Properties of disks and spiral arms along the Hubble sequence

National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, P.R. China

Corresponding author: majun@vega.bac.pku.edu.cn

Received: 6 December 2001
Accepted: 13 March 2002

Abstract

This paper presents some new statistical correlations between the properties of disks and of spiral arms with some physical properties of galaxies. Our results show that the thickness of spiral disks tends to diminish along the Hubble sequence in the sense that disks of Sc galaxies are 40% thinner than disks of Sab-Sb galaxies. Moreover, the thinner disks tend also to be bluer. We also find that there exists a correlation between HI linewidths and arm pattern within each Hubble type, which suggests that the arm shape is partially determined by the mass of a galaxy. Total mass luminosity ratios and total mass surface densities also have correlations with pitch angles i.e., for disks with lower surface densities and lower total mass luminosity ratios, the pitch angles tend to be greater.