Band 19, Heft 1-2

Using photometric data of infrared surveys, young stellar object (YSO) status is verified for 141 objects selected in our previous papers in the Cassiopeia and Camelopardalis segment of the Milky Way bounded by Galactic coordinates (l, b) = (132-158°, ±12°). The area includes the known star- forming regions in the emission nebulae W3, W4 and W5 and the massive YSO AFGL490. Spectral energy distribution (SED) curves between 700 nm and 160 μm, constructed from the GSC 2, 2MASS, IRAS, MSX, Spitzer and AKARI data, are used to estimate the evolutionary stages of these stars. We confirm the YSO status for most of the objects. If all of the investigated objects were YSOs, 45% of them should belong to Class I, 41% to class II and 14% to Class III. However, SEDs of some of these objects can be affected by nearby extended infrared sources, like compact H II regions, infrared clusters or dusty galaxies.

The results of CCD photometry in the seven-color Vilnius system of 3058 stars down to V ~ 18.0 mag in a 1.5 square degree field around the cluster NGC 752 are presented. For most of the stars brighter than V = 17.0 mag, photometric spectral and luminosity classes are determined. The catalog of 1174 stars down to V = 15.5 mag is given in the paper. The entire catalog will be available at the CDS Simbad database. The color-magnitude diagram indicates an extension of the cluster’s main sequence down to 5 mag below the turnoff point.

CCD photometry in the eight-color Vilnius + I system for 7250 stars down to I =19.6 mag has been obtained in the 20′ × 26′ field of the open cluster IC 361 in Camelopardalis. The catalog of 1420 stars down to V ~ 18.5 mag is presented. It contains the coordinates, V magnitudes and seven color indices, quantitative photometric spectral types, absolute magnitudes and distances. The interstellar extinction is found to be non-uniform across the field, with the values of A V in the range 1.9 to 2.4 mag. The distribution of distance moduli of individual stars shows that the cluster is located as far as, or just beyond, the Perseus spiral arm.

Photospheric parameters and chemical composition are determined for the single-lined chromospherically active RS CVn-type star λ And (HD 222107). From the high resolution spectra obtained on the Nordic Optical Telescope, abundances of 22 chemical elements and isotopes, including such key elements as 12 C, 13 C, N and O, were investigated. The differential line analysis with the MARCS model atmospheres gives T eff = 4830 K, log g = 2.8, [Fe/H] = -0.53, [C/Fe] = 0.09, [N/Fe] = 0.35, [O/Fe] = 0.45, C/N = 2.21, 12 C/ 13 C = 14. The 12 C/ 13 C ratio for a star of the RS CVn-type is determined for the first time, and its low value gives a hint that extra-mixing processes may start acting in low-mass chromospherically active stars below the bump of the luminosity function of red giants.

We present a model of chemical and spectrophotometric evolution of disk galaxies based on a stochastic self-propagating star formation scenario. The model incorporates galaxy formation through the process of accretion, chemical and photometric evolution treatment, based on simple stellar populations (SSP), and parameterized gas dynamics inside the model. The model reproduces observational data of the late-type spiral galaxy M33 reasonably well. Promising test results prove the applicability of the model and the adequate accuracy for the interpretation of disk galaxy properties.

Sets of orthogonal basis functions over circular areas - pupils in optical applications - are known in the literature for the full circle (Zernike or Jacobi polynomials) and the annulus. Here, an orthogonal set is proposed if the area is two non-overlapping circles of equal size. The geometric master parameter is the ratio of the pupil radii over the distance between both circles. Increasingly higher order aberrations - as defined for a virtual larger pupil in which both pupils are embedded - are fed into a Gram-Schmidt orthogonalization to distill one unique set of basis functions. The key effort is to work out the overlap integrals between a full set of primitive basis functions of hyperspherical type centered at the mid-point between both pupils. Constructed from the same primitive basis, the orthogonal Karhunen-Loève modes of spatially filtered Kolmogorov phase screens are computed for this shape of mask. Matrix elements of the covariance matrix - an established intra-circle and a special inter-circle category - are worked out in wavenumber space.

The previously published factor, which scales the matrix elements of the eigenvalue equation as a finite outer scale of the von-Kármán model is switched on, is corrected.