Parameters of galactic disks at optical and NIR wavelengths

TL;DR

This study analyzes the structural and photometric properties of 404 galactic disks across different galaxy types, revealing smooth variations along the Hubble sequence and examining the influence of dust and inclination.

Contribution

It provides a comprehensive analysis of galactic disk parameters across various galaxy types, highlighting smooth transitions and the effects of dust and inclination.

Findings

Central surface brightness and disk scale length vary smoothly along the Hubble sequence.

Disks in S0 galaxies are more homogeneous than in spiral galaxies.

Dust concentrated in spiral arms does not affect scale length ratios.

Abstract

We have analyzed the radial scales, central surface brightnesses, and colors of 404 disks of various types of galaxies. The central surface brightness mu0 and linear disk scale length h vary smoothly along the Hubble sequence of galaxies within a rather narrow interval. The disks of relatively early type galaxies display higher central surface brightnesses in K, higher central surface densities, smaller sizes (relative to the diameter of the galaxy), redder integrated and central colors. The color gradient normalized to the radius of the galaxy and the blue central surface brightness mu0_{0,i}(B) of the disk, are both independent of the galaxy type. The radial disk scales in different photometric bands differ less in early-type than in late-type galaxies. The ratio of linear disk scales measured in different photometric bands increases with the isophote ellipticity e of the disk (the inclination of the galaxy); however, the range of the ratio values for each e value exceeds the range of variations of scale lengths ratio over e. The disks in S0 galaxies have more homogeneous parameters than those in spiral galaxies. However, no sharp boundary in the properties of disks in lenticular, spiral, and irregular galaxies has been found; all parameters vary smoothly along the Hubble sequence. A correlation between the central disk surface brightness and the total luminosity of the galaxy is observed. We also consider the influence of dust on the photometric parameters of the disks. We show that the dust concentrated in dust lines towards the spiral arms and bars does not influence to the scale lengths ratio.