NASSP Colloquium Feed

Technological applications of Geomagnetic field measurements at SANSA Space Science

deanne — Tue, 25 Oct 2011 13:07:32 +0200

We all know that the Earth is surrounded by a relatively weak magnetic field which protects us from radiation from the sun and in that capacity makes life possible on Earth. This geomagnetic field is not stationary but changes all the time. We can’t significantly change this field, nor can we switch it off or control it, however, we can measure it and use it to our advantage.

Geomagnetic measurements have been used for centuries by seafarers to navigate with a magnetic compass, but today we use measurements of the geomagnetic field for navigation and orientation control of satellites, some as small as 10cm³, unmanned aerial vehicles such as spy-planes, weapon systems, underwater unmanned rovers and many more. We can also use measurements of the geomagnetic field to find magnetic objects (both stationary and fast moving objects), or to hide magnetic objects from someone else... We are even attempting to predict earthquakes with super cooled magnetic sensors!

Elda Saunderson is a specialist electronic engineer in the Technology Group at SANSA Space Science in Hermanus. Elda joined the previous Hermanus Magnetic Observatory (now SANSA Space Science) in 1995 and has been there since. She has a Masters degree in Electronic (Biomedical) Engineering from the University of Stellenbosch (M. Eng 1995). Elda is involved with applied research and the provision of related services. These services are provided to clients in the defence and aerospace industry and are related to problems and services in navigation, orientation, magnetic measurements and the integration of low cost sensors. This includes high technology development in terms of the calibration of magnetic sensors on dynamic platforms, magnetometer based systems, specialised coil systems, magnetic spin sensors, signature management of magnetic targets and flight test support and evaluation.

A Search for Intermediate-Mass Black Holes at the Centers of Nearby Dwarf Galaxies

deanne — Thu, 13 Oct 2011 10:10:34 +0200

The correlation between black hole (BH) mass and the bulge velocity dispersion is well established for early-type galaxies having a supermassive BH in the centers. The extrapolation of this relation to the lower BH-mass regime is strongly dependent on the existence of BHs in the mass range of 10^3-10^6Msun - called the "intermediate-mass" black hole (IMBH). The BH mass versus velocity dispersion relation infers the existence of IMBHs in dense stellar environments having dispersion in the range of 20-100km/s. Dwarf galaxies are well known to have central velocity dispersions in this range making them ideal candidates for hosting an IMBH. In this talk, I will present an ambitious project for the search of IMBHs using the Southern African Large Telescope (SALT). In particular, the results of a pilot study in the search of these objects at the center of nearby dwarf galaxies using the SALT spectrograph will be shown. Even though the presence of an IMBH in the galaxy center remains inconclusive with the current data, these results do however give a great deal of insight into the capabilities and limitations of SALT in our search for the elusive IMBH.

Bonita obtained her PhD from UCT in 2009 and is currently a postdoctoral research fellow at the SAAO. Her research interests include studying the properties and characteristics of the faintest galaxies - broadly known as dwarf galaxies - that we observe in the nearby universe.

The Cold Gas in Early-Type Galaxies: Past, Present, and Future

deanne — Mon, 10 Oct 2011 09:09:14 +0200

Abstract: The process by which early-type galaxies form remains a key issue in the general theory of galaxies. The traditional view is that early-type galaxies are old systems that formed at high redshift, passively evolving until the present without further star formation activity. In recent years a wide variety of observational work has suggested that the formation of early-type galaxies is in actuality a very intricate process; it has been drawn out over most of a Hubble time and it is even continuing at some reduced level now. For instance, GALEX observations find UV emission from current star formation in up to 30% of nearby ellipticals. Some of the early-type galaxies have stellar population age gradients, with the central stars of the galaxy several Gyr younger than the outer stars. Many early-type galaxies also have internal structures with kinematic properties that are dramatically different from the rest of the galaxy; these kinematically decoupled cores are probably the result of a dramatic merger or accretion event. It is clear that the cold gas in early-type galaxies holds important clues to their evolutionary history--- it serves as a tracer of past accretion or interactions. It is now well established that many early-type galaxies contain detectable amounts of cold gas, sometimes settled in a disc, and recent star formation. In this talk I will discuss what the current observational evidence suggests about the origin of early-type galaxies and their gas contents.

