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BEGIN:VEVENT
SUMMARY:Constraining Viewing Geometries of Pulsars With Single-Peaked Gamm
 a-ray Profiles Using A Multiwavelength Approach
DTSTART;VALUE=DATE-TIME:20110713T103000Z
DTEND;VALUE=DATE-TIME:20110713T104500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4868@events.saip.org.za
DESCRIPTION:Speakers: Albertus Seyffert (North-West University)\nSince the
  launch of the Large Area Telescope (LAT) on board the Fermi spacecraft in
  June 2008\, the number of observed gamma-ray pulsars has increased dramat
 ically. A large number of these are also observed at radio frequencies. We
 ltevrede et al. (2010) derived constraints on the viewing geometries of 6 
 gamma-ray pulsars exhibiting single-peaked gamma-ray profiles using high-q
 uality radio polarization data. We obtain independent constraints on the v
 iewing geometries by using a geometric emission code to model the Fermi-LA
 T and radio light curves. We find fits for the magnetic inclination and ob
 server angles by searching the solution space by eye. Our results are gene
 rally consistent with those obtained by Weltevrede et al. (2010)\, althoug
 h we do find differences in some cases. We will indicate how the gamma-ray
  and radio pulse shapes as well as their relative phase lags lead to const
 raints in the solution space. A more rigorous approach\, the Monte Carlo M
 arkov Chain technique\, is able to statistically find best-fit light curve
 s in addition to constraining several model parameters and estimating erro
 rs on these.\n\nhttps://events.saip.org.za/event/7/contributions/4868/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4868/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Solar-cycle dependent relationship between cosmic-ray intensity an
 d the heliospheric current sheet tilt angle
DTSTART;VALUE=DATE-TIME:20110715T093000Z
DTEND;VALUE=DATE-TIME:20110715T094500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4875@events.saip.org.za
DESCRIPTION:Speakers: KATLEGO MOLOTO (NORTH WEST UNIVERSITY)\nWe investiga
 te cosmic-ray intensities as measured by neutron monitors as function of t
 he corresponding heliospheric current sheet tilt angle. Three solar cycles
  with three changes in solar magnetic polarity are examined. The results a
 re compared to predictions of cosmic-ray modulation models that include dr
 ift effects. The intensity-tilt plots produce open loops with clockwise ro
 tations for solar cycles 21 and 23 and with anticlockwise rotation for sol
 ar cycle 22\, as predicted by drift models. However\, the observed intensi
 ty-tilt loops for cycles 21 and 23 are larger than the loop for cycle 22 c
 ontrary to the drift model predictions. To explain this difference we use 
 the time dependence of the tilt angle and show that the loops then become 
 very similar. We show that from this renormalization\, the approximate tim
 e it takes for particles to travel from the termination shock to Earth can
  be estimated\, and that the time is consistent with model predictions.\n\
 nhttps://events.saip.org.za/event/7/contributions/4875/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4875/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The neutron superfluid in the interior of neutron stars.
DTSTART;VALUE=DATE-TIME:20110714T070000Z
DTEND;VALUE=DATE-TIME:20110714T071500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4885@events.saip.org.za
DESCRIPTION:Speakers: Garreth Kemp (University of Johannesburg)\nIn his wo
 rk on superfluid helium\, Feynman gave both qualitative and quantitative d
 escriptions of the excitation spectrum of superfluid helium. I briefly rev
 iew Feynman's approach to superfluid helium and assess the applicability o
 f this theory to neutron star interiors.\n\nhttps://events.saip.org.za/eve
 nt/7/contributions/4885/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4885/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Campaign for Vicarious Calibration of SumbandilaSat in Argentina
DTSTART;VALUE=DATE-TIME:20110715T063000Z
DTEND;VALUE=DATE-TIME:20110715T064500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4908@events.saip.org.za
DESCRIPTION:Speakers: Lufuno Vhengani (CSIR)\nThe importance of calibratin
 g satellite imagers has been explained in literature such as K Arai (2007)
  and K J Thome (2001). Calibration of satellite sensors (imagers) is cruci
 al for data consistency\, reliability and comparability. To perform a mean
 ingful analysis of a satellite image\, the Digital Numbers (DNs) of the im
 age are first converted to absolute radiance by using the sensor-specific 
 radiometric calibration coefficients. Satellite imagers are calibrated pre
 -launch and for continuous assessment\, they are also calibrated post-laun
 ch. Various post-launch techniques exist including cross-sensor\, solar\, 
 lunar and vicarious calibration. Vicarious calibration relies on in-situ m
 easurements of surface reflectance and atmospheric transmittance to estima
 te Top-Of-Atmosphere (TOA) spectral radiance. A vicarious calibration fiel
 d campaign was executed in Argentina to support monitoring of the radiomet
 ric response of the multispectral imager aboard SumbandilaSat. Results obt
 ained using two Radiative Transfer Codes (RTCs) MODTRAN and 6S are present
 ed.\n\nhttps://events.saip.org.za/event/7/contributions/4908/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4908/
END:VEVENT
BEGIN:VEVENT
SUMMARY:ThunderKAT: The MeerKAT Large Survey Project for Radio Transients
DTSTART;VALUE=DATE-TIME:20110713T094500Z
DTEND;VALUE=DATE-TIME:20110713T100000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4909@events.saip.org.za
DESCRIPTION:Speakers: Patrick Woudt (Department of Astronomy\, University 
 of Cape Town)\nThunderKAT is one of ten accepted MeerKAT Large Survey Proj
 ects. \nThunderKAT will study all aspects of transient radio emission asso
 ciated with accretion and explosive events. Through a comprehensive and co
 mplementary programme of monitoring Galactic synchrotron transients (acros
 s a range of compact accretors and a range of other explosive phenomena) a
 nd exploring distinct populations of extragalactic synchrotron transients 
 (microquasars\, supernovae (SNe) and possibly yet unknown transient phenom
 ena) we will revolutionise our understanding of the dynamic and explosive 
 transient radio sky. \nWe will give an overview of ThunderKAT and discuss 
 the prospects of studying the transient sky with KAT-7.\n\nhttps://events.
