Musical sounds created by longitudinal vibrations within the Sun's atmosphere, have been recorded and accurately studied for the first time by experts at the University of Sheffield, shedding light on the Sun's magnetic atmosphere.
Using state-of-the-art mathematical theory combined with satellite observations, a team of solar physicists from the University have captured the music on tape and revealed the harmonious sounds are caused by the movement of giant magnetic loops in the solar corona - the outermost, mysterious, and least understood layer of the Sun's atmosphere. Most importantly, the team studied how this sound is decaying, giving an unprecedented insight into the physics of the solar corona.
High-resolution images taken by a number of satellites show that the solar corona is filled with large banana-shaped magnetic structures known as coronal loops. It is thought that these giant magnetic loops, some of them over a few 100,000 km long, play a fundamental role in governing the physics of the corona and are responsible for huge atmospheric explosions that occur in the atmosphere, known as solar flares.
These giant coronal loops have also been observed to undergo periodic (oscillatory) motion, which can be thought of as someone plucking a guitar string (transversal oscillations) or blowing the wind-pipe instrument (longitudinal oscillations). With the length and thickness of the string fixed, the pitch of the note is determined by the tension of the string and the tone is made up of the harmonics of the modes of oscillation.
In this sense, the solar atmosphere is constantly pervaded by the music of the coronal loops. The coronal music also provides scientists with a unique and unprecedented tool to study the magnetic solar atmosphere, as the motion of these loops is determined by their local surroundings. This technique is known as solar magneto-seismology and is very similar to the seismology methods used by geologists studying earthquakes.
Studying this magnetic solar atmosphere will help the team, which is headed-up by Professor Robertus von Fáy-Siebenbürgen and includes postgraduate student Richard Morton and postdoctoral research associate Dr Youra Taroyan, all from the Dept of Applied Mathematics, make further breakthroughs into understanding one of the key and central unresolved problems of modern astrophysics, i.e. the heating of solar and tellar coronal plasmas, and reveal the underlying physical processes: Are there millions of localised magnetic explosions releasing the energy necessary to maintain the corona at millions of degrees or is the physics related to the numerous waves propagating from the internal regions of the Sun toward its outer regions, reaching even space around the Earth's atmosphere.
The discovery was presented by the University experts to an audience of MPs both from the House of Commons and the House of Lords at the House of Commons Marquee, as well as and senior scientists representing prestigious institutions such as the Royal Society, after being selected by the Parliamentary and Scientific Committee.
The next step for the team will be to develop cutting edge numerical modelling that will be able to give further insight into the sub-resolution properties of coronal loops, i.e. on spatial scales that are not even observable with the latest high-resolution satellites available to scientist.
This is the second solar related breakthrough made by experts at the University. The way in which the solar corona is heated to temperatures of over a million degrees had, until recently, remained a long-standing puzzle of solar and space physics, as this region of the sun is even further away from the centre of energy production than the underlying solar surface. However Professor von Fáy-Siebenbürgen and his team last month solved this enigma and revealed that Transition Region Quakes - described by the experts as 'mega-tsunamis' - power the lower base of the solar corona.
The news comes as the University of Sheffield launches a unique venture entitled Project Sunshine, led by the Faculty of Science. The Project aims to unite scientists across the traditional boundaries in both the pure and applied sciences to harness the power of the sun and tackle the biggest challenge facing the world today: meeting the increasing food and energy needs of the world´s population in the context of an uncertain climate and global environment change. It is hoped that Project Sunshine will change the way scientists think and work and become the inspiration for a new generation of scientists focused on solving the world´s problems.
Professor Robertus von Fáy-Siebenbürgen from the University of Sheffield's Department of Applied Mathematics and Head of SP2RC, said: "The results of our latest coronal research, presented in the Parliament at Westminster, allow us to gain a fundamentally new insight into the fascinating but at the same time very mysterious solar atmosphere. I'm most proud to have such talented young scientists within my research group and department. The invitation by SET for Britain and our collaborative research efforts clearly demonstrate our international leadership position in the field of solar physics."
