Johannesburg Centre, Astronomical Society of Southern Africa


Galaxy Morphology Conference

There is clearly something going on in the Universe. I dropped my sandwich this morning and it landed with the jam side up. It could be because of the strange RVC (Rotational Velocity Curve) in AGN’s (Active Galaxy Nuclei) or perhaps dust clouds in high Z (zee) spirals. Maybe the million degree ISM (Inter-Stellar Medium) in LSB (Low Surface Brightness) galaxies has something to do with it. The cosmic FIR (Far Infra Red) reveals resonance rings never before suspected and who knows what they do? The MLR (Metallicity Luminosity Relationship) depends on the SFR (Star Formation Rate) in all galaxies with medium zee.

These are just some of the buzz words you would have picked up if you had been attending the Galaxy Morphology conference held in Midrand in September. Some of the world’s top astronomers were there, including the science director of the Hubble telescope, a director of the Keck telescope, a director from the Space Telescope Science Institute, the director of the Space Infra Red Telescope (SIRTF) ......and....and....and.…..(Trevor Gould was also there).

Although this conference had as its title "Towards a new millenium in Galaxy Morphology", the 80-odd talks covered all aspects of modern astronomy. There was a slant to the study of galaxies in many different wavelengths, from UV tofar IR and then radio frequencies, but topics such as the origin of life on Earth were touched on, as well as talks on new telescope facilities. David Buckley, from SAAO talked on SALT (South African Large Telescope) and Barbara Cunow from Unisa talked on her studies of Sb galaxies, done with the 1-meter telescope at Sutherland.

Many speakers referred to the HDF (Hubble Deep Field) - that fantastic picture taken by Hubble of 3000+ distant galaxies that looked so impressive and, it seems, contained enough data to keep 50 astronomers busy for a number of years. There was also excitement about the NGST (the next generation space telescope) that will take the place of Hubble one day. Most of these astronomers want to see deeper and deeper into space, and they want bigger and better telescopes. They talk of redshifts of zee=10, which brings you back about 90% of the age of the universe, and there are some strange objects at that age. One puzzle is why supernovae in the very early galaxies look similar to supernovae we see in local galaxies today.

But the one topic that came up repeatedly was Dust. Dust in near and far galaxies is one thing they don’t really have a handle on. What is the dust? How big are the particles? And how much of the visible universe does it mask? 95% of the bolometric radiation is hidden from us. Galaxies seem to have lots more dust than visible stars. The problem of unmasking galaxies has been tackled by David Block, who subtracts the dust radiation from visible pictures of galaxies and has revealed that the galaxies are many times bigger than they appear to be.

One paper showed proof of a massive black hole in a galaxy core, and evidence that their are probably black holes in the cores of most spiral galaxies. Very interesting Another paper showed that star formation in spiral galaxies occurs in well-defined rings and not at random throughout the galaxy. And then it was shown that there are galaxies consisting of gas and dark matter but no stars. Surprise! The galaxy names cited look like telephone numbers.

The conventional Hubble sequence of galaxy morphology was shown to be erroneous and much debate arose as to how to replace it, and with what classification system.

Supernovae occur in our galaxy about every 30 years. Wouldn’t it be exciting to see one.

If you thought that astronomers have all they answers you are way off. They don’t. There are huge questions to be answered - enough work to keep many astronomers busy for the next millenium.

One thing I learned - one should be careful about making predictions, especially about the future.

Brian Fraser


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