We have proposed a generalized King’s model for the observed density of stars in globular cluster... more We have proposed a generalized King’s model for the observed density of stars in globular clusters (GC). Using two methods of minimizing the functional, composed in the form of the square of the difference between the theoretical and observed density values, we obtained the behavior of the degree of concentration for 26 GC. We have taken the observational data for these clusters from the work of Miocchi et al. (2013), which is a combination of ground-based and space-based observations. The minimized functional depends on three free parameters and one of them clearly characterizes the concentration of stars towards the center of the cluster. The two research methods used here give almost the same results with reasonably good accuracy. In contrast to the work of Nuritdinov et al. (2021), the χ 2 method is used to determine the degree of concentration. In addition, we analyzed data from de Boer et al. (2019). However, these data do not contain information for the central regions of the...
Kinematic data of 117 open clusters younger than 100 million years with proper motions reduced to... more Kinematic data of 117 open clusters younger than 100 million years with proper motions reduced to the HIPPARCOS reference system are presented. (1 data file).
The nearest neighbor distribution Chandrasekhar (1943) is generalized to fractal stellar systems.... more The nearest neighbor distribution Chandrasekhar (1943) is generalized to fractal stellar systems.For such systems an asymptotic distribution of the magnitude of large random forces and a formula for the effective mean interparticle spacing are derived. It is shown that in the case of a power-law distribution of conditional density the derived asymptotic fully agrees with the results obtained in terms of a general approach. It is concluded that large random forces in a fractal stellar medium are due entirely to the nearest neighbors (clumps) located inside the sphere of the effective radius determined from the generalized Holtsmark distribution.
ABSTRACT The results of long‐term observational program of classical cepheid investigations carri... more ABSTRACT The results of long‐term observational program of classical cepheid investigations carried out in Moscow from 1980th, are presented. The data base includes more than 75000 UBVRI photoelectric and CCD brightness measurements for more than 650 galactic Cepheids, and approximately 10000 precise measurements of radial velocities for 165 Northern Cepheids. Classical Cepheids as stars with the most reliable distance scale play an important role in all investigations of the structure and dynamics of the galactic disk. Being observed on 100 year time interval, more than 90% of cepheids show systematic period changes. New observations are necessary to improve cepheid period—luminosity relations by taking into account the difference in their evolutionary stages and misidentification of pulsation modes.
Monthly Notices of the Royal Astronomical Society, 2015
ABSTRACT Stellar population and the interstellar gas-dust medium in the vicinity of the open star... more ABSTRACT Stellar population and the interstellar gas-dust medium in the vicinity of the open star cluster vdB 130 are analysed using optical observations taken with the 6-m telescope of the SAO RAS and the 125-cm telescope of the SAI MSU along with the data of Spitzer and Herschel. Based on proper motions and BV and JHKs 2MASS photometric data, we select additional 36 stars as probable cluster members. Some stars in vdB 130 are classified as B stars. Our estimates of minimum colour excess, apparent distance modulus and the distance are consistent with young age (from 5 to 10 Myrs) of the cluster vdB 130. We suppose the large deviations from the conventional extinction law in the cluster direction, with $R_V$ ~ 4 - 5. The cluster vdB 130 appears to be physically related to the supershell around Cyg OB1, a cometary CO cloud, ionized gas, and regions of infrared emission. There are a few regions of bright mid-infrared emission in the vicinity of vdB 130. The largest of them is also visible on H-alpha and [SII] emission maps. We suggest that the infrared blobs that coincide in projection with the head of the molecular cloud are HII regions, excited by the cluster B-stars. Some signatures of a shock front are identified between these IR-bright regions.
We have proposed a generalized King’s model for the observed density of stars in globular cluster... more We have proposed a generalized King’s model for the observed density of stars in globular clusters (GC). Using two methods of minimizing the functional, composed in the form of the square of the difference between the theoretical and observed density values, we obtained the behavior of the degree of concentration for 26 GC. We have taken the observational data for these clusters from the work of Miocchi et al. (2013), which is a combination of ground-based and space-based observations. The minimized functional depends on three free parameters and one of them clearly characterizes the concentration of stars towards the center of the cluster. The two research methods used here give almost the same results with reasonably good accuracy. In contrast to the work of Nuritdinov et al. (2021), the χ 2 method is used to determine the degree of concentration. In addition, we analyzed data from de Boer et al. (2019). However, these data do not contain information for the central regions of the...
Kinematic data of 117 open clusters younger than 100 million years with proper motions reduced to... more Kinematic data of 117 open clusters younger than 100 million years with proper motions reduced to the HIPPARCOS reference system are presented. (1 data file).
The nearest neighbor distribution Chandrasekhar (1943) is generalized to fractal stellar systems.... more The nearest neighbor distribution Chandrasekhar (1943) is generalized to fractal stellar systems.For such systems an asymptotic distribution of the magnitude of large random forces and a formula for the effective mean interparticle spacing are derived. It is shown that in the case of a power-law distribution of conditional density the derived asymptotic fully agrees with the results obtained in terms of a general approach. It is concluded that large random forces in a fractal stellar medium are due entirely to the nearest neighbors (clumps) located inside the sphere of the effective radius determined from the generalized Holtsmark distribution.
ABSTRACT The results of long‐term observational program of classical cepheid investigations carri... more ABSTRACT The results of long‐term observational program of classical cepheid investigations carried out in Moscow from 1980th, are presented. The data base includes more than 75000 UBVRI photoelectric and CCD brightness measurements for more than 650 galactic Cepheids, and approximately 10000 precise measurements of radial velocities for 165 Northern Cepheids. Classical Cepheids as stars with the most reliable distance scale play an important role in all investigations of the structure and dynamics of the galactic disk. Being observed on 100 year time interval, more than 90% of cepheids show systematic period changes. New observations are necessary to improve cepheid period—luminosity relations by taking into account the difference in their evolutionary stages and misidentification of pulsation modes.
Monthly Notices of the Royal Astronomical Society, 2015
ABSTRACT Stellar population and the interstellar gas-dust medium in the vicinity of the open star... more ABSTRACT Stellar population and the interstellar gas-dust medium in the vicinity of the open star cluster vdB 130 are analysed using optical observations taken with the 6-m telescope of the SAO RAS and the 125-cm telescope of the SAI MSU along with the data of Spitzer and Herschel. Based on proper motions and BV and JHKs 2MASS photometric data, we select additional 36 stars as probable cluster members. Some stars in vdB 130 are classified as B stars. Our estimates of minimum colour excess, apparent distance modulus and the distance are consistent with young age (from 5 to 10 Myrs) of the cluster vdB 130. We suppose the large deviations from the conventional extinction law in the cluster direction, with $R_V$ ~ 4 - 5. The cluster vdB 130 appears to be physically related to the supershell around Cyg OB1, a cometary CO cloud, ionized gas, and regions of infrared emission. There are a few regions of bright mid-infrared emission in the vicinity of vdB 130. The largest of them is also visible on H-alpha and [SII] emission maps. We suggest that the infrared blobs that coincide in projection with the head of the molecular cloud are HII regions, excited by the cluster B-stars. Some signatures of a shock front are identified between these IR-bright regions.
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Papers by A. Rastorguev