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Article in prestigious Nature Astronomy sheds light on energy generation

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

SRC Inauguration speech: 22 January 2005

2005-01-22

Campus Head (Prof Peter Mbati). Dean of Students (Dr Natie Luyt). Deputy Director: Student Affairs and my boss (Mr. Teboho Manchu), Members of the University executive and Academic staff members, SRC members, Leaders of trade Unions and Student organizations, Distinguished guests, Ladies and gentlemen, most importantly first entering students and Parents receive my heartfelt revolutionary greetings.

Let me extend my word of appreciation to our distinguished guests for adding value and dignity to this event. Your presence here means a lot to us. Program Director what I bring here with me, assisted by facts, and is therefore just the work of my imagination. Like a love letter addressed to a sweetheart miles away, even though you do not know how she feels, what she wants to hear, and do not even know how her face looks like.

To me a speech is just an honest and intimate conversation. That is why I got into the habit of establishing a dialogue, or a debate, with my acquaintances looking at their faces and trying to persuade them of what I am telling them.

Mr. Speaker and Madam Deputy Speaker of the Student Parliament we are gathering at this ceremony, significantly few weeks after the release of grade 12 results, with the exception of those from Mpumalanga because of fraud. The Grade 12 results also show that only 18% of Black learners matriculated with exemptions, as compared to 53, 6% of white learners. This is an indication that our education system needs an overhaul.

We are also gathered here significantly a day after the management retreat held in Bloemfontein, Masselspoort. The retreat discussed, among other things, the transformation agenda, and some possible solutions to challenges we are facing now.

Most regrettably, we are gathered here when the whole world morns the victims of Tsunami tragedy. Let me therefore tore the line and convey our deepest condolences, from the last robot of my heart, to the affected families. Our hearts and thoughts will always be occupied by this horrified tragedy.

Creating a new Institution

I would submit, for purposes of debate and discussions that this Institution should strive to specialize and excel in regional rural development studies. Since our higher education, institutions in South Africa are generally weak in rural development studies. Instead, most of them tend to have an urban orientation to their programmes. Training everybody for the cities, big business and the private sector. This is a big weakness in a country with such large rural areas and population trapped in poverty, disease and ignorance.

Women’s studies

Program Director, it is only a moron who can argue against the fact that for us to reposition the institution around the regional development challenge, we need to start first with women empowerment. It is a fact that in most of our poor communities and families, it is women who withstand the worst of poverty. They are the ones who daily have to wipe tears from children who are hungry. It is women who look after the sick, the elderly, those dying from AIDS and the jobless. They are the one who have to fetch water, make fire and cook. There can therefore be no rural development studies without women studies, in particular on how to empower them and assist in the provision of basic services, so that they are relieved from some of the burdensome task of the society.

Registration Process

Mr. Speaker and Madam Deputy Speaker of the Student Parliament let me indicate that the registration is a process and not an event, so it cannot be concluded overnight. This huge process demands for people to stay calm, as there is no crisis. People should stop being excited. At the same time, no organization should use its cheap popularity and unilaterally disrupt the continuous and smooth running of the registration process at hand.

Let me strongly indicate, madam deputy speaker, that I am on record for stating that I have forgiven all those who have wronged us. I harbour no bitterness towards the protagonists of our painful and unfortunate events of the past week. And we will overcome this process not by our own devices but by the help of Almighty God and the grace of our Lord Jesus Christ.

Concerning registration of first years, we have programs, concerning that of senior students, we have programs, regarding graduations we have programs, and concerning HIV\AIDS we have programs. So, there is no need for people to press panicking buttons.

Mr. Speaker and Madam Deputy Speaker of the Student Parliament let me be opportunistic and welcome the entire student body on Campus for the academic year 2005. May our lovely first entering students have a happy and momentous year as part of Qwaqwa Campus of University of the Free State. May your studies be fruitful and enjoyable.

Student years are generally the happiest years of your life, so please make the most of them. While you are doing, all your preparations bear in mind that University is not an opportunity, it is just creating opportunities for a person.

On behalf of SRC members, our people, our students and management members I would like to welcome you all. Even though your parents are far away, here at Uniqwa you have more brothers, more sisters and more parents. Since we will love you with the same love as if we are from one family, and I have no doubts that management members will love and care for you as if you are their own children. Should you encounter any problem while studying at the Qwaqwa Campus of University of the Free State do not hesitate to contact us at the SRC offices because we need to ameliorate any factor influencing you negatively while on campus. I wish you well in the attainment of your academic pursuit.

Senior Students: We are not faced with just a new year but another academic year where we all have to work together to achieve our common goal of building our Institution through the development of human power. I urge you to invest your whole selves in this SRC.

For quite some time now, a debate has been ranging as to, whether has there been any progress in this incorporation process, or we are just moving with no direction. This debate is important, but I hasten to add not essential. The SRC is also involved in this debate, but with definite shift in emphasis. For us it is not important to participate in the debate than it is in finding solutions for the challenges of this new chapter in the history of humankind.

To my colleagues: Comrades, we are leading this Institution with a sense of pride and duty, and I know very well that we lead men and women, students who are determined to ensure that we all reach our destination safely and on time.

I said in one of our meetings that there are more enemies on our way, more than we can imagine. I think you witnessed that during the course of this week. The excitement and unnecessary confusions caused by some confused and loosed charlatans bear testimony to my statements. We should not reveal our game plans unless we are ready to slam.

Let me also borrow from the words of the late Albert Lethuli when he said and I quote: “There remains before us the building of the new land, from the ruins of the old narrow groups, a synthesis of the rich cultural strains which we have inherited. The task is immense”. Lastly, a navy divided within its ranks will be vanquished and destroyed by the enemy, but a navy united in purpose and action, loyalty and commitment will not drawn but sail on to victory.

In conclusion, let me call upon all political structures, church denominations, developmental structures, clubs, societies and forums to put aside all their differences, ideological insinuations and forge unity towards transforming Qwaqwa Campus of University of the Free State into an institution that is seen playing vigilant role in developing students academically, politically, socially, spiritually, religiously, culturally and otherwise.

Program Director, let me end my speech by indicating that every drop of my blood is telling me that Uniqwa is my home. I firstly became a student here, I became an activist here, I became a leader here, I became a president here, I will become a graduant here and hopefully I will become an employee here. So never, doubt my commitment towards the community of this campus.

Please be informed, in a central University of Technology’s way, that if there is no UNIQWA in HEAVEN, then I am not GOING.

Let us broaden the social base.

Tello Titus Wa-Motloung President General

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