Dark-speckle coronagraphic detection of binary stars in the near-IR

In this paper, we present the first attempt to obtain images of binary stars in the near IR using the dark-speckle method on the 3.6 m telescope at La Silla. Promising results are presented, despite the effect of the detector high read-out noise affecting the efficiency of speckle observations. We give some comparisons with the long exposure method. We derive in these data a reliable limit of detection for binary star companions, around m_K < 4 stars, which is about Δm_K ≈ 6-7 for angular separations ranging from 0.5" to 0.9".