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RE: Salt First light
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Title: Astrophysics in Southern Africa
Authors: Patricia A. Whitelock

The government of South Africa has identified astronomy as a field in which their country has a strategic advantage and is consequently investing very significantly in astronomical infrastructure. South Africa now operates a 10-m class optical telescope, the Southern African Large Telescope (SALT), and is one of two countries short listed to host the Square Kilometre Array (SKA), an ambitious international project to construct a radio telescope with a sensitivity one hundred times that of any existing telescope. The challenge now is to produce an indigenous community of users for these facilities, particularly from among the black population which was severely disadvantaged under the apartheid regime. In this paper I briefly describe the observing facilities in Southern Africa before going on to discuss the various collaborations that are allowing us to use astronomy as a tool for development, and at the same time to train a new generation of astronomers who will be well grounded in the science and linked to their colleagues internationally.

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Sutherland might be the coldest town in South Africa, with temperatures below -6C this weekend, but it is still a mecca for astronomers from across the world, who come to visit Salt - the South African Large Telescope.
This is one of the largest single lens telescopes in the world, with a diameter of nearly 10 metres.
It is designed not for imaging, but for spectroscopy, making it a unique resource for those looking to discover the atmospheric or inner workings of stars and planets across the universe.

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SALTICAM Proposals
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Call for SALTICAM Proposals
The proposals will be for the period 15 Dec 2006 30 June 2007.
The deadlines are as follows:
Observing Period Deadline
=======================
Dec - Feb 15 Dec
April - June 15 Jan

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Salt News
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SALTeNEWS for November has been released.

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SALT
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One year on...
The Southern African Large Telescope (SALT), was inaugurated on the 10th November 2005.

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RE: Salt First light
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Stobie-SALT Scholarships in Astronomy and Astrophysics for 2007
The Stobie-SALT Scholarship Programme in Astronomy and Astrophysics is an initiative aimed at producing the next generation of South African astronomers and astrophysicists through the provision of scholarships for doctoral level study at local and international universities. The scholarship programme is named after the late Dr Bob Stobie, former Director of the South African Astronomical Observatory (SAAO) and former Chair of the Board of the Southern African Large Telescope (SALT). SALT was inaugurated by President Thabo Mbeki on 10th November 2005 and is the largest single optical/infrared telescope in the southern hemisphere, requiring appropriately trained astronomers and astrophysicists.

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SALT
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Southern African Large Telescope (Salt) at Sutherland

SALTsatimage
Expand (218kb, 707 x 536)
Longitude 2049'52.79"E Latitude 3224'3.80"S


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Salt First Science
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Way out in the universe a red giant is being mugged by a white dwarf.

And although the battle galactic is happening a staggering 400 light years away, astronomers at the Southern African Large Telescope (Salt) at Sutherland in the Karoo are able to observe the event.
Yesterday, astronomers from the SA Astronomical Observatory said these observations formed the first "serious science" to come out of the telescope, which was inaugurated in November last year.
Darragh O'Donoghue, principle investigator at Salt, has written up the findings with 50 co-authors, which has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.

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-- Edited by Blobrana at 16:51, 2006-08-17

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First Science with SALT
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The Southern African Large Telescope (SALT), inaugurated in November 2005, is today releasing its first public research results, giving new insight into an exotic pair of stars closely orbiting one another.