Danielle Lucero is one of the new SKA SARChI Postdoctoral Fellows here at UCT. She obtained her PhD in Physics (dissertation in Astrophysics) at the New Mexico Institute of Mining and Technology in March of this year. Her research interests include the interstellar medium and star formation in early-type galaxies.

The new South African Space Agency (SANSA): Space Weather - what’s up?

deanne — Mon, 03 Oct 2011 10:08:05 +0200

Speaker: Dr Pierre Cilliers, Pr.Eng

Research Physicist in the Space Science Directorate of the South African Space Agency (previously the Hermanus Magnetic Observatory)

Abstract:

SANSA was appointed in June 2007 as the African Regional Space Weather Warning Centre for Space Weather of the International Space Environment Service (ISES). The vulnerability of modern communications and electrical power distribution technology to space weather events is one of the reasons for SANSA’s research on Space Weather and for South Africa’s cooperation with various institutions on the design and development of a space weather payloads for satellites.

About the speaker:

Dr Pierre Cilliers participated in an Antarctic expedition in December 2007 and an expedition to Marion Island in April 2010 to promote international research on Space Weather and is currently the SANSA PI for a project on Geomagnetically induced currents.

Dr. Cilliers will present challenges and opportunities for research in Space Physics and Engineering which relate to the following areas

space weather observations inter alia in Antarctica, on Marion Island, on Gough Island , with an emphasis on recent intense solar events.
the prediction and mitigation of space weather impacts on technology, particularly on electrical power systems,
the development of space weather sensors for CubeSats

The Earth’s Atmosphere and its Impact on Solar Radiation

deanne — Tue, 27 Sep 2011 17:03:47 +0200

Abstract: The Earth’s Atmosphere affects incoming radiation from the Sun or astronomical sources in a variety of ways. The talk will review the state of knowledge about the extinction properties, refraction and night sky brightness. It summarises Rayleigh and Mie scattering processes and how these depend on the wavelength of radiation. Finally, the talk will highlight opportunities for the utilization of SAAO archival astronomical observational data for atmospheric studies.

Speaker Profile: Hartmut Winkler obtained his PhD in Astronomy at the University of Cape Town in 1990. He has since been a Senior Lecturer and Professor in Physics at Vista University in Soweto, an more recently at the University of Johannesburg. His research interests include Active Galactic Nuclei (particularly the spectra and variability of Seyferts) and Solar Irradiation. He has also done work in B[e]-stars, novae, B-stars in the infrared and aerosols.

Nature or Nurture - neutron stars in X-ray binaries in the SMC

deanne — Tue, 27 Sep 2011 17:02:20 +0200

Abstract: The population of Be/X-ray binaries in the Small Magellanic Cloud is proving a superb, homogeneous sample of this type of HMXBs. They are all at the same distance, the same extinction and probably born around the same time. As such we can use this sample of over 50 systems to explore evolution and accretion processes in these systems. In particular, recent results we have just published in Nature suggest the existence of two types of neutron stars, possibly linked to the two proposed types of SN explosions. So is it birth, or the environment, that important in dictating how they behave when they are grown up?

Speaker Profile: Malcolm Coe did his PhD at Imperial College, London, and then worked for several years at NASA/Goddard Space Flight Center in the USA. He is currently a Professor of Astronomy at the University of Southampton, UK. He works on multiwavelength studies of X-ray emitting binary systems both in the Magellanic Clouds and the Milky Way and is an extensive user of telescopes in South Africa & Chile. He is interested in the way different environments may affect stellar evolution processes.

Hazards in space! Will SumbandilaSAT survive?

deanne — Tue, 27 Sep 2011 17:00:21 +0200

Abstract: Satellites have to operate in a hostile space environment that poses numerous threats from natural space material and man-made space objects. The variability of the space weather environment and the proliferation of space debris constitute major hazards for spacecraft in Earth orbit.
SumbandilaSAT, South Africa’s micro-satellite, was built with Commercial-Off-the-Shelf (COTS) components and was launched in a bid to harness Earth observation applications for sustainable development. COTS components though cheaper, are more vulnerable to the effects of space weather than space-qualified components. Assessing the feasibility of this COTS-based approach by examining the in-orbit performance of SumbandilaSAT is therefore imperative to the development of future South African indigenous satellites.
I have modeled the environmental impositions on SumbandilaSAT expected during its operational lifetime with which I assessed the in-orbit risks due to natural space material. Its failure probability due to hypervelocity impacts, and the probability of collision with identified conjuncting space objects have also been estimated. The results are presented.

