Amplitude and Shape of Spiral Arms in K’

Abstract

Full understanding of the dynamics of spiral galaxies requires accurate models of their potentials including non-axisymmetric perturbations e.g. spiral patterns. Although a detailed kinematic mapping of the Population II stars in their disks would provide this information, it is not currently feasible. An alternative is to use cause kinematic data to derive the general axisymmetric potential and surface photometry to deduce the density perturbations in the disk at higher spacial frequencies. Light at wavelengths blue of 1μm is strongly effected by dust extinction and population variations whereas these problems are much less serious in near-infrared bands like K’ at 2.1μm (Rix and Rieke, 1993). This makes it possible to estimate surface density variations in the old stellar disk population of galaxies from K’ maps and thereby study their dynamics (Block et al., 1994).