This research uses a strength of the SALT design which is rare among large telescopes, the ability to take 'snapshots' of stars in very quick succession, so that we can study the rapidly changing properties of compact stars, especially as they pull in gas from their companions or surroundings.
The gravitational field of a compact star commonly pulls in gas from a companion star -- the radiation (especially X-ray) emitted as this happens is one of the indirect ways we use to detect black holes. It's also the way that mass builds up on some compact stars until supernova explosions blow them apart, giving us the 'Type Ia' supernovae recently used to show that the expansion of the universe is speeding up.
The new SALT results are for a 'polar' binary star system, which contains a compact star called a 'white dwarf' a star which has used up its original store of nuclear energy, then shrunk to about one millionth of the volume of a star like our sun. In a polar this 'white dwarf' also has a very strong magnetic field, which strongly influences how the hot gases from its relatively ordinary companion reach the white dwarf surface.
Polars are the most readily accessible objects we know for studying gas accretion in strong magnetic fields, and are among the closest orbiting pairs of stars we know: both stars and their orbits would fit inside the Sun!
The polar which SALT has studied takes only one and a half hours to complete an orbit (compared to a month for the earth and moon, and a year for the earth and sun). Despite being a pair of stars, they are so close you would see them as only one star in a telescope. One of the stars is an ordinary star like the Sun, but cooler, redder and about 1/3 of the Sun's mass and radius. Its 'white dwarf' companion is hundreds of thousands of times as dense of the Earth -- a chunk of white dwarf as large as a pair of dice would weigh as much as two small trucks. This gives the white dwarf an intense gravitational field that sucks in material from the larger star. But it is the white dwarf's huge magnetic field (30 million times as strong as the Earth's) that forces the gas from the cool star to impact at the white dwarf's magnetic poles. Figure 1 is an artist's impression of what such a typical such binary system might look like: the cool, red star is in the background with the stream of gas being sucked off by gravity shown in white, finding its way down to the white dwarf along a path shaped by magnetic forces.
Imagine now that you are looking at a binary system like this from "behind" the cool, red star with your viewing angle such that the red star, once an orbit, passes in front of the white dwarf and cuts off your view of it. If you had a telescope like SALT, and a camera on it like SALTICAM, which can make brightness measurements every 100 milliseconds, you would see the brightness of the system dim quite drastically because the light from the gas crashing on to the magnetic poles of the white dwarf completely outshines the light from everything else.

SALTscience2
This shows a cartoon of your view of the system at the start of eclipse (left) when the red star is just about to block our view of one magnetic pole, labelled Spot 2, and at the end of eclipse (right) when the red star has just uncovered Spot 2.

SALTscience
A sequence of brightness measurements and the evidence for what has just been described can be seen in the sequence. If you look closely, you will see it has a first sudden brightness drop disappearing), followed about 25 seconds later by a second sudden brightness drop. Towards the end of the sequence there are sudden rises in brightness corresponding to the earlier sudden drops as the spots are uncovered. The gas stream between the stars also gives some light, and this accounts for the rounded shape of the bottom of the eclipse.

This sequence of measurements is better than anything that has been obtained before, and SALT's advantages over all other large telescopes for this type of research should allow SALT astronomers to lead in probing the mysteries of these 'cannibal stars'.

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SDSS J015543.40+002807.2
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Title: First science with SALT: peering at the accreting polar caps of the eclipsing polar SDSS J015543.40+002807.2
Authors: D. O'Donoghue, D.A.H. Buckley, L.A. Balona, D. Bester, L. Botha, J. Brink, D.B. Carter, P.A. Charles, A. Christians, F. Ebrahim, R. Emmerich, W. Esterhuyse, G.P. Evans, C. Fourie, P. Fourie, H. Gajjar, M. Gordon, C. Gumede, M. de Kock, A. Koeslag, W.P. Koorts, H. Kriel, F. Marang, J.G. Meiring, J.W. Menzies, P. Menzies, D. Metcalfe, B. Meyer, L. Nel, J. O'Connor, F. Osman, C. du Plessis, H. Rall, A. Riddick, E. Romero-Colmenero, S.B. Potter, C. Sass, H. Schalekamp, N. Sessions, S. Siyengo, V. Sopela, H. Steyn, J. Stoffels, J. Stoltz, G. Swart, A. Swat, J. Swiegers, T. Tiheli, P. Vaisanen, W. Whittaker, F. van Wyk

Researchers describe briefly the properties of the recently completed Southern African Large Telescope (SALT), along with its first light imager SALTICAM. Using this instrument, they present 4.3 hours of high speed unfiltered photometric observations of the eclipsing polar SDSSJ015543.40+002807.2 with time resolution as short as 112 ms, the highest quality observations of this kind of any polar to date. The system was observed during its high luminosity state. Two accreting poles are clearly seen in the eclipse light curve. The binary system parameters have been constrained: the white dwarf mass is at the low end of the range expected for cataclysmic variables.
Correlations between the positions of the accretion regions on or near the surface of the white dwarf and the binary system parameters were established. The sizes of the accretion regions and their relative movement from eclipse to eclipse were estimated: they are typically 4-7 deg depending on the mass of the white dwarf. The potential of these observations will only fully be realised when low state data of the same kind are obtained and the contact phases of the eclipse of the white dwarf are measured.

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