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Chemically decoupled nucleus and the structure of the nuclear region in the spiral galaxy NGC 488

Sil'chenko, O. K.

The regular Sb-type galaxy NGC 488 was observed at the 6-meter telescope with the Multi-Pupil Field Spectrograph and found to have a chemically decoupled nucleus. Stellar population in the nucleus is twice richer in metals than that of the central bulge. An analysis of the isophotal shapes in the central part of the galaxy based on the images obta…

A test of Hipparcos parallaxes on multiple stars

Tokovinin, A. A.; Shatskii, N. I.

The dynamical parallaxes of visual binary stars with reliable orbits selected from the multiple star catalog are compared with their Hipparcos trigonometric parallaxes. 141 objects with errors in the Hipparcos parallaxes no larger than 2.5 mas are divided into three groups by the quality of their orbits and by the reliability of the Hipparcos comp…

Kinematic evidence for the wave nature of the Carina-Sagittarius arm

Dambis, A. K.; Rastorguev, A. S.; Sitnik, T. G. +2 more

Radial-velocity and (Hipparcos) proper-motion data are used to construct the residual space velocity field for OB associations in the Carina-Sagittarius arm. The azimuthal residual velocity component for most stars in the Sgr OB1, Ser OB1, Cru OB1, Cen OB1, and Car OB2 associations has the direction that is opposite to the Galactic rotation, while…

Relative intensities of intercombination lines in ultraviolet spectra of T Tauri stars

Lamzin, S. A.; Gomez de Castro, A. I.

Using the accretion shock wave model (Lamzin 1998), we calculate the relative intensities of the strongest intercombination lines in the range 1200-2000 Angstroms. We make a qualitative comparison of theoretical spectra with IUE low-resolution (~=6 Angstroms) spectra of T Tauri stars. We predict that several intercombination lines can be identifie…

The nature of visual components in 82 multiple systems

Shatskii, N. I.

We performed photoelectric BVR observations of 198 visual components in 82 multiple systems. We used a special technique for the measurements with a classical photometer. In our study of close visual binaries, we employed a new instrument - an astrometric scanning photometer; its design is described. Based on our photometric data in combination wi…

UV spectrophotometry and UBVJHKL photometry of the symbiotic nova V443 Her

Munari, U.; Kolotilov, E. A.; Popova, A. A. +1 more

The photometric UBVJHKL observations of the symbiotic star V443 Her performed during 1994-1997 and its UV spectrum obtained from IUE in October 1991 are presented. Over the last decade of dense photometric observations, the U light curve can be described by a sinusoid with P = 598 days. At the same time, no periodic variations (with P or P/2) have…

Is it possible to observe the emission from the boundary layers of FU Ori stars?

Rossi, C.; Giovannelli, F.; Vittone, A. A. +3 more

Our estimates show that the optical depth of the stellar wind from the FU Ori stars FU Ori, V1057 Cyg, and Z CMa in the Balmer and Paschen contunua can be greater than unity. It is probably for this reason that no optical and ultraviolet emission is observed from the innermost and hottest regions of these objects the boundary layers of accretion d…

The multishell complex in Cygnus: High-velocity motions in the nebula Simeiz 55

Lozinskaya, T. A.; Esipov, V. F.; Sitnik, T. G. +3 more