The dusty disk of the early-type galaxy ngc 3656

Abstract

SHARC II 350 µm continuum and archival HST J −H band maps are presented of NGC 3656, the brightest of our sample of six elliptical galaxies for which resolved CO gas disks have recently been detected with 7′′ -spatial-resolution, interferometry mapping. These gas disks confirm the conclusions of earlier results showing optical dust lanes and unresolved CO that implied the common existence of molecular gas in ellipticals and the disk-like structure of this gas. The presented SHARC II mapping results provide the best-to-date resolved FIR-submm extent of NGC 3656 and of any elliptical galaxy >40 Mpc, showing that dust of 29 K exists out to at least ∼1.8 kpc in this galaxy. These new data are used in conjunction with the archival HST maps and other published data to determine dust properties and associations with galactic structures, including dominant heating sources such as star-formation or diffuse-stellar radiation.