About the speaker: Cj Nwosa holds a bachelors (hons) in Astrophysics and Space Science from University of Nigeria/University of Cape Town. He recently handed in his Masters thesis titled "Orbital risk assessment for SumbandilaSat". His growing interest in Space Technology and its applications has driven him to be a member of the Space Generation Advisory Council, an international volunteer organisation representing young space enthusiasts to the UN Office for Outer Space Affairs, Space Agencies, and related entities. He has been involved in experimental rocketry, satellite orbit analysis, space weather, and planetary wave projects.

Investigating the stability of the South African Ionosphere in Support of the Square Kilometre Array bid

deanne — Tue, 27 Sep 2011 16:58:44 +0200

Abstract: The ionosphere, a region of ionised plasma extending 90-2000 km above the earth’s surface, plays an important role in radio astronomy. All trans-ionospheric radio signals, including those received from stellar sources, are modulated by the ionised plasma in the ionosphere and experience Faraday rotation, group delay, phase advance and rapid amplitude fading and phase shifts resulting from ionospheric irregularities in the form of small scale patches (bubbles) of increased/decreased electron density. A well characterised and stable ionosphere is subsequently an important criterion for ensuring quality radio astronomy observations from a sensitive radio telescope like the Square Kilometre Array (SKA).
Of particular concern for SA’s SKA hosting bid was the influence of the South Atlantic Magnetic Anomaly (SAMA) on the South African ionosphere. The SAMA, a region of low geomagnetic field strength located between South Africa and Southeast Brazil, extends eastward over southern Africa and experiences increased electromagnetic (EM) and Electrically Charged Energetic Particle Precipitation (ECEPP) radiation which would result in increased ionisation and conductivity of the upper atmosphere, possibly affecting the South African ionosphere.
To investigate the long-term stability of the South African ionosphere and possible affects thereon from increased SAMA ionisation and ECEPP radiation, two comprehensive studies were undertaken by SANSA. The studies utilised observations from ground-based ionosondes (vertically sounding HF radars), a network of scientific GPS receivers and satellite-based ECEPP measurements. The studies considered various parameters like diurnal, seasonal and solar cycle variations; geographic dependence; travelling ionospheric disturbances; correlation between scintillation and ECEPP. The studies concluded that the South African ionosphere is suitably stable for hosting a sensitive radio telescope like the SKA.

Profile: Dr Ben Opperman is a Space Physicist employed at SANSA Space Science (Hermanus) since 2002. His specific field of interest is ionospheric imaging and computerised ionospheric tomography by exploiting errors on radio signals from Global Navigation Satellite Systems (GNSS). He holds a BSc degree in Mathematics and Physics (Northwest University), BSc Honours and MSc degrees (Stellenbosch University) and a PhD in Physics (Rhodes University). His work experience includes five years at the Overberg Test range and Houwteq (1990-1995) on the Greensat satellite and seven years on the SUNSAT programme at Stellenbosch University (1995-2002). He’s presently involved in cubesat scientific experiments and investigating ionospheric dynamics across the African continent.

Tidal dwarf galaxies and the halo of the Milky Way

deanne — Tue, 27 Sep 2011 16:56:57 +0200

Abstract: The outer halo of our galaxy, the Milky Way, has 8 classical dwarf spheroidal galaxies with a few million stars each, in addition to the two much larger Magellanic galaxies and their associated stream. Here I try to incorporate recent observational data on the proper motions of these satellite galaxies, as well as their internal dynamics and the distribution of dark matter in the Milky Way to assess various formation scenarios for the Milky Way's evolution. I also compare with observations of other satellite systems and suggest a controversial resolution.

