HIGH-RESOLUTION OBSERVATIONS OF MOLECULAR GAS IN THE EARLY-TYPE DWARF GALAXY NGC 404

Abstract

We present Berkeley–Illinois–Maryland Association CO (1–0) observations of the nearby dwarf elliptical galaxy NGC 404. The detected CO emission is concentrated in a small feature, slightly larger than the beam size, at the center of the optical galaxy. For an assumed CO-to-H2 conversion factor of 2.3 (K km s−1)−1, the molecular gas mass is 9.0 M⊙. The velocity field suggests rotation, with a position angle ~90° different from previous single-dish observations. Both position angles are different from that of the extended H i distribution detected by del Rio et al. The lack of agreement between the postion angle of the CO velocity field and other position angles suggests an external origin for the central molecular gas clump in NGC 404.