 saip.org.za/event/7/contributions/4909/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4909/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Modeling X-ray Emission and the SED of the Binary Radio Pulsar AE 
 Aquarii
DTSTART;VALUE=DATE-TIME:20110713T121500Z
DTEND;VALUE=DATE-TIME:20110713T123000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4914@events.saip.org.za
DESCRIPTION:Speakers: Bosco Oruru (University of the Free State)\nThe high
 ly transient novalike variable AE Aqr is perhaps an ideal laboratory to st
 udy accretion related astrophysical fluid dynamics. It consists of a fast 
 spinning highly magnetic white dwarf (WD) orbiting\, and accreting mass\, 
 from a low-mass main sequence companion. The system emits\, and has been d
 etected in almost all wavelengths. AE Aqr is in a propeller state\, and mo
 st of its emission properties are associated with the turbulent interactio
 n between the accretion flow and the fast rotating magnetosphere of the WD
 . We have analysed its X-ray spectra using contemporaneous Chandra and Swi
 ft X-ray data. The results of this study show that the X-ray emission has 
 both thermal and non-thermal characteristics. The thermal X-ray emission i
 s modeled to be the result of bremsstrahlung emission of heated mass outfl
 ow above the polar caps\, whereas the non-thermal X-ray emission is the re
 sult of synchrotron radiation of accelerated electrons outside the light c
 ylinder radius of the WD. In this paper\, some of the results\, based on t
 he constraints of the proposed thermal and non-thermal emission mechanisms
 \, will be presented.\n\nhttps://events.saip.org.za/event/7/contributions/
 4914/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4914/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Astrophysics Poster Blitz
DTSTART;VALUE=DATE-TIME:20110713T114500Z
DTEND;VALUE=DATE-TIME:20110713T121500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4924@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/7/contributions/4924/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4924/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Space Physics Poster Blitz
DTSTART;VALUE=DATE-TIME:20110714T114500Z
DTEND;VALUE=DATE-TIME:20110714T121500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4925@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/7/contributions/4925/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4925/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Genetic algorithms in astronomy and astrophysics
DTSTART;VALUE=DATE-TIME:20110714T093000Z
DTEND;VALUE=DATE-TIME:20110714T094500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4977@events.saip.org.za
DESCRIPTION:Speakers: Vinesh Rajpaul (UCT)\nGenetic algorithms form a clas
 s of search heuristics that incorporate\, in a computational setting\, the
  biological notion of evolution by means of mutation and natural selection
 . Compared to more conventional search and optimisation techniques\, genet
 ic algorithms are very easy to implement and they tend to be extremely rob
 ust and versatile. Although already ubiquitous in fields such as computer 
 science\, engineering and artificial intelligence\, genetic algorithms hav
 e not yet been widely adopted in the physical sciences.\n\nI provide a ver
 y brief introduction to genetic algorithms and outline their relevance to 
 a number of diverse problems in astronomy and astrophysics\, from stellar 
 structure modelling and astroseismological analyses to robotic telescope s
 cheduling. In particular I discuss a difficult optimisation problem in gra
 vitational microlensing analysis for which it is hoped that genetic algori
 thms might facilitate an efficient exploration of an enormous parameter sp
 ace.\n\nhttps://events.saip.org.za/event/7/contributions/4977/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4977/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Properties of the Interstellar medium in nearby galaxies
DTSTART;VALUE=DATE-TIME:20110714T100000Z
DTEND;VALUE=DATE-TIME:20110714T101500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-4984@events.saip.org.za
DESCRIPTION:Speakers: Roger IANJAMASIMANANA (University of Cape Town)\nWe 
 use the HI velocity profiles of The HI Nearby Galaxy Survey (THINGS) to st
 udy the phase structure of the ISM and its relation to galaxy properties a
 nd morphology. To construct high S/N profiles\, we use a method analogous 
 to the stacking method sometimes used in high redshift HI observations. We
  call these high S/N profiles super profiles. By decomposing the super pro
 files into Gaussian components\, we found broad and narrow components whic
 h are evidence of the presence of Cold Neutral Medium (CNM) and Warm Neutr
 al Medium (WNM). We also derive radial super profiles of the THINGS galaxi
 es and we found some correspondance between the shapes of the super profil
 es and their location within the galaxies. We found that the narrrow compo
 nents dominate inside the optical radius r25. We also analyze the shapes o
 f the super profiles in low\, moderate and high star formation rate (SFR) 
 regions and we found that the narrow component dominates in high SFR regio
 ns. The profiles also tend to be more asymmetric and broader in high SFR r
 egions.\n\nhttps://events.saip.org.za/event/7/contributions/4984/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/4984/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NON-SPECIALIST: Cosmic-ray modulation studies – why Parker neede
 d Dirac and Kolmogorov
DTSTART;VALUE=DATE-TIME:20110715T090000Z
DTEND;VALUE=DATE-TIME:20110715T093000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5053@events.saip.org.za
DESCRIPTION:Speakers: Renier Burger (North-West University)\nIn 1958\, Eug
 ene Parker predicted that the outer parts of the Sun's atmosphere\, the so
 lar corona\, must be expanding in the form of a supersonic solar wind. Thi
 s was confirmed by the Mariner 2 spacecraft in 1962. On 16 December 2004\,
  the Voyager 1 spacecraft crossed the heliospheric termination shock\, whe
 re the flow becomes subsonic\, and began exploring the heliosheath. In Aug
 ust 2007\, Voyager 2 also crossed the termination shock. The plasma proper
 ties of the heliosheath differ greatly from those of the heliosphere insid
 e of the termination shock and particle transport beyond the termination s
 hock is not yet fully understood. Different approximations of the cosmic-r
 ay transport equation\, originally derived by Parker in 1965\, have been u
 sed for decades to study cosmic-ray modulation in the region inside of the
  termination shock\, the focus of this presentation. Cosmic rays that reac
 h Earth are subject to diffusion\, convection\, adiabatic energy changes\,
  and gradient- and curvature drift due to the non-uniform heliospheric mag
 netic field. The consequence is that cosmic-ray intensities at Earth are l
 ower than the interstellar value and is referred to as modulation. The tur
 bulent heliospheric magnetic field is frozen into the supersonic solar win
 d. Inside of the termination shock the two hemispheres with oppositely dir
 ected magnetic field is separated by the so-called wavy neutral sheet\, ac
 ross which the magnetic field changes direction. We discuss how modulation
  studies have progressed from using simple spherically symmetric solutions
  of Parker's transport equation\, to the current situation where in order 
 to properly account for diffusion and drift\, complex turbulence transport
  models are required as well as detailed knowledge of the form of turbulen
 ce energy spectra\, the latter which include the so-called inertial range 
