Welcome to the Pretoria Branch website of the Southern Africa Association for the Advancement of Science, also better known as S2A3. The Association celebrated it Centenary year in 2002. Please see the "About us" section for more information on the history of the Association.

The Pretoria Branch organizes public, popular lectures during the year. See the "Archive" section for an overview of past lectures.

We hope you find our website informative as far as the activities of the Association are concerned. Please forward any queries or suggestions about this website to the Webmaster.

The Southern Africa Association for the Advancement of Science is a non-profit organization with the following objectives:

1.	Promotion of contact between associations, groups and individuals, professionals as well as laymen, who are interested in all aspects of science and related activities.
2.	To initiate or organise gatherings and excursions with a scientific theme.
3.	To promote scientific and human activities which are environmentally friendly.
4.	The promotion of a scientific approach to education.

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If you would like to contact the Association, please contact the Honorary Secretary:

We know nothing in reality; for truth lies in an abyss.

Democritus, (c. 420 BCE) Greek philosopher.

Resembling the puffs of smoke and sparks from a summer fireworks display in this image from NASA's Hubble Space Telescope, these delicate filaments are actually sheets of debris from a stellar explosion in a neighboring galaxy. Hubble's target was a supernova remnant within the Large Magellanic Cloud (LMC), a nearby, small companion galaxy to the Milky Way visible from the southern hemisphere.

Denoted N 49, or DEM L 190, this remnant is from a massive star that died in a supernova blast whose light would have reached Earth thousands of years ago. This filamentary material will eventually be recycled into building new generations of stars in the LMC. Our own Sun and planets are constructed from similar debris of supernovae that exploded in the Milky Way billions of years ago.

This seemingly gentle structure also harbors a very powerful spinning neutron star that may be the central remnant from the initial blast. It is quite common for the core of an exploded supernova star to become a spinning neutron star (also called a pulsar - because of the regular pulses of energy from the rotational spin) after the immediate shedding of the star's outer layers. In the case of N 49, not only is the neutron star spinning at a rate of once every 8 seconds, it also has a super-strong magnetic field a thousand trillion times stronger than Earth's magnetic field. This places this star into the exclusive class of objects called "magnetars."

The Hubble Heritage image of N 49 is a color representation of data taken in July 2000, with Hubble's Wide Field Planetary Camera 2. Color filters were used to sample light emitted by sulfur ([S II]), oxygen ([O III]), and hydrogen (H-alpha). The color image has been superimposed on a black-and-white image of stars in the same field also taken with Hubble.

Image Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Acknowledgment: Y.-H. Chu (UIUC), S. Kulkarni (Caltech) and R. Rothschild (UCSD)