Speaker Bio: Garry Angus is a postdoc in the Astrophysics, Cosmology and Gravity Centre at the University of Cape Town. He did his undergraduate degree at the University of Aberdeen and his PhD at the University of St. Andrews, both in Scotland. Before arriving in Cape Town he was a postdoc at the University of Torino in Italy for 2 years. His research focus is testing the alternative theory of gravity Modified Newtonian Dynamics at all astrophysical scales using cosmological N-body simulations and the dynamics of stellar systems.

The Gravo-Magneto Instability: Accretion Outbursts in Young Stars and Planets

deanne — Tue, 27 Sep 2011 16:55:15 +0200

Abstract: FU Orionis stars are pre-main sequence stars that show outbursts where the optical brightness increases by up to 5 magnitudes on the timescale of a year. The outbursts are thought to be due to sudden transitions in the disc from gravitationally produced turbulence to magnetically produced. We explain these gravo-magneto outbursts on a state diagram that plots the accretion rate versus the disc surface density. We find a limit cycle that is analogous to the well known S-curve that has been applied to dwarf nova outbursts. The diagram provides a conceptual framework for understanding the nature of the outbursts that may occur in accretion discs of all scales, from circumplanetary to protoplanetary to AGN accretion discs.

Speaker Bio: Rebecca Martin is a Giacconi Fellow at the Space Telescope Science Institute in Baltimore, USA. Prior to working there, in 2009 she recieved her PhD in Theoretical Astrophysics, supervised by Jim Pringle, from Cambridge university, UK, where she also graduated with a masters and undergraduate degree in Mathematics.

Mass Distribution in Galaxies using Multi-Wavelength 3D Spectroscopy

deanne — Tue, 27 Sep 2011 16:43:55 +0200

Abstract: Spiral and dwarf galaxies are known to present an important mass discrepancy between their dynamical and visible masses. The commonly accepted hypothesis is to assume a more or less spherical halo of unseen matter in addition to the stars and gas. To study properly this mass discrepancy, different observational techniques at different wavelengths need to be combined in order to probe as best as possible the gravitational potential at all radii and different theoretical tools are necessary to sort out which distribution law represents best the dark matter component.

This Multi-wavelength approach will be illustrated by discussing the radio HI aperture synthesis observations of our Local Group neighbour, M31 (Andromeda) and the optical Ha Fabry-Perot interferometric observations of the SINGS sample of galaxies. As an example, it will be showed how important it is to model properly velocity perturbations, such as those produced by bars, before using the kinematics to derive the gravitational potential as a tracer of both the luminous and the dark matter components.

Speaker bio: Dr Claude Carignan did his PhD (1983) at Mount Stromlo and Siding Spring Observatory of the Australian National University where he pioneered the multi-component analysis technique of galaxy’s rotation curves using both radio HI and optical Ha kinematical data. He pursued his formation in HI radio synthesis work by a postdoctoral fellowship (1985) at the Rijksuniversiteit in Groningen using data from the Westerbork array. He then moved to the Université de Montréal in 1985 as a research associate and became full professor in 1998. During those years, he continued his studies of the mass distribution in galaxies using at radio wavelengths the Very Large Array (VLA), the Australia Telescope Compact Array (ATCA) and the Dominion Radio Astronomy Observatory (DRAO) and at optical wavelengths using Fabry-Perot Ha interferometry at the CFHT, ESO La Silla, WHT, OHP and OMM.

In 1998, he took over the directorship of the Observatoire du mont Mégantic Research Center and in 2002 became director of the Observatoire du mont Mégantic (OMM). More recently (2007), he became adjunct professor at the Université de Ouagadougou, in Burkina Faso, where he has set up an Astrophysics program and built a small Observatory for teaching purposes. At the end of 2009, he moved a telescope from Chili to Burkina Faso and the construction of the new research Observatory is under way and should be completed in 2012. Finally, on July 1st, he just started a South African Research Chair in Multi-wavelength Astronomy at UCT.

Space weather and Solar Activity influences mankind: Fact or fiction?

deanne — Thu, 12 May 2011 05:12:59 +0200

ABSTRACT: There are many doomsayers predicting dire consequences at
every solar maximum. The processes behind solar activity and the most
plausible effects on us will be discussed.