 derived by Kolmogorov in 1941. Turning to plasma physics\, we show that wh
 at appear to be two very different kinds of drift motion\, along and away 
 from the neutral sheet\, actually follow from the standard expression for 
 gradient- and curvature drift\, provided that the particle distribution is
  nearly isotropic. In the course of this derivation one is confronted by a
  Dirac delta function that must be replaced by something physically accept
 able without changing the physics involved. We also discuss why we can stu
 dy the drift coefficient which determines drift velocity\, while using a u
 niform background magnetic field that obviously does not cause large-scale
  drifts.\n\nhttps://events.saip.org.za/event/7/contributions/5053/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5053/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lightning induced whistler waves as a cause of electron precipitat
 ion
DTSTART;VALUE=DATE-TIME:20110715T100000Z
DTEND;VALUE=DATE-TIME:20110715T101500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5054@events.saip.org.za
DESCRIPTION:Speakers: Marlie van Zyl (University of KwaZulu-Natal)\nLightn
 ing induced whistler waves are one of the primary causes of energetic elec
 tron loss from the Earth's radiation belts. This is mainly due to the pitc
 h angle scattering of the particles by whistler mode waves\, leading to pr
 ecipitation. The detailed spatial and temporal influence of lightning on p
 recipitation losses is\, however\, not well known. The World Wide Lightnin
 g Location Network (WWLLN) gives continuous global lightning coverage with
  good time resolution. Since the detection efficiency of WWLLN is relative
 ly low\, it was compared to LIS/OTD data. However\, whereas WWLLN records 
 strokes\, LIS/OTD record flashes. Therefore the flash multiplicity has to 
 be taken into account. By incorporating multiplicity and lightning stroke 
 orientation to the WWLLN global lightning distribution and then transformi
 ng the resulting data to geomagnetic(MAG)coordinates\, the average VLF pow
 er that is radiated into the ionosphere can be estimated. This can be used
  to determine the energy and the spectrum of the waves that go on to enter
  the magnetosphere. Hence the precipitation losses due to whistler mode wa
 ves can be studied.\n\nhttps://events.saip.org.za/event/7/contributions/50
 54/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5054/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pulsating B stars in the LMC
DTSTART;VALUE=DATE-TIME:20110713T130000Z
DTEND;VALUE=DATE-TIME:20110713T131500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5065@events.saip.org.za
DESCRIPTION:Speakers: Christian Engelbrecht (University of Johannesburg)\n
 Pigulski and Kolaczkowski (2002\, A&A 388\, 88) announced the first discov
 ery of Beta Cephei (BCep) pulsators in the LMC. This was a remarkable disc
 overy\, since theoretical analyses of pulsational stability had previously
  predicted that early B main-sequence stars with metallicities lower than 
 Z = 0.01 should not pulsate at all (e.g. Pamyatnykh 1999\, Acta Astron 49\
 , 199). Following this announcement\, and announcements of 92 BCep candida
 tes in the LMC by Kolaczkowski and Pigulski (2006\, MemSAIt. 77\, 336)\, m
 ore detailed studies adopting a variety of opacity calculations and metal 
 mixtures indicated that BCep pulsations could be explained in low-metallic
 ity environments after all (Miglio et al. 2007\, MNRAS 375\, L21\; Miglio 
 et al. 2007\, Com.Ast. 151\, 48\; Zdravkov and Pamyatnykh 2008\, J.Phys.Co
 nf.Ser. 118\, 012079). In order to ascertain the nature of these pulsation
 s\, multi-colour photometry of sufficient precision is required. \n\nWe ha
 ve obtained 4 weeks of UBVI photometry on two fields in the LMC that surro
 und stars which have been identified as strong Beta Cephei candidates from
  OGLE data. We report on the results of this photometric campaign.\n\nhttp
 s://events.saip.org.za/event/7/contributions/5065/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5065/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Searching for signatures of nearby sources of cosmic rays in their
  local chemical composition
DTSTART;VALUE=DATE-TIME:20110714T061500Z
DTEND;VALUE=DATE-TIME:20110714T063000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5066@events.saip.org.za
DESCRIPTION:Speakers: Driaan Bisschoff (North-West University)\nThe direct
  evidence for the acceleration of hadronic cosmic rays at supernova remnan
 ts underlined the need for a 3D time dependent treatment of the propagatio
 n of Galactic Cosmic Rays (CRs). Full 3D time dependent calculations of th
 e propagation of CRs have shown that if CRs indeed originate from supernov
 a remnants\, transient point-like sources\, the flux of the CR primary com
 ponent measured at Earth depends strongly on the local source history\, wh
 ereas the secondary component shows only little or no variations due to ne
 arby sources. The most widely used steady state\, rotational symmetric mod
 els (2D) of CR propagation cannot take into account the local source histo
 ry\, but rather mimic source histories that result in the same local CR fl
 ux as the smeared-out sources assumed in 2D models and do not necessarily 
 coincide with the real local source history. Using a steady state\, rotati
 onal symmetric model for a parameter study\, one may expect different best
  fit values looking at the primary and secondary CR components separately\
 , as it is unlikely that the source history mimicked by the 2D models coin
 cide with the real local source history. \nWe adapted the 2D version of th
 e GALPROP code to a cluster environment and perform parameter studies comp
 aring CR spectra with mainly primary and secondary CR data separately. Fir
 st results of these studies will be presented and recommendations for furt
 her such studies will be given.\n\nhttps://events.saip.org.za/event/7/cont
 ributions/5066/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5066/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eclipsing Contact Binary Stars – Period Analysis using SuperWASP
  data
DTSTART;VALUE=DATE-TIME:20110713T123000Z
DTEND;VALUE=DATE-TIME:20110713T124500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5088@events.saip.org.za
DESCRIPTION:Speakers: Patricia Skelton (UNISA)\nSome eclipsing contact bin
 ary stars of the W UMa-type are known to undergo changes in orbital period
 .  These changes can be as a result of the light travel time effect if the
  contact binary is a member of a multiple stellar system or due to some in
 trinsic phenomena that are poorly understood at this stage.  Analysing sys
 tems that appear to be undergoing changes in orbital period may shed some 
 light on the important physical processes that occur in close binary syste
 ms.  Pilecki et al. (2007) searched through the All Sky Automated Survey (
 ASAS) database for semi-detached and contact binary systems with high peri
 od change rates.  They present 31 interacting binaries whose periods eithe
 r increased (10) or decreased (21) in a five year interval of observations
 .  Using data from the Wide Angle Search for Planets (SuperWASP) project\,
  it has been possible to do period analyses using O – C diagrams which p
 rovide a more reliable measure of period change.  The results of the analy
 ses will be presented.\n\nhttps://events.saip.org.za/event/7/contributions
 /5088/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5088/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The unusual Seyfert Markarian 926 - a link to the LINERs?
