catalog of Orbits of Visual Binary Stars. This page presents graphical representations of these orbits, similar to the ones provided by the USNO (through the P links), that may be of interest to binary star enthusiasts.

The orbit diagrams (corresponding to the orbits database as of 2018-08-11) are accessible from the scrollable table below, where the WDS identifier links to the corresponding PDF file. Alternatively, they can be downloaded all at once as a zip archive (30 MB) or compressed tar archive (24 MB).