Millimetre Workshop Abstracts



Geoffrey Blake: Astrochemistry with Millimeter Arrays

The potential role of the ATCA in tracing the chemical evolution of gas and dust from interstellar clouds to planetary systems is discussed and illustrated with recent observational studies of molecules in low- and high-mass young stellar objects. Line surveys using single-dish (sub)millimeter-wave telescopes have been used to develop a chemical scenario that couples active grain-surface chemistry with detailed gas phase models. The validity of this scenario can only be tested with high spatial and spectral resolution observations, and current progress toward this goal will be described. In particular, exploratory observations of the excitation and distribution of molecules in both embedded YSOs and optically visible circumstellar disks will be highlighted.


Tyler Bourke: Star Formation Studies with the mm ATCA



Dinah Cragg: Millimetre Methanol Masers

Class II methanol masers are associated with the early stages of massive star-formation, and the strong masers at 6.6 and 12.1 GHz have been detected at several hundred sites in the Galaxy. Interferometry has established that these two masers usually coincide, both spatially and in velocity. In some sources they are accompanied by weaker methanol masers at frequencies ranging up to 157 GHz. We have used an infrared pumping model to account for these maser lines, and to identify potential new maser candidates. The weaker masers are quite sensitive to the model parameters describing density, temperature etc, so when masers at several frequencies develop simultaneously they provide a probe of the physical conditions in the maser region. This will be illustrated with BIMA observations towards W3(OH) of 9 methanol maser candidate lines in the range 80-115 GHz. Interferometry at both 12 mm and 3 mm with the upgraded ATCA will permit similar studies of the environment of southern star-forming regions.


Steve Curran: Imaging AGN and Starburst Activity in Nearby Seyfert Galaxies

The new millimetre-wave equipped ATCA is ideal for obtaining the first high resolution observations of the molecular gas in NGC 4945 and the Circinus galaxy, the two closest galaxies hosting Seyfert nuclei. We will be able to compare how the distributions of the dense molecular gas differs between the two galaxies, thus enabling us to infer how well the HCN traces the Seyfert or starburst activity, a question which is not as straightforward to answer as previously thought. As well as this, we should, for the first time, be able to image directly molecular outflows in Seyfert galaxies.


Michael Drinkwater: Millimetre wave observations of red quasars

A significant fraction of radio-selected quasars have very red optical to infra-red colours compared to optical quasar samples. Dust is the likely cause of the red colour for some of these quasars and the ideal way to test the dust hypothesis is to detect molecular absorption lines associated with the dust at the quasar redshifts. Several years ago I attempted to detect molecular absorption in red quasars with the Mopra Telescope but this proved very difficult, although one known absorption line was redetected. The new millimetre capacity of the Australia Telescope will make this project much more feasible.


Maria Hunt: Observations of Organic Molecules

A general overview of the chemistry of star-forming regions will be presented, together with a discussion on which molecules best trace different stages of the star-formation process. The results of a targeted survey of dense, southern molecular cores with the single dish Mopra Telescope will also be presented.


Baerbel Koribalski: First 3mm Results

I will present an overview of the various results obtained with the 3mm prototype receivers at the upgraded AT Compact Array. First light was achieved on the 30th of November 2000 using one baseline and one polarisation. Since September 2001 we have a 3-baseline sysetm with 2 polarisations. Special correlator configurations have made it possible to observe molecular lines in galaxies. I will show examples of HCO+ in NGC253 and the Circinus Galaxy. We also searched for red-shifted absorption in the blazar 1921-293. The highlight for me has certainly been the successful observations of HCO+, HNC and HCN absorption in the Centaurus A galaxy.


Cornelia Lang: Molecular Gas in the Galactic Centre Region

The molecular cloud population in the central 200 pc of the Galaxy can be characterized by clouds which are denser, warmer and more filamentary than their disk counterparts. Most of these clouds also reside on non-circular orbits. The interactions between such clouds and the other components of the stellar and ISM medium in this region have been of great interest to Galactic Centre (GC) astronomers for decades. As spatial resolutions of most wavelengths improve, it is crucial to have higher resolution millimetre observations for studying the molecular component in detail. I will talk about three scenarios in the GC for which the new millimetre capabilites of the ATCA are especially relevant: (1) the interplay between molecular material and young stellar clusters, (2) the interaction between molecular material and magnetized filaments, and (3) the correlations between X-ray emission and molecular gas.


Sarah Maddison: Modelling Protostellar Disks

I will present an overview of the current research into modelling circumstellar disks around single stars (protostellar disks), binary stars (circumbinary disks), and planet forming disks (protoplanetary disks). A brief discussion of how millimetre observations can help constrain models will also be presented.