DTSTART;VALUE=DATE-TIME:20110715T103000Z
DTEND;VALUE=DATE-TIME:20110715T104500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5090@events.saip.org.za
DESCRIPTION:Speakers: Hartmut Winkler (Dept. Physics\, University of Johan
 nesburg)\nMarkarian 926 (= MCG-2-58-22) is one of the earliest Seyfert gal
 axies identified. At discovery it was one of the most luminous nearby acti
 ve galactic nuclei (AGN)\, with strong\, wide broad lines. In the late 198
 0's it started fading\, eventually settling at barely ~10% of its recorded
  peak luminosity. The luminosity decrease was accompanied by significant s
 pectral changes\, with the broad-line component now much weaker and highly
  asymmetrical. Low ionisation narrow lines\, however\, are now unusually s
 trong\, more typical of the AGN class referred to as LINERs rather than a 
 Seyfert. This peculiar low-luminosity phase spectum has remained relativel
 y constant over the last decade. The paper will discuss the spectral and o
 ther characteristics of Markarian 926 and compare these to standard Seyfer
 t models. It will furthermore investigate Markarian 926's relationship to 
 the LINERs\, and whether SALT observations of this object could shed light
  on the interrelationship between Seyferts and LINERs.\n\nhttps://events.s
 aip.org.za/event/7/contributions/5090/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5090/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Photometric solutions of eclipsing binary stars
DTSTART;VALUE=DATE-TIME:20110713T124500Z
DTEND;VALUE=DATE-TIME:20110713T130000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5091@events.saip.org.za
DESCRIPTION:Speakers: Derck Smits (University of SA)\nKazarovets et al. (1
 999) gave General Catalogue of Variable Star (GCVS) designations to 3157 v
 ariable stars that had been identified from observations made using the Hi
 pparcos satellite.  The variables were classified into standard GCVS categ
 ories according to their photometric light curves\, but no other parameter
 s of the variables were documented.  V-band photometric data for many of t
 he Hipparcos-identified eclipsing binaries can be found in the All Sky Aut
 omated Survey (ASAS) and Wide Angle Search for Planets (SuperWASP) databas
 es.  In several cases the ASAS classifications\, which were done semi-auto
 matically and without cross referencing other databases\, differ from thos
 e presented in IBVS 4659.  Using the ASAS and/or SuperWASP data\, the clas
 sifications are being checked\, orbital periods are being determined and\,
  where possible\, photometric solutions to the light curves are being obta
 ined.  This talk will present the results of this investigation.\n\nhttps:
 //events.saip.org.za/event/7/contributions/5091/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5091/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Numerical modelling of stellar winds for supernova progenitors
DTSTART;VALUE=DATE-TIME:20110714T063000Z
DTEND;VALUE=DATE-TIME:20110714T064500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5092@events.saip.org.za
DESCRIPTION:Speakers: Stefanus Petrus van den Heever (North West Universit
 y)\nA two-dimensional hydrodynamic numerical model is extended and applied
  to simulate the interaction between stellar winds and the interstellar me
 dium (ISM). In particular\, the stellar wind evolution of O-and B-type sta
 rs is calculated. First\, the evolution of a stellar wind into the ISM and
  also a more dense molecular cloud are considered for the case of no relat
 ive motion between the star and the ISM. This interaction results in a cav
 ity being blown into the ISM. Of importance is the boundary radius (astrop
 ause) and the location where the outflow speed decreases from supersonic t
 o subsonic speeds\, the termination shock. Parameters like ISM density\, o
 utflow speed and mass-loss rate were varied to study the difference in the
  computed astropause (AP) and termination shock (TS) radii. The evolution 
 of these structures is presented to a simulation time of 1 My. The evoluti
 on of stellar winds into the ISM including relative motion is also conside
 red. It is shown that the positions of the TS and AP are dependent on the 
 mass-loss rate and stellar wind outflow speed of the star and the interste
 llar medium density and relative speed. When these massive stars reach the
  end of their life\, they end their life in a supernova explosion. The exp
 losion results in a blast wave moving outward\, called the forward shock (
 FS) and a reverse shock (RS) also forms which moves inward. Ferreira and d
 e Jager 2008 simulated supernova remnant (SNR) evolution for the case of e
 volution into the undisturbed ISM (no cavity). The evolution of SNR is sim
 ulated taking also into account the pre-existing cavity blown out by the s
 tellar winds of these massive stars. The results of this study showed that
  the evolution of the SNR is definitely influenced by the presence of a st
 ellar wind cavity even if the cavity is only a few pc in extent.\n\nhttps:
 //events.saip.org.za/event/7/contributions/5092/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5092/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Brightest Cluster Galaxies - Ages and metallicities of stellar pop
 ulations
DTSTART;VALUE=DATE-TIME:20110714T103000Z
DTEND;VALUE=DATE-TIME:20110714T104500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5100@events.saip.org.za
DESCRIPTION:Speakers: Viljoen Danièl (North-West University)\nThe aim of 
 this project is to study the stellar populations\, and thereby evolution a
 nd star formation histories of brightest cluster galaxies (BCGs). In parti
 cular\, I will determine if a Single Stellar Populations (SSP) or Composit
 e Stellar Populations (CSP) provides the most significant fit for the BCGs
  using high signal-to-noise ratio (S/N)\, long-slit spectra\, obtained on 
 the Gemini and WHT telescopes. By using the ULySS software package\, the d
 ata will be fitted against the Pegase. HR and Vazdekis/Miles stellar popul
 ation models to simultaneously derive the SSP equivalent ages and metallic
 ities of the BCGs. Furthermore the stellar populations will be decomposed 
 into two or more components\, and the chi square (χ2) value for each comp
 onent is used to determine whether a SSP or CSP represents the BCGs most a
 ccurately. We find that both young and old stars are present in the stella
 r populations of these BCGs\, and those BCGs\, therefore show surprisingly
  diverse star formation histories.\n\nhttps://events.saip.org.za/event/7/c
 ontributions/5100/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5100/
END:VEVENT
BEGIN:VEVENT
SUMMARY:An African VLBI Network of Radio Telescopes
DTSTART;VALUE=DATE-TIME:20110713T093000Z
DTEND;VALUE=DATE-TIME:20110713T094500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5134@events.saip.org.za
DESCRIPTION:Speakers: Michael Gaylard (HartRAO)\nThe advent of internation
 al wideband communication by optical fibre has produced a revolution in co
 mmunications and the use of the internet.  Many African countries are now 
 connected to undersea fibre linking them to other African countries and to
  other continents.  Previously international communication was by microwav
 e links through geostationary satellites.  These are becoming redundant in
  some countries as optical fibre takes over\, as this provides 1000 times 
