6-meter telescope observations of three dwarf spheroidal galaxies with very low surface brightness

Dwarf spheroidal galaxies (dSphs) are mostly investigated in the Local Group. DSphs are difficult targets for observations because of their small size and very low surface brightness. Here we measure spectroscopic and photometric parameters of three candidates for isolated dSphs, KKH65=BTS23, KK180, and KK227, outside the Local Group. The galaxies are found to be of low metallicity and low velocity dispersion. They are among the lowest surface brightness objects in the Local Universe. According to the measured radial velocities, metallicities, and structural and photometric parameters, KKH65 and KK227 are representatives of the ultra-diffuse quenched galaxies. KKH65 and KK227 belong to the outer parts of the groups NGC3414 and NGC5371, respectively. KK180 is located in the Virgo cluster infall region.Comment: 4 pages, 3 figures, 3 tables, 3 Appendices with 5 figures and 3 table

Simulation of population’s reproductive behaviour patterns within an agent-oriented regional model

The study focuses on the research on how the unevenness of demographic transition affects the social and demographic characteristics and their dynamics of a region’s population. The research was conducted by means of computerized experiments (simulations) set within an original agent-oriented model. The study features the structure of the model represented by an artificial society, with its members (agents) being attributed their personal characteristics in such a way that they would imitate the gender and age of the region’s population. The agents are divided into two groups which differ in their reproductive strategy. Agents from Group 1 adhere to the traditional strategy characterized by a high birth rate, while the agents from Group 2 follow the modern strategy resulting in a markedly low birth rate. With the application of probabilistic mechanisms, the natural birth-death processes are imitated within the model. The extinction of agents occurs in accordance with the death rates adjusted for age and gender but remaining the same for the whole population. In the model, the appearance of new agents (birth of children) results from the choice made by reproductive-aged female agents, and their choice is influenced by the subjective traits determined by their group. The age and social structure of the regional population are generally formed as a result of the aggregation of particular agents’ activity. The model has been applied in a range of experiments on forecasting the number and structure of the population in an assumed region. The results showed that despite the apparent simplification of the reality, the developed agent-oriented model correctly represents both the initial condition of the regional population including the gender, age and social structure and the dynamics of the population’s basic characteristics.The research has been supported by the Russian Science Foundation (Project № 14-18-01968)