The archetype of colliding-wind binary (CWB) systems is the 7.9-year period WR+O binary system WR140 (HD193793) where the stellar separation varies between ~ 2 AU at periastron to ~ 30 AU at apastron. The binary is frequently considered a textbook example of the colliding-wind phenomenon. The binary consists of a carbon-sequence Wolf-Rayet (WC7) star orbiting a more massive and luminous O4-5 main-sequence companion. The system’s high eccentricity and rather favorable inclination help to probe different regions of the Wolf-Rayet wind and, at the same time, the profound change of conditions in the wind-wind collision zone at the times of periastron passage. This change is mainly reflected in rapid formation of dust clouds and can be detected as gigantic IR outbursts occurring on a strictly periodic (once per orbit) timescale.

Workshop report by José Ribeiro

WR 140 page of Peredur Williams
Observatorio del Teide weather station
Observatorio del Teide Meteorología
Webcam (MONS right side in the background)

The status of the system as a strong nonthermal, variable radio source, as well as an extremely bright (for a WR star) X-ray source makes WR140 an ideal laboratory for studying the properties of hot stellar winds. The almost perfectly phase-dependent behavior of the system in radio and X-rays is remarkable.

The system has a relativ long period and periastron passage. That means professional astronomers have problems to obtain a lot of data during periastron. Due to its brightness amateurs can obtain reasonable data and WR 140 gives a good oportunity to collaborate with the pro's. We are looking for interested amateur spectroscopists for data contribution. Don't hesitate to give information about your spectra and discuss results in our WR140-Forum.

You can find messages from the professional astronomers about WR 140 in their Statements.