Eclipsing Variables in New Name-Lists of Variable Stars

Три недавних Списка обозначений переменных звезд в системе ОКПЗ были в значительной степени посвящены переменным звездам шаровых скоплений. Несмотря на то, что затменные переменные обычно не рассматриваются как характерное население шаровых скоплений, их в этих Списках оказалось немало. Следующий Список, публикация которого предполагается в 2023 г., также будет преимущественно посвящен переменным звездам шаровых скоплений, причем в списке включаемых скоплений преобладают скопления из созвездия Стрельца. В плотных полях этого созвездия в области некоторых шаровых скоплений члены скопления оказываются в меньшинстве, и многие переменные звезды не включены в специализированный каталог переменных звезд в шаровых скоплениях. На примере скопления Terzan 10 мы рассмотрим следствия для каталогизации затменных переменных звезд.Three recent Name-lists of variable stars in the GCVS system were largely devoted to variable stars in globular clusters. Though eclipsing variables are usually not considered as population typical of globular clusters, there is quite a number of them in these Name-lists. The next Name-list, scheduled for publication in 2023, will also predominantly deal with globular-cluster variable stars, and the list of clusters selected for this Name-list is dominated with clusters from Sagittarius. In the regions of some globular clusters in crowded Sagittarius fields, cluster members are a minority, so that many variable stars do not enter the special Catalog of variable stars in globular clusters. Using the cluster Terzan 10 as an example, we consider consequences for compiling catalogs of eclipsing variable stars.Автор признателен Е. Н. Пастуховой, Е. В. Казаровец и Н. Н. Киреевой за участие в работе по включению в ОКПЗ переменных звезд шаровых скоплений

The plate archive of the Sternberg Astronomical Institute

Program available at: http://www.imcce.fr/hosted_sites/naroo/program.htmlInternational audienceThe photographic observations in the Sternberg Astronomical Institute started in 1895. Observations were made with sept telescopes in Moscou and Crimea. In total, until 2004, almost 60 000 photographic plates have been accumulated. Most of them have been made to study variable stars and galaxies. Only the 9 000 from 60 000 photographic plates were made to determine the coordinates of Mars, Venus and selected asteroids. These photographic plates are processed. Some of obtained results are published. These 9 000 plates may be the subject of a new processing with the new star catalogs after they are scanned. This work can be undertaken if there is interest in new astrometric data with a modest accuracy for Mars, Venus, and selected asteroids. This year, work has begun to search for objects of the solar system in other 51 000 photographic plates made to study variable stars and galaxies. The main interest was in finding the planets with natural satellites. For given moments of exposure and the coordinates of the field center using a relevant software, we determine the presence of planets on each plate. A significant problem is that most of plates are identified only by the name of the galaxy or star. Our problem is also that only for 25 000 plates we have the moments and the coordinates recorded in the files. For the remaining 26 000 plates these data are still noted on paper. Of the 25 000 examined plates only on 340 of them the planets were found. We should also identify and write to file such data for 26,000 plates to search for planets with our software. For half of the 51 000 plates expected astrometric accuracy is of about 0.2 arcseconds and for other plates the accuracy is not better than 1 arcsecond of arc. About 1 700 photographic plates were scanned for photometric purposes. However astrometric accuracy of the scan does not match the possible accuracy of photographic plates

The Unique Frequency Spectrum of the Blazhko RRc Star LS Her

The Blazhko effect in RR Lyrae stars is still poorly understood theoretically. Stars with multiple Blazhko periods or in which the Blazhko effect itself varies are particularly challenging. This study investigates the Blazhko effect in the RRc star LS Her. Detailed VRI CCD photometry has been performed on 63 nights during six months. LS Her is confirmed to have a Blazhko period of 12.75+/-0.02 days. However, where normally the side frequencies of the Blazhko triplet are expected, an equidistant group of three frequencies is found on both sides of the main pulsation frequency. As a consequence the period and amplitude of the Blazhko effect itself vary in a cycle of 109+/-4 days. LS Her is a unique object turning out to be very important in the verification of the theories for the Blazhko effect.Comment: Accepted for publication in MNRA

A Library of Integrated Spectra of Galactic Globular Clusters

We present a new library of integrated spectra of 40 Galactic globular clusters, obtained with the Blanco 4-m telescope and the R-C spectrograph at the Cerro Tololo Interamerican Observatory. The spectra cover the range ~ 3350 -- 6430 A with ~ 3.1 A (FWHM) resolution. The spectroscopic observations and data reduction were designed to integrate the full projected area within the cluster core radii in order to properly sample the light from stars in all relevant evolutionary stages. The S/N values of the flux-calibrated spectra range from 50 to 240/A at 4000 A and from 125 to 500/A at 5000 A. The selected targets span a wide range of cluster parameters, including metallicity, horizontal-branch morphology, Galactic coordinates, Galactocentric distance, and concentration. The total sample is thus fairly representative of the entire Galactic globular cluster population and should be valuable for comparison with similar integrated spectra of unresolved stellar populations in remote systems. For most of the library clusters, our spectra can be coupled with deep color-magnitude diagrams and reliable metal abundances from the literature to enable the calibration of stellar population synthesis models. In this paper we present a detailed account of the observations and data reduction. The spectral library is publicly available in electronic format from the National Optical Astronomical Observatory website.Comment: 39 Pages, including 2 tables and 15 Figures. To appear in the Astrophysical Journal, Supplement Serie

Eclipsing variable stars in the Moscow program for scanning the astronomical plate stacks

Рассматриваются результаты полуавтоматического поиска затменных переменных звезд по сканам московской коллекции астронегативов и особенности распределения обнаруженных затменных переменных по периодам.We consider the results of our semi-automated search for eclipsing variables using scans of the Moscow astronomical plate stacks and characteristics of the eclipsing variables’ distribution over periods