Volume 19, Issue 3-4

High resolution spectra of M-type supergiant μ Cep are analyzed. The movements in the atmosphere of this star are highly supersonic and variable with depth. The lines forming in deeper layers show the widths corresponding to 30 kms −1 . The lines forming in outer layers are much wider, 50 kms −1 . At the same time, the microturbulent velocity (ξ t ) is low, from 4.0 to 4.5 kms −1 . The atmosphere of μ Cep is slightly metal deficient with [Fe/H]≈-0.4.

Photospheric parameters and chemical composition are determined for the single-lined chromospherically active RS CVn-type star 29 Draconis (HD 160538). From the high resolution spectra obtained on the Nordic Optical Telescope, abundances of 22 chemical elements, including the key elements such as 12 C, 13 C, N and O, were investigated. The differential line analysis with the MARCS model atmospheres gives T eff = 4720 K, log g = 2:5, [Fe/H] = -0:20, [C/Fe] = -0:14, [N/Fe] = 0:08, [O/Fe] = -0:04, C/N = 2:40, 12 C/ 13 C = 16. The low value of the 12 C/ 13 C ratio gives a hint that extra mixing processes in low-mass chromospherically active stars may start earlier than the theory of stellar evolution predicts.

The possibility of applying photometry from the 2MASS J, H, K s , MegaCam u, g and IPHAS r, i, Hα surveys for determining the distance to the dark cloud LDN1525 (TGU 1192) in the direction of the Aur OB1 association is investigated using the red clump giants. The main dust cloud, probably related to the emission nebulae Sh 2-232, Sh 2-233, Sh 2-235, the molecular cloud and the association Aur OB2, is found to be located at a distance of 1.3 kpc from the Sun. The nebula Sh 2-231 can be an object of the Perseus arm. The maximum extinction A V found in the cloud is close to 6 mag.

The contamination in the Gaia BP and RP spectra, caused by the LSF smearing, is a serious obstacle for the classification of stars since the contamination values at different wavelengths depend on temperatures, gravities, metallicities and interstellar reddenings of stars, and these parameters are unknown before the classification. This makes impossible to apply traditional methods for photometric classification of stars based on color indices or interstellar reddening-free Q-parameters. For determining contamination for the stars of ‘normal’ spectral sequence we propose the method of ‘color equations’, well known in stellar photometry. The equations connecting the decontamination correction at a chosen wavelength with the observed ‘color indices’ are derived. These equations make possible to determine decontamination corrections for unreddened stars with an accuracy of 0.01-0.02 mag in the wavelength range of 400-1000 nm. The equations are different for M-type stars which can be separated from stars of earlier spectral classes using the contaminated RP spectra and treated separately. The equations are valid not only for unreddened stars but also for stars affected by interstellar extinction up to A V = 3 mag. At shorter wavelengths (350-400 nm) the contamination is much larger and can be determined with lower accuracy.

We present the results of CCD photometry in the seven-color Vilnius system for 1549 stars down to V ∼16 mag in a 1.5 square degree field around the cluster King 7, at the Perseus and Camelopardalis border. Using photometric parameters, two-dimensional spectral types, interstellar extinctions and distances for most of the stars are determined.

The spectroscopic orbit of a high proper motion star, BD+20 5152, is calculated from 34 CORAVEL-type radial velocity measurements. The star has a slightly eccentric orbit with a period of 5.70613 d, half-amplitude of 47.7 km/s and eccentricity of 0.049. The center-of-mass velocity of the system is -24.3 km/s. BD+20 5152 seems to be a triple system consisting of a G8 dwarf as a primary component and of two K6-M0 dwarfs as secondary and tertiary components. This model is based on the analysis of its UBVRI and JHK magnitudes. According to the SuperWASP photometry, spots on the surface of the primary are suspected. The excessive brightness in the Galex FUV and NUV magnitudes and a non-zero eccentricity suggest the age of this system to be less than 1 Gyr.

A project for astrometric and photometric observations of asteroids at the Baldone Observatory is described. One of the most important results of the project is the discovery of 2008 OS9, a 600 meter asteroid of the NEO Apollo group. The results of its astrometric and photometric observations at the Molėtai and Baldone observatories are presented. From the brightness variation with the 0.27 mag amplitude, a rotation period of 8.430 ± 0.005 h is determined. Close approaches of the asteroid to Earth and Venus during the next millenium are predicted. The mean values of secular changes in the semi-major axis, eccentricity and inclination are computed with and without the Yarkovsky and YORP effects. A negative value of the difference between the value of semi-major axis computed with the Yarkovsky and YORP effects and without them, da/dt, may indicate retrograde rotation of the asteroid.

A translation of a section from the 1665 Astronomia Reformata of G. B. Riccioli discussing the appearance of the disk of Jupiter during the years 1630-1664; changes in the Jovian cloud belts as recorded by a variety of observers are a major feature of Riccioli’s discussion.