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Seminar (03.04.2024, 15:00)

Опубликовано: 29/03/2024

1.  Authors: Kiselev Nikolai, Institute of Astronomy of the Russian Academy of Sciences, 
G. Dyachenko (Unior Academy of Sciences “EXPLORER”), N. Karpov (INASAN), K. Antonyuk (CrAO RAS)

Title: On the longitudinal dependence of the polarization of Jupiter’s satellites Io and Ganymede

Polarimetric observations of Jupiter’s moons Io and Ganymede were carried out in a narrow range of phase angles of (10 – 12)° at the 2.6m and 1.25m telescopes of CrAO and the 2m telescope of the Peak Terskol Observatory in 2019 – 2024. This made it possible to find changes in the degree of polarization at the surface of the satellites – the longitudinal (orbital) effects, without taking into account the phase dependences of the polarization of the satellites. We find that the amplitude of Ganymede’s orbital polarization changes at a phase angle of about 11° is close to that found by Dollfus (1975) of about 0.2%. A comparison of the new parameters of the longitudinal polarization of Io with the data obtained by Zellner and Gradie in 1975 showed a noticeable difference. It can be explained by a “long time” change in volcanic activity on the surface of Io.

2.  Authors: Zolotarev Roman, Institute of Astronomy of the Russian Academy of Sciences, 

Title:Comparison of population models of near-Earth objects on the example of the problem of the characteristic lifetime of the near-Earth object population

The report will discuss the results of numerical modeling of the dynamic evolution of the population of asteroids approaching Earth (Near-Earth Objects, NEOs) using different sets of initial orbital parameters, obtained with the help of the software complexes NEOPOP and NEOMOD, as well as samples from the Minor Planet Center’s database. The main goal of the modeling is to find the characteristic lifetime of the NEO population, which, within the context of this report, will be understood as the median lifetime of the NEO population – the time it takes for the current population of NEOs to decrease by half. This task is important for refining the mechanisms of replenishing the NEO population

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