Gravitational lensing of the cosmic microwave background radiation

deanne — Fri, 06 May 2011 13:40:54 +0200

Abstract: In this presentation I describe the phenomenon of gravitational lensing of cosmic microwave background (CMB) photons by the large-scale mass distribution in the universe. I discuss the recent detection of the CMB lensing signal by the Atacama Cosmology Telescope, and outline prospects for utilising this signal to contrain cosmology with future CMB experiments. By analysing the statistical distortions of the CMB anisotropy pattern measured by these experiments we will be able to reconstruct maps of the projected mass distribution that will allow us to learn about neutrino masses, dark matter and dark energy properties.

Speaker bio: Kavilan completed a B.Sc.(Hons) in 1996 at the University of Cape Town, and an M.Sc. in 1998 at the University of Natal (Durban). After completing his PhD in 2002 at the University of Cambridge he worked as a postdoctoral researcher in the astrophysics department at the University of Oxford. Kavilan returned to South Africa in 2003 taking up a lectureship at the University of KwaZulu-Natal in the School of Mathematical Sciences, where he currently holds the position of associate professor. Kavilan is a scientific board member of the Atacama Cosmology Telescope project and won the South African Institute of Physics silver jubilee medal in 2007. Kavilan's research interest is in the area of cosmology and involves confronting cosmological theories with observational data, in particular observations of the cosmic microwave background and large-scale structure.

Testing the equivalence principle

deanne — Tue, 26 Apr 2011 14:55:01 +0200

Abstract: The equivalence principle is at the heart of the geometrisation of gravity and one of the building block of general relativity. It is tested to a high accuracy in the Solar system but poorly on astrophysical and cosmological scales. This seminar will summarized the role of the equivalence principle and its tests in the Solar system. It will then discuss the possibility to test it with the constant of nature and describe the various constraints that have been obtained from the comparison of atomic clocks in the lab to big-bang nucleosynthesis.

Speaker: Jean-Philippe Uzan has obtained its PhD from Paris XI university in 1998 and was a student of Nathalie Deruelle. After a postdoc at Geneva university he was hired by the CNRS, where he is now directeur de recherche and works at the Institut d'Astrophysique de Paris. His main works concern the tests of the underlying hypothesis of the standard cosmological model. It includes study of the topology of the universe, tests of general relativity and tests of the Copernican principle. He has also worked on scalar-tensor theories, as well as on inflation and CMB theory, focusing mostly on non-Gaussianity. He has been teaching physics at the Ecole des Mines de Paris and Cosmology at the Ecole Normale Superieure de Paris. He has co-authored the monography "Primordial cosmology" (OUP) and written several popular science books, among which books for children.

The Dark Universe

deanne — Mon, 18 Apr 2011 10:31:15 +0200

Abstract: The current model of the Universe, based on Einstein's General Relativity and the Standard Model of Particle Physics, is very successful in many ways - but there are deep puzzles at its foundations. The galaxies that we observe cannot grow fast enough and cannot be held together - unless there is a new form of matter, which so far has not been detected on Earth, called "Dark Matter". The accelerating expansion of the Universe cannot be explained by Dark Matter - and so we need another form of matter, called "Dark Energy". For Dark Matter, the particle theorists at least have some possible particles. But for Dark Energy, there is still no satisfactory model. We live in a Dark Universe that we do not understand properly. Or perhaps there is something else wrong with our model of the Universe. Maybe the Universe is not as smooth as we think. And maybe Einstein's theory breaks down when we go beyond the solar system and the Milky Way.

Speaker bio: ROY MAARTENS holds an SKA Research Chair at UWC. He studied at UCT and got his PhD with George Ellis. Then he worked at Wits University in the eighties, before moving to the UK in the nineties, where he was Director of the Institute of Cosmology & Gravitation, Portsmouth University. Roy works on dark energy - looking at various theories for dark energy, and seeing how they can be tested by observations. He also looks at modifications of Einstein's theory and at inhomogeneous models - as alternatives to dark energy.

High Speed Astronomy

deanne — Wed, 06 Apr 2011 03:37:50 +0200

Abstract: Not everything in the sky changes on astronomical time scales (millions to billions of years). Sometimes it is possible to observe many cycles of change within one night. As an example I will describe the rapid periodic and quasi-periodic variations that short period mass-transferring binary stars (cataclysmic variables and X-Ray binaries) show in optical and X-Ray observations.

