New Telescope Will Open Up Southern Skies

The Lagoon Nebula is a region about 3800 light years away in which stars of high mass and luminosity are being born, emitting enough ultraviolet radiation to stimulate atoms in the surrounding gas clouds to emit light. This eerie glow typical of an 'emission nebula' is shown in this colourful SALTICAM image, produced by combining images in three filters: 120 sec in U, 20 sec in V and 40 sec in I. The image is about ten arcminutes across (a third of the apparent width of the full moon in the sky), which corresponds to about 10 light years at the distance of the Lagoon. The entire cloud extends over 300 light years, while the region viewed here includes the youngest stars and the fascinating Hourglass nebula (the brightest feature in the image).

A new telescope on the edge of the Kalahari Desert has just released the first images it has captured of the skies above the southern hemisphere. The Southern African Large Telescope (SALT) was constructed by an international consortium of universities and government agencies. The parties include the National Research Foundation of South Africa, the University of Wisconsin-Madison’s College of Letters and Science, Poland’s Nicolas Copernicus Astronomical Centre and Rutgers University. The $18 million telescope uses 91 hexagonal mirror segments in a 10 meter by 11 meter array.

Astronomers are excited to at last have a large optical telescope available in the astronomically rich southern hemisphere. “The southern Milky Way is more spectacular and provides a richer treasure trove of objects than the northern Milky Way,” said Eric Wilcots, a UW-Madison professor of astronomy. “We’re now players in the world of large telescopes. We’re in an age in which answering the big, fundamental questions requires access to large telescopes in good, dark skies. SALT is just such a telescope.”

A huge advantage for the SALT Telescope is its location in one of the darkest regions of the world. With no nearby cities or towns, the observatory will be little affected by the light pollution that hampers many observatories in the Northern Hemisphere.

Wilcots said that the southern sky promised a bounty of observing. Studies of thousands of individual stars in the Magellanic Clouds are planned to trace the history of those nearby galaxies. The results of those studies, Wilcots explains, can be extrapolated to galaxies in general, providing a more refined life history of objects like our own Milky Way.

Other southern sky objects of interest include Eta Carina, a nearby massive star that has been racked by a series of enigmatic and spectacular explosions over the past century; Omega Centauri, a globular cluster of stars in the Milky Way that some astronomers believe may be the fossil remains of another galaxy consumed long ago by the Milky Way; and Centaurus A, a nearby galaxy that recently experienced an explosion at its core.

The astronomers are now integrating into the observatory the primary scientific instrument for the telescope, a device known as the Prime Focus Imaging Spectrograph. When in place above the primary mirror array, the device will give the telescope specialized capabilities to capture and analyze starlight in unprecedented ways. The spectra the astronomers obtain will provide far more information than simple images, helping show the chemical makeup of objects, depict motion, and capture some wavelengths of light that enable the telescope to see through the obscuring clouds of dust and gas that permeate space.

The SALT Observatory, says Wilcots, is “a beacon for Southern African science. It is meant to inspire a new generation of African scientists, which will be the lasting value of SALT to Southern Africa.” He added that there were only a handful, perhaps as few as three, black South Africans with Ph.Ds in astronomy. “While we have problems with an underrepresented minority in science, South Africa has an underrepresented majority.”

More Images from SALT

Source: University of Wisconsin-Madison
Pic courtesy SALT


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