Speckle interferometry of nearby multiple stars

We present the results of diffraction-limited optical speckle interferometry and infrared bispectrum speckle interferometry of 111 double and 10 triple systems performed in 1998-1999 with the 6-m telescope of the Special Astrophysical Observatory in Zelenchuk. The observations concentrated on nearby close binaries discovered during the Hipparcos mission. Many nearby fast-orbiting low-mass binaries known before Hipparcos were also included in the program. New companions were first resolved in 4 systems: HIP 5245, ADS 3179, Kui 99, and ADS 16138. In addition to accurate relative positions, magnitude differences were measured for most of the pairs. We combined our results with the Hipparcos parallaxes to derive absolute magnitudes and spectral types for 63 binaries and 4 triples. Preliminary orbital elements and the mass-sum are derived for HIP 689, and improved orbits are presented for HIP 16602 (CHR117) and HIP 21280 (CHR17).