2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/5239Recent IR observations indicate that many massive binary systems present dust formation episodes, in regions close to the stars, during the periastron passage. These systems are known to be high-energy sources, and it is believed that wind collisions are the origin of the emission. In this work we show that wind collisions not only increase the X-ray emission but also allow dust formation. As an application we study eta Car, which presents, near periastron, an increase in the X-ray emission followed by a sudden decrease that lasts for about a month. We reproduce this feature calculating the optical depth due to dust formation along the orbital period.proceedings of "Winds, Bubbles and Explosions - in honour to John Dyson" - Patzcuaro, Mexico (Sep 2002)Astrophysicstext