 the bandwidth of the satellite links.\n\nIn the 1970's and 1980's some two
  dozen large (30m diameter class) antennas were built in various African c
 ountries to provide the satellite links.  As these antennas become redunda
 nt\, the possibility exists to convert them for radio astronomy at a cost 
 of roughly one tenth that of a new antenna of similar size.  \n\nHartRAO a
 nd the SA SKA Project have started exploring this possibility with some of
  the African countries.\n\nhttps://events.saip.org.za/event/7/contribution
 s/5134/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5134/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the shape of rotating stars.
DTSTART;VALUE=DATE-TIME:20110713T131500Z
DTEND;VALUE=DATE-TIME:20110713T133000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5146@events.saip.org.za
DESCRIPTION:Speakers: Peter Nicol (University of Johannesburg)\nI adapt a 
 recent work by Zahn et al. on the shape of rapidly rotating stars to explo
 re the degree of oblateness for uniform\, differential and shellular rotat
 ion of the star. I also discuss the relation of these results to the class
 ical Roche limit.\n\nhttps://events.saip.org.za/event/7/contributions/5146
 /
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5146/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Theoretical derivation of an equation for planetary distances from
  the sun
DTSTART;VALUE=DATE-TIME:20110714T090000Z
DTEND;VALUE=DATE-TIME:20110714T091500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5147@events.saip.org.za
DESCRIPTION:Speakers: Pieter Wagener (Dept Physics\, NMMU)\nApplying the q
 uantisation of action variables to a theory of gravitation one derives dis
 crete values for planetary distances from the sun. The calculated values a
 gree with the observed values of all the planets. The derived equation als
 o applies to the exoplanets. The application is similar to that of the Wil
 son-Sommerfeld rule for atomic orbits.\n\nhttps://events.saip.org.za/event
 /7/contributions/5147/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5147/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stellar perturbation via Lie derivatives.
DTSTART;VALUE=DATE-TIME:20110714T091500Z
DTEND;VALUE=DATE-TIME:20110714T093000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5157@events.saip.org.za
DESCRIPTION:Speakers: Fabio Frescura (U Witwatersrand)\nPerturbation theor
 y uses Lagrangian techniques that require vector fields to be compared at 
 finitely separated points. This method can be generalised to the strong gr
 avitational field regime in one of two ways\, using either covariant or Li
 e derivatives. In this paper\, I argue that those methods based on the Lie
  derivative are more useful. The Lie derivative provides a clear picture o
 f how the deformation of the fluid flow takes place. It also provides a na
 tural way to discuss large perturbations. I apply this method to some elem
 entary stability problems in the study of stellar structure.\n\nhttps://ev
 ents.saip.org.za/event/7/contributions/5157/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5157/
END:VEVENT
BEGIN:VEVENT
SUMMARY:CMB Tensor Anisotropies in f(R) Gravity
DTSTART;VALUE=DATE-TIME:20110714T060000Z
DTEND;VALUE=DATE-TIME:20110714T061500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5166@events.saip.org.za
DESCRIPTION:Speakers: Hassan Bourhrous (University of Cape Town)\nThe cosm
 ic microwave background (CMB) carries information from the last scattering
  surface that puts constraints on the multitude of proposed cosmological m
 odels and the gravity theories they are based on. Amongst such theories ar
 e the f(R) theories of gravity which have become an interesting endeavour 
 to correct for the degeneracies of the concordance model.\nWe present a de
 scription of CMB anisotropies generated by tensor perturbations in f(R) th
 eories of gravity. The power spectra of the observables TT and EE in the s
 pecial case of f(R)=Rn are computed using a modified version of CAMB.\n\nh
 ttps://events.saip.org.za/event/7/contributions/5166/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5166/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pc3 pulsations during low density events
DTSTART;VALUE=DATE-TIME:20110715T071500Z
DTEND;VALUE=DATE-TIME:20110715T073000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5190@events.saip.org.za
DESCRIPTION:Speakers: Stefan Lotz (SANSA: Rhodes University)\nWe study the
  generation of Pc3 geomagnetic pulsations (22 – 100 mHz) measured at Tih
 any\, Hungary during intervals of very low solar wind (SW) proton density 
 (low density events - LDE’s) when Np ~ 1/cc. We know the main SW based d
 rivers of Pc3's are SW velocity and interplanetary magnetic field (IMF) di
 rection. However\, it is observed that under very low SW density pulsation
  activity measured on the ground is paused\, regardless of otherwise favou
 rable conditions. A simple statistical study is performed to show the depe
 ndence of pulsation activity on Np\, and we estimate a threshold Np\, belo
 w which pulsations cease. Furthermore we use the growth rate of the ion be
 am instability\, that generates the ULF waves upstream of the bow shock (w
 hich drive Pc3's)\, to explain the observed dependence of Pc3 pulsations o
 n solar wind density.\n\nhttps://events.saip.org.za/event/7/contributions/
 5190/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5190/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Validating The Auroral Zone Lower Ionosphere Model
DTSTART;VALUE=DATE-TIME:20110715T061500Z
DTEND;VALUE=DATE-TIME:20110715T063000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5198@events.saip.org.za
DESCRIPTION:Speakers: MICHAEL AFFUL (UNIVERSITY OF CAPE TOWN)\nThe ionosph
 ere is known to behave predictably as a function of solar zenith angle\, s
 olar activity and season. In the past\, analytical models have been develo
 ped to predict the behaviour of the ionosphere according to these paramete
 rs. This project aims to validate the IMAZ model\, a recently developed em
 pirical model for the lower ionosphere in the auroral zone to predict elec
 tron densities in the D-region as well as compare to other existing models
  designed for the same purpose. Rocket-bourne measurements were used as a 
 database of reliable lower ionosphere data. A response in the lower ionosp
 here was analysed based on the contribution of some input parameters. The 
 output was the electron density for a given set of inputs at a particular 
 pressure surface as predicted by the IMAZ model. Furthermore\, the ability
  of the IMAZ model to predict accurately within the auroral zone was estab
 lished and the need for further improvements was presented.\n\nhttps://eve
 nts.saip.org.za/event/7/contributions/5198/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5198/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Statistical Analysis of Outer Electron Radiation Belt Dropouts: Ge
 osynchronous and Low Earth Orbit Responses During Stream Interfaces
DTSTART;VALUE=DATE-TIME:20110715T101500Z
DTEND;VALUE=DATE-TIME:20110715T103000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5216@events.saip.org.za
DESCRIPTION:Speakers: Olakunle Ogunjobi (University of KwaZulu-Natal)\nThe
  OMNI-2 data set enables a correlation study of solar wind and geomagnetic
  parameters\, allowing the stream Interfaces events (SIs) to be examined. 
