K. L. Jones

ATCA HI observations of the peculiar galaxy IC 2554

ATCA H I and radio continuum observations of the peculiar southern galaxy IC 2554 and its surroundings reveal typical signatures of an interacting galaxy group. We detected a large H I cloud between IC 2554 and the elliptical galaxy NGC 3136B. The gas dynamics in IC 2554 itself, which is sometimes described as a colliding pair, are surprisingly regular, whereas NGC 3136B was not detected. The H I cloud, which emerges from IC 2554 as a large arc-shaped plume, has a size of similar to30 kpc, larger than that of IC 2554. The total H I mass of the IC 2554 system is similar to2 x 10(9) M., one-third of which resides in the H I cloud. It is possible that tidal interaction between IC 2554 and NGC 3136B caused this spectacular H I cloud, but the possibility of IC 2554 being a merger remnant is also discussed. We also detected H I gas in the nearby galaxies ESO 092-G009 and RKK 1959 and an associated H I cloud, ATCA J1006-6710. Together they have an H I mass of similar to4.6 x 10(8) M-.. Another new H I source, ATCA J1007-6659, with an H I mass of only similar to2.2 x 10(7) M. was detected roughly between IC 2554 and ESO 092-G009 and corresponds to a face-on low surface brightness dwarf galaxy. Star formation is evident only in the galaxy IC 2554 with a rate of similar to4 M. yr(-1).

12CO J = 1 - 0 observations of the Circinus galaxy using the Mopra 22 M radio telescope

The J = 1 - 0 rotational transition of carbon monoxide has been used to trace the molecular gas at five different positions in the Circinus galaxy using the Australia Telescope National Facility 22 m radio telescope at Mopra. The intensity profile of the central CO emission has a full width at half maximum of 550 pc. The 12CO (1 - 0) spectrum at the centre of the galaxy has an integrated temperature of 145 K km per sec, with components peaking at 0.62 K and ranging in velocity from 200 - 600 km per sec. The total mass of molecular gas in the Circinus galaxy, assuming the CO intensity profile of the galaxy is similar to the radio continuum, is estimated. This estimate, combined with previously published far infrared data, yields a value for the star forming efficiency.

Deep Survey of the Radio Continuum Emission along the Southern Galactic Plane at 2·4 GHz

We have just completed the observational stage of a 2·4 GHz survey of the Southern Galactic Plane, using the Parkes radiotelescope, between 238° ≤ l ≤ 365° and with a latitude range of at least | b | ≤ 5° (beamwidth ~9 arcmin). The survey details both continuum emission and linear polarisation down to rms noises of approximately 12 and 4 mJy/beam respectively. It is the most sensitive survey to date of the southern plane at this frequency and should nicely complement the Effelsberg northern plane surveys in addition to the recent southern surveys such as the 843 MHz MOST survey and the 5 GHz PMN survey. The total-power maps are now completed, and reduction of the polarisation data is still in progress. In addition to compact HII regions and extragalactic sources, we are detecting on our total-power images a considerable amount of large-scale structure, and a significant number of new SNR candidates and spur-like features.

Narrow Band HI System for the Parkes Telescope Multibeam Package

A narrow-band translator and filter system has been constructed for the Parkes Multibeam receiver. This brief note outlines the characteristics of the system and indicates the range of new projects that will be possible in studies of the Magellanic Clouds.