CO J = 10 observations of the Circinus galaxy using the Mopra 22-m radio-telescope

Introduction

The Circinus galaxy is a member of a select group of nearby, southern galaxies displaying strong core activity. It has a morphological classification of Sb-Sd and is located approximately 4 Mpc away (Freeman et al, 1977). Other characteristics are listed in Table 1. The nucleus can be described as `active' based on its strong HO maser (Gardner & Whiteoak, 1982), intense radio (Elmouttie at al, 1995; Harnett et al, 1990) and infra-red emission (Moorwood & Glass, 1984). Minor axis features, possibly indicative of outflows, have been seen in the form of anomalous radio emission (Elmouttie et al, 1995) and an ionisation cone (Marconi et al, 1994). A single carbon monoxide spectrum of the centre of the galaxy observed with the Swedish ESO Submillimeter Telescope (SEST) in 1988 has been presented as well as other spectra of various molecules (Israel 1992). Kinematical evidence for a rapidly rotating OH ring around the core is also available (Harnett et al, 1990).

 
Table 1: Properties of the Circinus galaxy

The Circinus galaxy is one of a few nearby southern galaxies displaying strong core activity. The proximity and activity of the galaxy offer an ideal opportunity to study the molecular gas in the nuclear regions of an active core galaxy. There has been relatively little attention given to this important southern hemisphere object and this has prompted us to further the research on this galaxy at a number of wavebands such as the radio (Elmouttie et al, 1995), the = 21 cm neutral hydrogen line (Jones et al, in prep) and the ionised hydrogen H line (Elmouttie et al, in prep.). Herein, we present results from our observations of the molecular hydrogen gas of the Circinus galaxy using the CO(1-0) line as the tracer.

© Copyright Astronomical Society of Australia 1997