ATNF Science Highlights 2000

First millimetre light for upgraded Australia Telescope

After three years of designing, building and testing, first light at millimetre wavelengths for the upgraded Australia Telescope Compact Array occurred on 30 November 2000. Two of the six antennas were fitted with the new 3-mm receiving systems and were used to observe silicon monoxide maser emission from the Orion nebula.

Massive proto-planetary disks detected at radio wavelengths

Observations taken with the Australia Telescope Compact Array reveal the presence of three sources in the starburst cluster NGC 3603, identified as proto-planetary disks on images from the Hubble Space Telescope and ESO Very Large Telescope. The radio sources are 20 - 30 times larger than their counterparts in the Orion nebula and are much brighter than expected.

New discoveries of millisecond pulsars in globular clusters

Globular clusters are a rich source of millisecond pulsars. These are compact neutron stars in binary systems that have been "spun up' by mass accretion from the companion stars. In a study of 60 globular clusters, ten new millisecond pulsars have been discovered in four clusters which were not previously known to contain pulsars. The new discoveries were made from sensitive observations taken with the Parkes radio telescope.

A very young pulsar discovered in the Parkes Multibeam Pulsar Survey

In the past four years, the Parkes radio telescope and its multibeam receiver have been used to scan the Milky Way for pulsars. The Parkes survey has nearly doubled the number of known pulsars. Among the discoveries is the pulsar J1119-6127 which rotates just over twice per second. Its spin parameters show that it is only 1,600 years old, making it the fourth youngest pulsar known in the Milky Way. Observations taken with the Australia Telescope Compact Array show that the pulsar is at the centre of a previously uncatalogued supernova remnant.

A new test for general relativity

A team of Australian and U.S. astronomers have used the Parkes radio telescope to measure the distortion of space-time near a star 140 parsecs from Earth, confirming a prediction of Einstein's general theory of relativity. They measured the arrival times of the pulses received on Earth from the bright millisecond pulsar, PSR J0437-4715, to within a tenth of a millionth of a second.

The HI environment of superbubbles in the Large Magellanic Cloud

One of the most important processes that drives the evolution of galaxies is the injection of energy into the interstellar medium from the winds and supernova explosions of massive stars. In starburst regions, groups of massive stars may blow "superbubbles" of hot ionized gas which extend over large distances. A team of researchers has used the Australia Telescope Compact Array to study the neutral hydrogen environment around three young superbubbles in the Large Magellanic Cloud. They find that while the ionized gas shells are similar for the three regions, the neutral hydrogen distributions are strikingly different.

The HIPASS Bright Galaxy Survey

The HI Parkes All-Sky Survey has provided the first ever survey of extragalactic neutral hydrogen over the southern sky. The survey was completed in March 2000 and the data were released in May 2000. One of the first survey products is the HIPASS Bright Galaxy Catalogue, a catalogue of the 1,000 brightest HI galaxies in the southern hemisphere.

HIPASS turns up new gas in the NGC 2442 group

The HI Parkes All Sky Survey has revealed a huge cloud of neutral hydrogen gas, near the bright spiral galaxy NGC 2442. The gas cloud, designated J0751-69, contains a thousand-million solar masses of hydrogen but shows no evidence for any stars or star formation activity. The cloud may been torn out of NGC 2442 during a tidal interaction with another galaxy.

Recurrent activity in giant radio galaxies

Giant radio galaxies have linear sizes of millions of light years. Observations taken with the Australia Telescope Compact Array for the giant radio galaxy B0114-476 reveal a "double-double" structure with two outer diffuse lobes and two inner jet-like features. Such a structure suggests that the galaxy may experience recurrent nuclear activity.

The gaseous halos of three spiral galaxies

Observations of three southern edge-on spiral galaxies, taken with the Australia Telescope Compact Array, show that the galaxies have extended gaseous halos. The radio emission occurs from relativistic electrons which are released during multiple supernova explosions. The radio data provide new insights into the star formation history of the observed galaxies.