 A superposed epoch analysis of these events was performed to determine the
  threshold levels of IMF Bz and other geophysical parameters. Based on ene
 rgy\, temporal and spatial characteristics\, statistical analysis of elect
 ron flux data from LANL-SOPA and NOAA-POES satellites were use to study ou
 ter zone electron dropouts and precipitation. The deepest minimum of elect
 ron flux was observed after the impact of a SI\, which coincided with the 
 time of slower-decaying peak of electron precipitation. Result suggest tha
 t the mechanism causing the precipitation could also be responsible for th
 e observe electron flux dropout during Stream Interference.\n\nhttps://eve
 nts.saip.org.za/event/7/contributions/5216/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5216/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On TeV Gamma-rays from Galactic X-ray Binary Systems with H.E.S.S.
  array
DTSTART;VALUE=DATE-TIME:20110713T100000Z
DTEND;VALUE=DATE-TIME:20110713T101500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5205@events.saip.org.za
DESCRIPTION:Speakers: Isak Delberth Davids (North-West University\, Potche
 fstroom Campus)\nWith the birth of the new generation ground-based gamma-r
 ay imaging atmospheric Cherenkov telescope arrays (such as H.E.S.S.\, MAGI
 C and VERITAS)\, there is a growing need to probe X-ray binary stars for v
 ery high energy gamma-ray emissions. Since the discovery of the first extr
 a-solar X-ray binary (XRB)\, namely the Scorpius X-1 in 1962\, XRBs are no
 w well-established systems in the realm of X-ray astronomy. Today Scorpius
  X-1\, with X-ray output energy 100 000 times greater than the total radia
 tion of the Sun at all wavelengths\, is today known as a microquasar. In o
 rder to foster the multi-wavelength campaigns of the day\, we selected can
 didate XRBs from the Galaxy that were observed by H.E.S.S. for purposes of
  searching for significant TeV gamma-ray emission from these. Paredes (200
 8) confirmed four XRBs to be candidates that can be listed on the gamma-ra
 y sky map. These were PSR B1259-63\, LS I +61 303\, LS 5039 and Cygnus X-1
 . From a survey of 125 known XRBs\, Dickinson (2009) reported no conclusiv
 e detections of TeV emissions. The present study presents the Cherenkov te
 chnique\, a briefing on X-ray binaries\, known radiation mechanisms\, rele
 vant analysis techniques\, and report on the preliminary results of Galact
 ic XRBs that do not add any of the candidate XRBs to the envisaged catalog
 ue of TeV gamma-ray binaries. It is an astrophysical hope that the envisag
 ed CTA (Cherenkov Telescope Array)\, which may be hosted by South Africa\,
  will provide the anticipated discoveries\, providing a deep insight of th
 e TeV gamma-ray sky.\n\nhttps://events.saip.org.za/event/7/contributions/5
 205/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5205/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Constraining the Phase Space for Chameleon Dark Energy
DTSTART;VALUE=DATE-TIME:20110714T121500Z
DTEND;VALUE=DATE-TIME:20110714T123000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5210@events.saip.org.za
DESCRIPTION:Speakers: Muzikayise Sikhonde (University of Cape Town)\nA num
 ber of solutions to the dark energy problem have been proposed in literatu
 re\, the simplest is the cosmological constant Λ. But the cosmological co
 nstant lacks theoretical explanation for its extremely small value\, thus 
 dark energy is more generally modeled as quintessence scalar field rolling
  down a flat potential. For the quintessence scalar field to be evolving o
 n\ncosmological scales to day its mass must be of order H0 \, which is the
  present value of the Hubble constant. A scalar field φ whose mass varies
  with the background energy density was proposed by Khoury and Weltman(200
 3). This scalar field can evolve cosmologically while having coupling (β)
  to different matter fields of order unity. Such a scalar field also coupl
 es to photons in the presence of an external magnetic field via the φF2 i
 nteraction\, where F stands for the electromagnetic field strength tensor.
