Inner Polar Rings and Disks: Observed Properties

TL;DR

This paper compiles and analyzes observational data on inner polar rings and disks across 47 galaxies, revealing their properties, distribution, and possible formation mechanisms related to galactic interactions.

Contribution

It provides a comprehensive statistical overview of inner polar structures, highlighting their sizes, occurrence in different galaxy types, and relation to galactic bars and interactions.

Findings

Polar structures mostly do not exceed 1.5 kpc in radius.

Polar structures are equally common in barred and unbarred galaxies.

Most galaxies with polar structures show signs of recent interactions.

Abstract

A list of galaxies with inner regions revealing polar (or strongly inclined to the main galactic plane) disks and rings is compiled from the literature data. The list contains 47 galaxies of all morphological types, from E to Irr. We consider the statistics of the parameters of polar structures known from observations. The radii of the majority of them do not exceed 1.5 kpc. The polar structures are equally common in barred and unbarred galaxies. At the same time, if a galaxy has a bar (or a triaxial bulge), this leads to the polar disk stabilization - its axis of rotation usually coincides with the major axis of the bar. More than two thirds of all considered galaxies reveal one or another sign of recent interaction or merging. This fact indicates a direct relation between the external environment and the presence of an inner polar structure.