  The binary LS 5039 is a non-thermal X-ray emitter that presents jet-like
radio structures, and is also one of the most misterious TeV sources in our
Galaxy. The presence of an O-type star in LS 5039 implies that the non-thermal
emitter must be embedded in a strong stellar wind, and the role of the latter
could be relevant for the understanding of the high-energy behavior of the
source. In this work, we show that the lack of absorption features in the soft
X-ray spectrum of LS 5039 can constrain strongly the parameters that describe
the wind, and ultimately the location of the non-thermal emitter.
