Research School of Astronomy & Astrophysics

OTHER HIGHLIGHTS

Gemini

On February 18 the Minister for Education, Dr David Kemp, announced that Australia would join the International Gemini Project. Gemini is a partnership of funding agencies: the National Science Foundation in the USA, the Particle Physics & Astronomy Research Council in the UK, the Canadian NRC, the Chilean CONICYT, corresponding agencies in Brazil and Argentina, and now the Australian Research Council (ARC). Gemini is building two 8.2 metre optical/infrared telescopes, one at Mauna Kea Observatory in Hawaii, and the other at Cerro Pachon in Chile.

Administrative arrangements for Australian participation progressed rapidly during the year. In May the Chair of the ARC, Professor Vicki Sara, signed the revised Gemini agreement, giving Australian astronomers a 4.73% share in the use of the telescope. In October the Australian Gemini Steering Committee was formed for the purpose of advising the Australian government on Gemini and for oversight of the Australian Gemini Office, a facility which is mirrored in each of the partner countries. The Australian Gemini Board member, Professor Lawrence Cram of the University of Sydney, attended his first meeting and opening of the new international headquarters in Hilo, Hawaii in November.

The Australian Gemini Office is currently unfunded, and this is a matter for the ARC to rectify in due course. The Steering Committee has received a proposal for its location at Mount Stromlo Observatory. An Australian Gemini Science Advisory Committee is operational (again reflecting arrangements by the other partners), and is chaired by Project Scientist, Dr Gary Da Costa of RSAA. The Gemini North telescope will see "first light" early in 1999.

Awards

The year saw a number of international awards to the School's academic staff. Details are given in section 10 of this report. Highlights included Dr Brian Schmidt's selection for Science's top science breakthrough of 1998. This was for the work on distant supernovae and the geometry of the Universe, which was highlighted in our annual report last year. Science is the magazine of the American Association for the Advancement of Science. In addition, Professor Ken Freeman became a Fellow of the Royal Society, and the Director became the third successive Oort Professor with an ANU affiliation. The Oort professorship is a visiting appointment at the University of Leiden in the Netherlands and is selected annually.

The Third Stromlo Symposium

The Research School of Astronomy & Astrophysics has a long tradition in the investigation of the material which constitutes the halo of the Milky Way, including three decades study of the halo's luminous component and the more recent five year search for its elusive dark material by the MACHO consortium. In August the Third Stromlo Symposium, entitled "The Galactic Halo: Bright Stars & Dark Matter" was held at the Australian Academy of Science. The meeting was held in honour of the late Professor Alex Rodgers, whose work on the kinematics and chemistry of the luminous halo had been capped in recent years by his leadership of the project to rebuild the

Great Melbourne Telescope expressly for the MACHO project.

Annual Report 1998

The contrast between the bright and dark matter in the halo is stark. The luminous material accounts for less than 1 percent of the mass of the Galaxy: the dark matter may account for more than 80 percent of it. The luminous material has been well studied and has led to a fairly clear picture of the manner in which the Galaxy formed: no-one knows what the dark matter is! In the context of the bright material someone from an earlier era might well have said "Never in the history of mankind has so much been known about so little": and in the context of dark matter "and never has so little been know about so much".

Some 110 astronomers and astrophysicists from 17 countries met to discuss and seek to understand the relationship between the bright and dark matter. Their interests broadly divided into three areas: the stellar halo, the gaseous halo, and the dark halo. The program mixed the various topics in such a way as to maximize interaction. Together with the high-quality posters, this ensured there was much to learn for everyone.

The delegates were presented with new results from surveys on the abundances, space motions, and ages of the oldest stars in the Galaxy, and the search for substructure in the system. There was much interest in the details of the encounter of the Large and Small Magellanic Clouds with the Milky Way, and talks on observations of the high velocity clouds and stars of the Magellanic Stream, on theoretical models of the encounter, and on the possible involvement of the Sagittarius dwarf spheroidal galaxy. The implications of the 20 microlensing events (MACHOs) observed towards the Large Magellanic Cloud were the topic of much discussion, and focussed on possible alternatives to the classical interpretation of their resulting from dark objects of 0.5 solar masses in the Galactic halo. All possibilities were canvassed. Brown dwarfs seem excluded, while white dwarfs and neutron stars have problems. Some favoured ultra-cold clumps of molecular hydrogen, while others argued for ionized gas at a million degrees. There was discussion also of more exotic candidates such as massive neutrinos, axions, neutralinos, and primordial black holes.

It came as no surprise that no solution was reached. One may hope that before too many more Stromlo Symposia have been held, a clearer understanding of the nature of the dark matter will have emerged.

Live from Stromlo

The Stromlo Exploratory was chosen as the venue for Japanese NHK TV's Voyage to the Galaxy. The live broadcast on August 21 consisted of a pair of two hour programs in this public channel's Live Space Special series. The first of the pair was directed to children and involved the participation of science students from Chapman High School in the ACT and a second group at a Tokyo public science facility. Live link-ups were also made with Mount Wilson, California and Villafranca, Spain. Several of the Research School's astronomers described their work in illustrated interviews. A number of visiting scientists participating in the Third Stromlo Symposium also talked about the nature of dark matter and its detection, a subject which fascinates both the public and astronomers alike. With the producer's permission we are condensing the video for playing at the Exploratory.

Other special events at the Exploratory during the year included Discover Your National Capital, the Leonids meteor shower, and a first birthday celebration on 25 July. We should also record the formation of an Observatory Exploratory Liaison Committee, aimed at increasing the interaction of the academic staff in public outreach through the Exploratory. Mr Alister Graham designed and developed the Exploratory web pages.

Research School of Astronomy & Astrophysics

The Fundraising Campaign to equip the Stromlo Exploratory reached its halfway mark during the year. Potential corporate sponsors will be interested in the results of a recent Melbourne Institute survey, which indicated that science is second only to sport as an area of Australian achievement of which our compatriots are proud.