On the Formation of Spiral Arms in Dwarf Galaxiesстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 26 января 2022 г.
Аннотация:Spiral structure (both flocculent and Grand Design types) is very rarely observed in dwarf galaxiesbecause the formation of spiral arms requires special conditions. In this work we analyze the sample of about 40 dS-galaxies found by scanning by eye the images of late-type galaxies with m_B<15 and M_B>-18 and andphotometric diameter D_25<12 kpc. We found that apart from the lower average gas (HI) fraction the otherproperties of dS-galaxies including the presence of a bar and the isolation index do not differ much from thosefor dwarf Irr or Sm-types of similar luminosity and rotation velocity (or specific angular momentum).Thereare practically no dS-galaxies with rotation velocity below 50–60 km/s. To check the conditions of forma-tion of spiral structure in dwarf galaxies we carried out a series of N-body/hydrodynamic simulations of low-mass stellar-gaseous discy galaxies by varying the model kinematic parameters of discs, their initial thickness,relative masses and scale lengths of stellar and gaseous disc components, and stellar-to-dark halo masses. Wecame to conclusion that the gravitational mechanism of spiral structure formation is effective only for thinstellar discs, which are non-typical for dwarf galaxies, and for not too slowly rotating galaxies. Therefore, onlya small fraction of dwarf galaxies with stellar/gaseous discs have spiral or ring structures. The thicker stellardisc, the more gas is required for the spiral structure to form. The reduced gas content in many dS-galaxiescompared to non-spiral ones may be a result of more efficient star formation due to a higher volume gas den-sity thank to the thinner stellar/gaseous discs.