Abstract. The results of speckle interferometric observations of 104 binary and 6 triple stars performed at the BTA 6 m telescope in 2004 October are presented. Nearby low-mass stars are mostly observed for the program, among which 59 there are new binaries recently discovered by the Hipparcos astrometric satellite. Concurrently with the diffraction-limited position measurements we obtained 154 brightness ratio measurements of binary and multiple star components in different bands of the visible spectrum. New, first-resolved binaries are the symbiotic star CH Cyg with a weak companion at 0.043 ′′ separation and the pair of red dwarfs, GJ 913 = HIP 118212. In addition, we derived the orbital parameters for two interferometric systems: the CN-giant pair HD 210211 = HIP 109281 (P=10.7 yr) and the G2V-K2V binary GJ 9830 = HIP 116259 (P=15.7 yr).

No abstract

We continue the presentation of new orbits for Hipparcos binaries determined from regular speckle interferometric observations. Most of the data were collected in the period between 1998.77 and 2004.82 using the 6 m BTA telescope of the Special Astrophysical Observatory in Zelenchuk. New orbits are presented for six pairs: HIP 4809, HIP 4849, HIP 5531, HIP 19206, HIP 105947, and HIP 114922. One of the pairs, HIP 114922, has M dwarf components orbiting with a period of 19.72 yr. Two binaries, HIP 4809 and HIP 5531, have luminosity class IV components. The periods of the orbits range from 7.30 yr to 28.99 yr. All of the orbits can be considered definitive; however, the total mass error for the systems remains high, mainly due to Hipparcos parallax error.

No abstract

Speckle interferometry of the young binary system RW Aur was performed with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences using filters with central wavelengths of 550 nm and 800 nm and passband halfwidths of 20 nm and 100 nm, respectively. The angular separation of the binary components was 1.448 ′′ ± 0.005 and the position angle of the system was 255.9 o ± 0.3. at the observation epoch (JD 2 454 255.9). We find using published data that these values have been changing with mean rates of +0.002 ′′ /yr and +0.02 o /yr, respectively, over the past 70 years. This implies that the direction of the orbital motion of the binary system is opposite to the direction of the disk rotation in RW Aur A. We propose a physical model to explain the formation of circumstellar accretion disks rotating in the reverse direction relative to young binary stars surrounded by protoplanetary disks. Our model can explain the characteristic features of the matter flow in RW Aur A: the high accretion rate, small size of the disk around the massive component, and reverse direction of rotation.