Brian Warner obtained his Ph.D. Astronomy from University College, London. He also has a D.Sc. (University of London), a D.Sc. (University of Oxford) and an honorary Doctorate from the University of Cape Town, where he was head of the Astronomy Department from 1972 to 2004. He began publishing papers in "The Moon" (the journal of the Lunar Section of the British Astronomical Association) while still in high school. Since then, he has written over 400 papers and numerous books on astronomy, history, botany and poetry. His book entitled "Cataclysmic Variable Stars" is cited in almost every paper on the subject. His research interests include Cataclysmic Variable stars, pulsating degenerate stars and the history of astronomy.

Dusty Plasmas in Space and in the Laboratory

deanne — Tue, 22 Mar 2011 13:14:36 +0200

Abstract: I will give an informative overview lecture on dusty plasmas, defining a "dusty" plasma, and mentioning where these plasmas occur in space environments. I will talk about two fundamental wave modes that propagate in a dusty plasma such as the dust-acoustic wave and the dust-ion-acoustic wave. I will then go on to discuss the experimental observation of the dust-acoustic wave and how the observed frequency matches with the theoretical dispersion relation for the mode. I will also discuss interesting observations of plasma crystal formation in strongly coupled dusty plasmas. I will then discuss some results from a current research topic of mine where I will discuss existence domains of large amplitude solitons in a dusty plasma based on a model composed of both positive and negative dust, non-thermal ions and Boltzmann electrons.

Speaker bio: My undergraduate (BSc) and Honours degrees I obtained from the University of Natal in Pietermaritzburg. I obtained an MSc in theoretical Plasma Physics from the University of Durban-Westville where I was Associate Lecturer in the Physics Department from 2000-2002. While working as a research assistant at the Hermanus Magnetic Observatory, I obtained a PhD in theoretical plasma physics from the University of KwaZulu-Natal in 2006. I am now a Research Physicist at the Hermanus Magnetic Observatory and my current area of research is theoretical plasma physics: I use plasma fluid theory to investigate the existence of coherent nonlinear wave structures such as solitons and double layers in dusty and space plasmas.

The IAC and Space Activities in South Africa

deanne — Wed, 16 Mar 2011 08:06:02 +0200

Abstract: This year, the International Astronautical Congress (IAC) will be held in Africa for the first time ever, along with various other events to be held in Cape Town during September and October - a series of events sure to be the highlight of the year. Naturally, this is a unique opportunity for interested individuals and organisations to gain international exposure, but also means that increased attention is being paid to the emerging South African space sector. During the presentation, I will take a step back to give a brief summary of space activities in South Africa - the people, organisations and projects aimed at making South Africa a key player in space - and why increased involvement in space is important. I will also highlight several ways by which students can become more active in the space arena and in events to be held during the time of the IAC.

Speaker bio: I completed my BSc. in Physics and Applied Maths at the Nelson Mandela Metropolitan University in Port Elizabeth in 2008. In 2009, I did a BSc. Hons. through the NASSP. I'm currently doing the dissertation component of my NASSP MSc., which is concerned with developing the control software for the Alan Cousins Telescope - a fully robotic and automatic telescope of the South African Astronomical Observatory in Sutherland. Although my formal education has been predominantly astronomically oriented, I'm very interested in space science and technology. Through my work, I hope to highlight the similarities between astronomy and space science rather than the differences.

"The Current State of the Earth's Magnetic Field"

deanne — Tue, 08 Mar 2011 15:40:36 +0200

Frontiers in Classical Gravity

deanne — Mon, 28 Feb 2011 11:54:31 +0200

The past decade has brought about many exciting developments in the field of General Relativity. Large scale experiments make the direct detection of gravitational waves likely within the next decade, and numerical methods have allowed researches to probe strong, dynamical, nonlinear gravity for the first time. I will give an overview of the current state of modern research in classical General Relativity, aimed at informing students about possible research directions relating to this field.

Speaker bio: Aaron did his undergraduate studies at the University of New Mexico, where he received a bachelor's degree in Astrophysics. He is currently pursuing his PhD in Physics at Caltech, where he is advised by Yanbei Chen. He is also doing research with Jeandrew Brink at NITHEP in Stellenbosch.