Progress in Understanding the Nature of SS433

SS433 is the first example of a microquasar discovered in the Galaxy. It is a natural laboratory for studies of extraordinarily interesting physical processes that are very important for the relativistic astrophysics, cosmic gas dynamics and theory of evolution of stars. The object has been studied for over 40 years in the optical, X-ray and radio bands. By now, it is generally accepted that SS433 is a massive eclipsing X-ray binary in an advanced stage of evolution in the supercritical regime of accretion on the relativistic object. Intensive spectral and photometric observations of SS433 at the Caucasian Mountain Observatory of the P. K. Sternberg Astronomical Institute of M. V. Lomonosov Moscow State University made it possible to find the ellipticity of the SS433 orbit and to discover an increase in the system’s orbital period. These results shed light on a number of unresolved issues related to SS433. In particular, a refined estimate of the mass ratio MxMv>0.8 was obtained (Mx and Mv are the masses of the relativistic object and optical star). Based on these estimates, the relativistic object in the SS433 system is the black hole; its mass is >8M⊙. The ellipticity of the orbit is consistent with the “slaved” accretion disc model. The results obtained made it possible to understand why SS433 evolves as the semi-detached binary instead of the common envelope system.

Alexander Nikolaevich Deutsch on the occasion of his 120th anniversary

The year 2019 is the year of the 120th anniversary of Alexander Nikolaevich Deutsch (1899-1986), the Pulkovo astronomer, doctor of physical and mathematical Sciences, Professor, who for many years was the head of the Department of photographic astrometry and stellar astronomy of the Main Astronomical Observatory, Russian Academy of Sciences (GAO RAS), the supervisor and teacher of several generations of Pulkovo astronomers and employees of other observatories. This article presents the scientific and social activities of A.N. Deutsch. Archived data is provided that evidence his participation, along with other Pulkovo employees, in the salvation of the property and scientific Fund of the Pulkovo Observatory during the great Patriotic war, as well as in the work to restore the Observatory. The article is based on the presentation given to and approved by the conference "Astrometry: yesterday, today, tomorrow" (Sternberg Astronomical Institute, Moscow State University, October 14-16, 2019).

Creation of a new global geomorphological catalog of Mercury’s craters based on the latest MESSENGER data

<p>Catalogs of impact craters – not only a layers of objects in GIS but complete databases containing the morphometric and geomorphological characteristics – can help to solve such fundamental problems as the estimation of parameters of populations of impactors that collided with the surface of the planet throughout its history, as well as to clarify the processes of crater formation in the Solar System.</p><p>Currently, there are few global catalogues of Mercury that includes big craters only. For example: 1) global digital GIS-catalogue of Mercury’s craters created by the Braun University, USA. It is based on modern data gathered by MESSENGER and, along with approximately 9000 objects; it includes coordinates and diameters of large craters (> 20 km), exclusively. At the same time, it doesn’t contain any geomorphological information; 2) the other source is a geomorphological catalogue that was composed by Sternberg Astronomical Institute (SAI), which, while containing geomorphological information, was created in accordance to data of Mariner 10 and was presented as a text in a table. The SAI’s catalogue includes craters with a size of 10 km and larger. </p><p>Creation of a new global catalog of Mercury’s craters based on the latest MESSENGER data is a comprehensive work. The catalog will consist of two subdirectories: 1) the geomorphological catalog of craters with a size of 10 km and larger; 2) the morphometric catalog of craters with a size less than 10 km. We use MESSENGER MDIS global mosaic of Mercury with resolution ~166 m/pixel and several MESSENGER DEMs – the first global Mercury DEM with resolution 665 m/pixel and four DEMs on Mercury quadrants with resolution ~222 m/pixel (which will be used for formation of a database of craters with diameters less than 10 km).</p><p>In addition to the required elements of any catalog (coordinates of craters and their diameters), we will be able to add full geomorphological description of craters, reduced to code designations (to simplify the implementation of the catalog in the GIS) and morphometric characteristics. For instance: 1) the diameter of the interior feature (flat floor, central peak, or inner ring); 2) depth and relative depth of each crater; 3) max and min slopes; 4) the average level of inclination of the external; 5) internal slopes of crater; 6) the ratio of volume of the crater rim to the volume of the bowl. The most of listed parameters can be calculated both for craters and for the surrounding surface.</p><p>By using this catalog, we will be able to quickly get statistics and create thematic maps, for example, maps of crater density on regions of interest.</p><p>This research was supported by Russian Foundation for Basic Research (RFBR), project No 20-35-70019.</p>

Observational Facilities of Sternberg Astronomical Institute for Ground-Based Photometric Study of Newly Identified GAIA Objects, — CV-candidates.

The extended observational program for study of cataclysmic variables is realized in Sternberg Astronomical Institute during the last years. A few telescopes of Crimean Observational Station equipped with a different devices, — UBV photometer and two CCD camera, are used for observations. Among the close binary systems (CBS), cataclysmic variables are the most interesting objects because of the outburst activity and variety of their observational features. They could serve a good laboratory for study of physical processes in CBS. GAIA provides astronomers with a new ample opportunity for investigation of cataclysmic variables. Though the relative faintness of detected objects it is still possible to carry out a high accuracy ground-based observations with our equipment. Obtained ground-based data permit us to confirm classification of detected CV-candidates, to determine the physical characteristics with a sample of new cods and improve the current understanding of their nature.

Study of Photometric Variability of Selected SU UMa Dwarf Novae

In this work we present time-resolved photometry of several poorly-studied dwarf novae during recent superoutbursts. Observations were made with a CCD, mounted on 50- and 60-cm telescopes of the Sternberg Astronomical Institute in Crimea in April - May and October 2012 and June - July 2013. Superhumps were detected in light curves of all the dwarf novae. The amplitudes and periods of detected light variations were calculated. Superhumps evolution was also followed up for all systems and classification is improved.