Latest News Archive

Please select Category, Year, and then Month to display items
Previous Archive
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

Hearing loss a silent public health crisis in South Africa
2017-03-27

Description: Hearing loss a silent public health crisis in South Africa Tags: Hearing, Deaf, World Hearing Day
Dr Magteld Smith engages on the topic of hearing loss
and how it coincides with the commemoration of
World Hearing awareness during the month of March.
Photo: Oteng Mpete 

Communication is a principal challenge for people with hearing loss. It can be difficult to negotiate everyday interactions, whether in the workplace, on the street, in classrooms, courts, during consultations with health professionals, or even when contacting the police. The World Health Organisation’s (WHO) World Hearing Day is an annual advocacy event held each year on 3 March to raise awareness and promote ear and hearing care across the world. In many countries this awareness campaign usually starts on 3 March but many continue to create awareness for the full month of March. 

Hearing loss is a global reality
According to Dr Magteld Smith, a researcher at the University of the Free State (UFS) School of Medicine’s Department of Otorhinolaryngology, unaddressed hearing loss poses a high cost for the economy globally and has a significant impact on the lives of those affected. Interventions to address hearing loss are available in South Africa but are not accessible or affordable for most citizens. This is partly because not only persons with hearing loss but also people with disabilities experience barriers in accessing services that many of us take for granted, including health, education, employment, and transport as well as information. These difficulties are exacerbated in less-advantaged communities.

“WHO estimates that there are more than 360 million persons with hearing loss globally. The statistics in South Africa are unreliable due to the different definitions used by Statistics South Africa and the absence of training of the officials who conduct and collect statistics concerning hearing loss in South Africa,” says Dr Smith. 

According to Dr Smith, analysis from retrospective studies reflects that about 17 out of 1 000 infants are born daily in South Africa with severe to profound hearing loss. However, Dr Smith states that the number could be higher because of late diagnosis, high levels of undiagnosed and untreated hearing loss. This excludes young adults, adults and the elderly as well as children with acquired (become deaf after birth) hearing loss.

Crisis that needs urgent intervention 
Dr Smith says hearing loss is an emergency which the South African government fails to prioritise. She says that research published confirms that the risk compounding the projected increase in hearing loss that comes with an ageing population. This is a looming and silent public-health crisis.
She believes that the government should take urgent action to align research-spending with the current and projected size and impact of hearing loss. It should also collaborate across related conditions, such as vision, neurodegenerative diseases and neurological conditions. Furthermore, the government needs, and is obligated, to deliver more accessible and integrated services and develop quality standards that take account of the whole pathway – linking public health, clinical and social needs.

We use cookies to make interactions with our websites and services easy and meaningful. To better understand how they are used, read more about the UFS cookie policy. By continuing to use this site you are giving us your consent to do this.

Accept