  The chameleon(φ)-photon coupling of this nature causes a conversion of p
 hotons to light Chameleon(φ) particles and vice versa. In this work we in
 vestigate this effect on pulsars\, and we constrain the parameter space of
  this theory.\n\nhttps://events.saip.org.za/event/7/contributions/5210/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5210/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Evaluation of satellites LAGEOS I and II\; general relativistic ac
 celerations in the Schwarzschild field of Earth
DTSTART;VALUE=DATE-TIME:20110715T094500Z
DTEND;VALUE=DATE-TIME:20110715T100000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5214@events.saip.org.za
DESCRIPTION:Speakers: Ludwig Combrinck (HartRAO)\nSolutions of General Rel
 ativity Theory (GRT) pertaining to space geodesy are weak field\, slow mot
 ion approximations.  These approximations are valid as the gravitational f
 ield in which the solutions are performed has a potential of small magnitu
 de and the velocities involved for any of the satellites are much smaller 
 than the velocity of light. The basic effects of GRT on space geodetic mea
 surements are related to how GRT affects the observables and dynamics of s
 atellite orbits. We evaluate the GRT accelerations ascribed to the Schwarz
 schild field\, as well as those due to Lense-Thirring precession (frame dr
 agging) and de Sitter precession. The Shapiro delay for a laser pulse as a
 pplied to Satellite LAser Ranging (SLR)is calculated and the importance of
  including this GRT correction in the range corrections for SLR is describ
 ed in terms of evaluation of the Observed-Computed residuals. Post-post Ne
 wtonian corrections are calculated and their relevance discussed in terms 
 of accuracy improvements.\n\nhttps://events.saip.org.za/event/7/contributi
 ons/5214/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5214/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Multi-instrument observations of spread F irregularities over Sout
 h Africa
DTSTART;VALUE=DATE-TIME:20110715T060000Z
DTEND;VALUE=DATE-TIME:20110715T061500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5217@events.saip.org.za
DESCRIPTION:Speakers: Emirant Bertillas Amabayo (SANSA Space Science and R
 hodes University)\nAn ionospheric eight year study (2001-2008) over South 
 Africa (SA) was conducted using ionosonde data observed by DPS-4 digisonde
 s with a time resolution of 10\, 15 and 30 minutes from Madimbo\, Grahamst
 own and Louisvale. Spread F (SF) characterized by ionograms is observed wh
 en the pulses returned from the F region of the ionosphere are of longer d
 uration than the transmitted signals. Separate occurrence of horizontal an
 d vertical spreading of the returned echoes from the ionosphere are classi
 fied as range spread F (RSF) and frequency spread F (FSF) respectively. Th
 e overlap of echoes of range and frequency spreading can occur simultaneou
 sly giving rise to mixed SF (MSF). These types of SF show a seasonal\, sol
 ar cycle and diurnal patterns over this midlatitude region. These variatio
 nal patterns were obtained by viewing the ionograms from the ionosondes ma
 nually using the SAO Explorer. The diurnal pattern of SF peaks between 23:
 00 UT and 00:00 UT for all seasons and types of SF in 2001 and 2005\, exce
 pt during autumn and spring (for RSF) in 2001. The \\% occurrence of both 
 MSF and FSF tends to increase with decreasing sunspot number (SSN). The MS
 F and FSF occurrence maximum are most frequent during the winter months in
  2007 and 2006 respectively.\n\nhttps://events.saip.org.za/event/7/contrib
 utions/5217/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5217/
END:VEVENT
BEGIN:VEVENT
SUMMARY:What Can We Learn from Phase Alignment of Gamma-ray and Radio Puls
 ar Light Curves?
DTSTART;VALUE=DATE-TIME:20110713T101500Z
DTEND;VALUE=DATE-TIME:20110713T103000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5221@events.saip.org.za
DESCRIPTION:Speakers: Christo Venter (North-west University\, Potchefstroo
 m Campus)\nThe Fermi Large Area Telescope (LAT) has revolutionized high-en
 ergy (HE) astronomy\, and is making enormous contributions particularly to
  gamma-ray pulsar science. As a result of the many new pulsar discoveries\
 , the gamma-ray pulsar population is now approaching 100. Some very famous
  millisecond pulsars (MSPs) have also been detected: J1939+2134 (a.k.a. B1
 937+21)\, the first MSP ever discovered\, as well as J1959+2048 (a.k.a. J1
 957+20)\, the first black widow pulsar system. These along with other MSPs
  such as PSR J0034-0534 and J2214+3000 (and also including the Crab pulsar
 )\, are unique among the pulsar population in that they exhibit nearly pha
 se-aligned radio and gamma-ray light curves (LCs). Traditionally\, pulsar 
 LCs have been modeled using standard HE models in conjunction with low-alt
 itude conal beam radio models. However\, a different approach is needed to
  account for phase-aligned LCs. We explored two scenarios: one where both 
 the radio and gamma-ray emission originate in the outer magnetosphere\, an
 d one where the emission comes from near the polar caps on the stellar sur
 face. We find best-fit LCs using a Markov Chain Monte Carlo technique for 
 the first class of models. The first scenario seems to be somewhat preferr
 ed\, as is also hinted at by the radio polarization data. This implies tha
 t the phase-aligned LCs are possibly of caustic origin produced in the out
 er magnetosphere\, in contrast to the usual lower-altitude conal beam radi
 o models. We lastly constrain the emission altitudes with typical uncertai
 nties of 10% of the light cylinder radius. The modelled pulsars are member
 s of a third gamma-ray MSP subclass\, in addition to two others with non-a
 ligned radio and gamma-ray LCs.\n\nhttps://events.saip.org.za/event/7/cont
 ributions/5221/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5221/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Frequency spectrum of nonlinear electric field structures in a mag
 netized dusty plasma
DTSTART;VALUE=DATE-TIME:20110715T070000Z
DTEND;VALUE=DATE-TIME:20110715T071500Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5230@events.saip.org.za
DESCRIPTION:Speakers: Shimul Kumar Maharaj (South African National Space A
 gency (SANSA) Space Science (formally NRF Hermanus Magnetic Observatory))\
 nA magnetized dusty plasma composed of an adiabatic negatively charged\ndu
 st fluid\, Boltzmann ions and Boltzmann electrons is considered for\nwhich
  coupled nonlinear dust-acoustic and dust-cyclotron waves hav-\ning sinuso
 idal\, sawtooth or spiky electric field waveforms are found\nto be support
 ed when charge neutrality is assumed (Maharaj et al\,\n2008). The focus of
  this investigation is to make use of a suitable Fast\nFourier Transform (
 FFT) algorithm to decompose the nonlinear waveforms into Fourier component
