A test for the theory of colliding winds: the periastron passage of 9Sgr

We propose to monitor the Xray emission of the 8.6year period, highlyeccentric (e 0.7) Otype binary 9Sgr around its forthcoming periastronpassage. 9Sgr is known to display a synchrotron radio emission due torelativistic electrons accelerated in the windwind collision region. This windinteraction zone is expected be in the adiabatic regime and the Xray fluxshould thus scale as the inverse of the orbital separation. Observations nearperiastron and at subsequent orbital phases will allow us to test this scenarioand to search for the possible presence of nonthermal Xray emission, therebysetting constraints on the wind interaction phenomenon in a yet unexplored partof the parameter space. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]