2000A&A...358L..55Z

A remarkable correlation between the Hα emission line and the radio behaviour of LS I+61°303 over its modulation is discovered. The radio outburst peak is shifted by a quarter of the modulat ion period (about 400 days) with respect to the equivalent width of the Hα emission line variability. The onset of the LS I+61°303 radio outbursts varies in phase with the changes of the Hα emission line, at least during the increase of Hα equivalent width. This is the first clear correlation between the emission associated to the compact object and the Be circumstellar disk in a Be/X-ray binary system.