 s in an attempt to identify the dominant\nfrequency components of the nonl
 inear structures. The possibility of\nobtaining oscilloton solutions will 
 also be investigated.\n\nhttps://events.saip.org.za/event/7/contributions/
 5230/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5230/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Strong Gravitational Effects on Pulsar Signals Emanating from Clos
 e Compact Binary Systems
DTSTART;VALUE=DATE-TIME:20110714T071500Z
DTEND;VALUE=DATE-TIME:20110714T073000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5240@events.saip.org.za
DESCRIPTION:Speakers: Bevan Tucker (University of the Witwatersrand)\nThe 
 advent of the MeerKAT and SKA radio telescope projects will allow for vast
 ly improved precision in the measurement of pulsar radio frequency emissio
 ns.  Thus\, the propagation of a pulsar’s conical radio beam through the
  strong gravitational field region in the vicinity of a compact object\, i
 .e. black-hole or another neutron star\, will probe the metric of spacetim
 e in the high-field regime.  This talk outlines the theoretical and associ
 ated numerical predictions of General Relativistic effects\, such as the L
 ense-Thirring effect\, on such a pulsar signal.\n\nhttps://events.saip.org
 .za/event/7/contributions/5240/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5240/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ferromagnetic neutron stars
DTSTART;VALUE=DATE-TIME:20110714T064500Z
DTEND;VALUE=DATE-TIME:20110714T070000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5254@events.saip.org.za
DESCRIPTION:Speakers: Jacobus Diener (Stellenbosch University)\nIt is well
  known that neutron stars have very strong magnetic fields and that these 
 fields impact the behaviour of the star. The focus of our research is on t
 he interaction between the magnetic field and the constituent matter in th
 e neutron star’s interior. In particular we investigate the possibility 
 of a ferromagnetic phase in the neutron star interior being the source of 
 the star’s ultra-strong magnetic field.  Considering such a phase provid
 es us with a feedback mechanism between the constituent matter and the mag
 netic field and vice versa\, which we believe is a necessary component in 
 understanding the evolution of the neutron star’s magnetic field.  In th
 is talk we will shortly introduce a description of ferromagnetism in the n
 eutron star interior.  We will also discuss the impact of such a phase as 
 well as allude to possible observational consequences.\n\nhttps://events.s
 aip.org.za/event/7/contributions/5254/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5254/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Comparison of the THINGS HI and HERACLES CO Velocity Dispersion 
 in Nearby Galaxies
DTSTART;VALUE=DATE-TIME:20110714T101500Z
DTEND;VALUE=DATE-TIME:20110714T103000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5263@events.saip.org.za
DESCRIPTION:Speakers: Keoikantse Moses Mogotsi (UCT)\nIn this project data
  from The HI Nearby Galaxy Survey (THINGS) and from the HERA CO Extragalac
 tic Line Survey (HERACLES) is being used to compare the HI (neutral hydrog
 en) and CO dispersions in nearby galaxies in order to see if they are rela
 ted.  This is important in improving star formation laws (as they currentl
 y only use HI dispersions\, but stars form from molecular gas) and to bett
 er understand turbulence in galaxies. Preliminary analysis indicates that 
 the HI has higher velocity dispersions than the CO.\n\nhttps://events.saip
 .org.za/event/7/contributions/5263/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5263/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Orbital Environment Risk Assessment for SumbandilaSAT
DTSTART;VALUE=DATE-TIME:20110715T064500Z
DTEND;VALUE=DATE-TIME:20110715T070000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5270@events.saip.org.za
DESCRIPTION:Speakers: Chijioke Nwosa (NASSP/SAAO)\nSatellites have to oper
 ate in a hostile space environment that poses numerous threats from radiat
 ion\, charged particles\, residual atmosphere\, micrometeoritic impacts\, 
 space debris and other operational and defunct satellites.\nThe region of 
 outer space around the Earth is becoming polluted from anthropogenic space
  system junk and fragments. Currently\, according to US Space Surveillance
  Network\, 21\,000 objects (roughly 10cm or larger) orbiting Earth are tra
 cked.\nWith the Knowledge of the state of the Sun’s behavior\, in terms 
 of the 11-year solar cycle and sun-induced space weather phenomena\, the p
 assage through meteor showers and the population of known man-made space o
 bjects\, it is possible to model the environmental impositions on Sumbandi
 la during its operational lifetime.\nThis paper aims to assess the risk po
 sed by the natural space material and man-made space objects to Sumbandila
 SAT during its operational lifetime.\n\nhttps://events.saip.org.za/event/7
 /contributions/5270/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5270/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Optical study of the Southern high mass star forming region RCW 34
DTSTART;VALUE=DATE-TIME:20110714T094500Z
DTEND;VALUE=DATE-TIME:20110714T100000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5271@events.saip.org.za
DESCRIPTION:Speakers: Robert Czanik (North-West University\, Potchefstroom
 )\nTo understand the formation of stars one must be able to identify young
  objects. RCW 34 is a star forming region in the constellation of Vela. A 
 study was conducted in the near-infrared where it was found that a large n
 umber of stars surrounding the nebula shows NIR characteristics of lower m
 ass pre-main sequence stars. To prove the suspicions a follow-up study was
  conducted in the optical. The results of a photometric and spectroscopic 
 study on the the nebula and stars within a 7 arcmin x 7 arcmin region arou
 nd the nebula will be presented.\n\nhttps://events.saip.org.za/event/7/con
 tributions/5271/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5271/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NON-SPECIALIST: The Recommissioning of SALT
DTSTART;VALUE=DATE-TIME:20110713T090000Z
DTEND;VALUE=DATE-TIME:20110713T093000Z
DTSTAMP;VALUE=DATE-TIME:20260418T161205Z
UID:indico-contribution-284-5274@events.saip.org.za
DESCRIPTION:Speakers: Phil Charles (SAAO)\nFollowing the repair of the SAL
 T optics in late 2010\, the telescope has reentered the commissioning phas
 e with its principal scientific instruments\, SALTICAM and RSS.  Both thes
 e instruments have undergone major refurbishments in their own right\, and
  their current status and that of the telescope will be described\, togeth
 er with an update on its performance.\n\nhttps://events.saip.org.za/event/
 7/contributions/5274/
LOCATION: Acro2
URL:https://events.saip.org.za/event/7/contributions/5274/
END:VEVENT
END:VCALENDAR