Mega-tsunami hits House of Commons: Sheffield Solar Physicists at Parliament
A bid prepared by Sheffield solar physicists of SWAT/SP2RC (Solar WAve Theory Group, Solar Physics and Space Plasma Research Centre, Dept of Applied Mathematics) on the discovery of solar Transition Region Quakes have been selected, by SET for Britain on behalf of the Parliamentary and Scientific Committee, for presentation (8 March 2010) at the House of Commons Marquee to members of both Houses of Parliament at Westminster. The team involves our postgraduate student Mr Eamon Scullion, a postdoctoral research associate Dr Viktor Fedun and their supervisor Professor Robert von Fay-Siebenburgen all from the Dept of Applied Mathematics. Mr Scullion is a joint location PhD student and carries out his research both in Sheffield and Armagh Observatory (co-supervised by Professor Gerry Doyle).
The Transition Region is located about 2000km above the Sun´s visible surface, and is the narrow layer of sharp transition in density and temperature between the relatively cool solar chromosphere (10-20,000 K) and the 1-10 MK very hot upper corona. A long-standing puzzle of solar and space physics is how the solar corona is heated to temperatures of over a million degrees, especially as this region of the Sun is even further away from the centre of energy production than the underlying solar surface . This enigma may be addressed by first understanding what powers the lower base of the solar corona. TRQs that are a sort of mega-tsunami generated by narrow (a few 100 km radius), long (10-40,000 km) rapidly rising (10-100 km/s) plasma jets. When these jets hit the Transition region, they excite a wealth of TRQs that is now observed and modelled the first time. It is our estimate that at any moment of time there are about 60,000 of these mega-tsunamis splashing and crashing around the Transition Region. Their energy may provide a key to understand the long-standing secret of solar coronal heating.
For more information contact Prof Robert von Fay-Siebenburgen, Head of SP2RC (0114-2223832) or via email robertus [at] shef.ac.uk. (15-02-2010) New!
Pioneering Insights into Giant Solar Twists
The puzzling and dramatic increase in the solar temperature from the visible surface of the Sun (photosphere) to well over a million degrees of the overlaying tenuous ubiquitously magnetised solar corona, has remained at the forefront of astrophysical research for over half a century. An international collaboration of solar physicists between the University of Sheffield, Queen's University Belfast and California State University (Northridge), have found unambiguous evidence for a new breed of wave phenomena under solar circumstances.
An expanding solar magnetic structure sandwiched between the solar surface (photosphere) and its middle atmosphere (chromosphere).
Observations, based on some theoretical predictions and calculations led by Professor Robertus Erdelyi (Head of the Solar Physics and Space Plasma Research Centre, SP2RC, Dept of Applied Mathematics, Univeristy of Sheffield) were designed by scientists from Queen's University, Dr David Jess and Professor Mihalis Mathioudakis, and have been carried out by using the Swedish Solar Telescope in the Canary Islands, to detect for the first time purely magnetic waves in the Sun's lower atmosphere. The specific quest was to search for large-scale torsional magnetic oscillations in the turbulent and dynamic solar atmosphere. These unique magnetic oscillations, also called Alfven waves, are fundamental for the energy household of the solar atmosphere. Alfven waves may also crucially determine Space Weather, and offer the much-sought-after solution to the almost century-long problem of solar and stellar atmospheric heating.
The detailed findings of this important discovery is published in the illustrious Science magazine on Friday, March 20th 2009. For a full account click here, or contact Prof. Robertus Erdelyi via email robertus [at] shef.ac.uk. (20-03-2009)
BIOMASS mission selected by ESA for next stage of development
A space mission to measure the amount of carbon stored as woody material in the Earth's forests, proposed by Prof. Shaun Quegan and colleagues, has just been selected by the European Space Agency (ESA) to go to the next stage of development for launch in 2016. The key sensor on the BIOMASS mission is a long-wavelength radar which can measure both forest biomass and forest height. These measurements will go a long way towards reducing the present huge uncertainties in our knowledge of how tropical deforestation affects the carbon cycle, as well as giving unprecedented global maps showing how biomass is distributed in the world´s forests. The next two years will be devoted to reducing the technical and scientific risks of the mission. This will open up a range of exciting research opportunities as we move progressively towards making the mission a reality.
Prof. Shaun Quegan was the co-lead proposer on the mission, coordinated the Report for Assessment, and presented the mission at the crucial selection meeting in Lisbon on 20-21 Jan 2009. See the website of CTCD for more information. (19-Feb-2009)