Dick Manchester: The 12mm ATCA system and some recent results

Receivers operating in the 12mm band have been installed on 3 antennas of the AT Compact Array. The receiver systems are interim and may be used for observations on a shared risk basis. The specifications and performance of the receivers will be discussed and some recent results, including the first detection of the radio remnant of SN 1987A at 12mm will be described.


Vincent Minier: The Earliest Stages of Massive Star Formation

The investigation of massive star formation is vital to our complete understanding of galactic composition and evolution because massive stars actively participate in the heating of the molecular clouds and in the enrichment of the interstellar medium in heavy elements. Based on previous single dish and interferometric mm observations of "northern" hemisphere sources, we propose to extensively study the stellar content of young massive star clusters with the upgraded ATCA at both 12 mm and 3 mm. The selected clusters exhibit methanol maser that is used as a criterion of extreme youthfulness. Such observations would allow us to study the chemical differentiation within massive star-forming regions as well as the degree of ionisation of the (proto)stellar envelope at the earliest stages of massive star formation.


Georgij Rudnitskij: Molecular masers in variable stars

Results of long-term monitoring of late-type variable stars (Mira-type and semiregular) in the H2O line at 1.35 cm (22-metre radio telescope in Pushchino), as well as simultaneous optical spectroscopy (Crimean Observatory of the Sternberg Astronomical Institute), are reported. The observed correlation between the flares in the Balmer lines and subsequent outbursts in the H2O lines is interpreted in the framework of a shock wave model. Tests for this interpretation, consisting in repeated mapping of the stars in the H2O line and the continuum, feasible with ATCA observations, are proposed. Some prospects of ATCA observations of late-type variables at millimeter wavelengths are discussed.


Bob Sault: Water vapour radiometry at the ATCA

By the standards of millimetre interferometers, the ATCA site is quite a poor one. Atmospheric phase and opacity will significantly limit the season where the array can be used for millimetre operation. Water vapour radiometry is a method to sense the atmospheric phase by measuring water emission in the atmosphere. I describe the ATCA's prototype radiometers and some results. The prototypes estimate the phase with an rms error of 350 microns. Our aim is to reduce this to an error of 100 microns.


Robert Smith: Dust and Ice in Bipolar Outflows

Bipolar outflow sources present us with a huge range in physical conditions in which to study gas and dust. We have the relatively benign conditions in the outer regions of circumstellar disks around the central stars of outflow sources, where the dust grains may be able to grow by coagulation and where it is sometimes dense enough and cold enough for water ice to form on the dust grains. Contrast this to the conditions both within the outflows and where the outflow interacts with the surrounding medium. We have begun studying the conditions under which dust grains can be modified in bipolar outflow sources by combining infrared imaging with modeling we have done of the scattering and extinction properties of dust particles. However, in order to learn more about the chemical/dynamical states of these objects we need to turn to other observational techniques, one of which is mm-interferometry. In this talk we will try and present a summary of the potential science questions connected with bipolar outflow sources by looking at a few relatively well-known examples of outflows associated with both young and evolved stars.


Andrei SOBOLEV: Maser and Star Formation Studies in the Millimeter Range

Results of single dish and interferometry studies of masers and their environment in millimeter range will be discussed. Special attention will be paid to the issue what can millimeter interferometry tell us about the nature of star formation phenomena in the regions where masers are formed. At present interferometrical data in millimeter range is available only for northern maser sources while the bulk of massive star forming regions is situated in the southern sky. Best prospects among the southern methanol maser sources will be discussed.


Mark Wardle: Shock waves in molecular clouds

Shock waves provide a temporary warm and dense environment for chemistry to occur in molecular clouds. I shall discuss the prospects for detecting the chemical signatures of shock waves with the upgraded AT, and indicate how these observations may bear on some important theoretical issues.


Tommy Wiklind: Molecular line emission and absorption from high-z galaxies

The current status of millimeter line observations of molecular gas in distant galaxies will be reviewed and future progress discussed.


Warwick Wilson: Future Enhancements of the ATCA.

Plans for future enhancements of the Australia Telescope Compact Array, in particular those which will lead to an improved performance at millimeter waves, will be presented. A new backend system for the array will be described. This will increase the maximum bandwidth to 2GHz.


Tony Wong: ATCA as a Millimetre Interferometer

I will discuss the present capabilities of the ATCA at wavelengths of 3 and 12 mm and compare ATCA with other millimetre arrays. Current limitations, including sensitivity and baseline & frequency coverage, will be discussed, as well as plans to overcome them. I will also discuss observing strategies peculiar to mm wavelengths and how to obtain further help in planning your observations.


Chris Wright: Millimetre wave observations of pre-planetary disks

The Australia Telescope mm-wave upgrade offers the first opportunity in the southern hemisphere to image the disks surrounding young stars in both molecular tracers and dust continuum. We have begun a project firstly at Mopra and recently at the AT to attempt such observations. I will describe the possible scientific return from such a project, as well as present some first results and future prospects.


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