ABSTRACT

We are investigating the properties of gas in the elliptical (E) components of E+S pairs. This is being done both by determining the physical conditions of the gas and by spectral synthesis of the underlying stellar population. A major goal is to determine whether cross fueling occurs in such pairs. We present data for AM 0327-285 which is an E+S pair showing signs of tidal interaction between the E and S components. We present evidence for gas transfer from the spiral to the elliptical component.

INTRODUCTION

Paired galaxies as nonequilibrium systems provide a unique chance to study the physics of interaction, galaxy evolution, and the effects of environment on galaxies. If environment at the formation epoch plays a major role on morphology, components of binary galaxies might be expected to show morphological concordance. More recently the formation of elliptical galaxies has been revisited in the light of new observational evidence for fine structure suggesting a “nurture” origin. Therefore, the existence of a large number of true mixed pairs (E+S) (about 25% of an unbiased binary sample are mixed pairs [Sulentic 1990]) raises interesting questions.

We are studying the properties of mixed pairs using low resolution spectroscopy and stellar population synthesis. Such pairs provide a unique insight because they involve one gas rich galaxy in the presence of a relatively clean perturber.