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28 October 2019 | Story Leonie Bolleurs | Photo Anja Aucamp
Dr Brain van Soelen and Prof Pieter Meintjies
UFS scientists, Prof Pieter Meintjes and Dr Brian van Soelen, are part of the prestigious H.E.S.S. collaboration that recently published in Nature Astronomy.

Think of an object with a mass exceeding that of the Sun, squeezed into a volume of a sphere with the radius of a city like Bloemfontein. This very dense, compact object, known as a pulsar, is also a great source of energy. According to Physics Professor, Prof Pieter Meintjes, this pulsar (neutron star produced in supernova explosion) is also a key element of a recently submitted paper in Nature Astronomy.

Prof Meintjes and Dr Brian van Soelen, Senior Lecturer, both from the Department of Physics at the University of the Free State (UFS), were part of the High Energy Stereoscopic System (H.E.S.S.) collaboration of 220-plus scientists worldwide who worked on the paper Resolving the Crab pulsar wind nebula at tera-electronvolt energies, published in the prestige journal Nature Astronomy. 

According to Prof Meintjes, the fact that the paper was accepted for publication in Nature Astronomy testifies of the importance of this finding in the high-energy astrophysics community.

Powerful generators of electricity

He elaborates on the study: “The name pulsar originates from the fact that rotating neutron stars produced in supernova explosions produce beams of radiation, much like a lighthouse. Every time the beam intersects the observer’s line of sight, the observer receives a pulse of radiation.”

“As a result of this enormous mass squeezed into a small volume, these objects have the same density as that of an atomic nucleus. These objects (very dense pulsars) spin very rapidly and have enormous magnetic fields; for example, the pulsar at the centre of the Crab Nebulae spins around its axis once every 33 milliseconds (millisecond: one thousandth of a second) and possesses a magnetic field strength of the order of one tera-Gauss (tera – million x million). For comparison, the average strength of the Earth’s magnetic field is 0.5. Gauss and the magnetic field strength on the Sun ranges between 1 000 and 4 000 Gauss.”

“Because of this very super-strong rapid-spinning magnet, enormous electric fields are induced that can accelerate particles such as electrons and protons to energies in excess of one tera-electronvolt (optical light that are emitted by an ordinary lightbulb has energies of the order of one electronvolt).”

Prof Meintjes continues: “This means that these fast-rotating neutron stars are extraordinary powerful generators of electricity, which fills the surrounding cloud (supernova remnant) with super-high energy-charged particles that can produce, in turn, very high energy gamma rays through various processes such as synchrotron radiation and inverse-Compton radiation, to name a few.”

H.E.S.S. collaboration 

Above one tera-electronvolt, the gamma rays are detected by huge ground-based telescopes such as H.E.S.S., utilising the Earth’s atmosphere.

“When these high-energy gamma rays enter the atmosphere, they produce showers of super-relativistic particles that produce Cherenkov light – detected by the telescope. The technique is called the Atmospheric Cherenkov Technique (ACT).”

HESS
The High Energy Stereoscopic System. (Photo: Supplied)

“The H.E.S.S. gamma-ray collaboration is but one collaboration that has studied this source intensively over the past couple of decades or so.  Being the most powerful gamma-ray telescope facility currently operational, very careful analysis of the data managed to reveal that the gamma-ray emitting region inside the nebula is about 10 times bigger in size than the region where the x-rays are emitted within the nebula.” 

“This has solved a long-standing question as to how big the gamma-ray emitting region within these supernova remnants are, compared to the region where the x-rays, for example, originates,” says Prof Meintjes. 

Both Prof Meintjes and Dr Van Soelen are members of this prestigious H.E.S.S. collaboration. Their participation in this project, together with scientists from universities such as the University of Oxford, the University of Leicester, and the University of Bordeaux, opens up valuable research opportunities for UFS postgraduate students to enter the international stage and interact with the best scientists in the world.

They are also members of the editorial board responsible for the internal review of research papers before being submitted to more prestigious journals, for example, Nature Astronomy. Dr Van Soelen is also a coordinator of multi-wavelength follow-up observations within the H.E.S.S. collaboration. 

This is the second time that Prof Meintjes published in Nature Astronomy. Previously, he was co-author of a paper on emission from a white dwarf pulsar, showing that fast-rotating white dwarf stars could in fact mimic emission from neutron star pulsars. He developed the theoretical model reported in that paper, explaining the multi-wavelength emission from radio to X-ray energies.


News Archive

Ford foundation funds higher education redesign
2005-06-23

 

The Ford Foundation has pledged a grant of almost R280 000 for redesigning higher education delivery at three campuses in the Free State.

According to Prof Magda Fourie, Vice-Rector: Academic Planning at the University of the Free State (UFS), the three campuses that will be affected by the strategic reconfiguration of higher education delivery are the Qwaqwa campus at Phuthaditjhaba and the Vista campus of the UFS in Bloemfontein and the Welkom campus of the Central University of Technology (CUT).

Prof Fourie says the three campuses were all affected by the restructuring of higher education, in line with the National Plan for Higher Education.

The Qwaqwa campus of the UFS that was part of the former University of the North was incorporated into the UFS in January 2003.  Likewise the Bloemfontein campus of the former Vista University was incorporated into the UFS in January 2004.

The Welkom campus of the CUT was also part of the former Vista University and was incorporated into the CUT in January 2004.

“These incorporations pose a challenge in that we have to think creatively about the best ways of using these three campuses to service the higher education, training, skills development and human resource needs of the Free State,” Prof Fourie said.

“The grant from the Ford Foundation will primarily be used to draw up strategic funding proposals for the three campuses.  The Qwaqwa campus of the UFS is a priority to us given the poverty and unemployment in a largely rural area of the Free State,” said Prof Fourie.

“A detailed consultation process will be undertaken in the Qwaqwa campus sub-region which will hopefully result in a comprehensive and a coherent suite of higher education activities being established on this campus,” said Prof Fourie.

“It is envisaged that the Qwaqwa campus will become a centre of excellence in the area of rural development.  This vision is based on a focused integration of the core functions of a university – teaching, research, and community service – around the issue of rural development,” said Prof Fourie.

Prof Fourie said that various educational offerings including among others short courses, bridging and foundation programmes, and degrees could be offered, with a particular focus on providing courses of relevance to students from the local rural community and students from elsewhere with an interest in focusing on rural development studies.

She said the redesign of the three affected campuses is being managed as a project of the Free State Higher Education Consortium (FSHEC) consisting of all the higher education institutions operating in the Free State.

“The aim of the project is to establish how the Qwaqwa and Vista campuses of the UFS and the Welkom campus of the CUT can be used effectively to meet regional education and training needs, to serve the strategic priorities of the two higher education institutions and contribute to the sustainable development and poverty alleviation of the region,” she said.

The planning for the Vista campus of the UFS is still in an early stage.  “We are looking at the possibility of developing this campus into a hub of education and training opportunities for Bloemfontein and Free State region.  Further plans will be communicated later in the year,” said Prof Fourie.

Media release

Issued by:  Lacea Loader
   Media Representative
   Tel:  (051) 401-2584
   Cell:  083 645 2454
   E-mail:  loaderl.stg@mail.uovs.ac.za

23 June 2005
 

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