1996A&A...309..163R

This paper is the second in a series, following the one by Richichi et al. (1994a, hereafter Paper I), reporting discoveries of new binary stars in the course of routine lunar occultation programs at the TIRGO and Calar Alto observatories, or re-observations of known or suspected binaries where only incomplete information was available. We report on a total of 15 sources. In the following eight cases, we detected a companion for the first time: SAO 93127, SAO 93195, SAO 95677, SAO 96110, SAO 97246, SAO 97258, SAO 183637, AG +15 845. For two stars, SAO 76131 and SAO 184822, we confirm previous reports of binarity, with our IR measurements complementing existing visual information. In the case of the five stars SAO 93484, SAO 96746, SAO 128467, SAO 157923 (α Vir), and SAO 162413, a companion had also been previously observed, but we could not detect it in our observation. Our negative detection in most of these cases provides a constraint on the characteristics of the companion. The projected separations in our positive results range from 0.79" to 0.006", and the range of brightness ratios from ≃1:1 to 1:150. The faintest companion has K≃11. The performance of the lunar occultations technique offers a valid complement to other more modern methods such as speckle interferometry and long baseline interferometry, and in fact many of the stars in our list could not be resolved by previous attempts using these latter techniques. In addition to standard observations by fast photometers, in this paper we include and describe the routine use of an IR array detector to record lunar occultations, which offered significant improvement in sensitivity.