We’re delighted that the European Physics Society Solar Physics Division (EPS-SPD) chose to award its 2018 ESPD PhD Prize to Dr. Peter Levens “for significant contributions to the study of tornado-like prominences – using detailed ultraviolet spectroscopic, multi-wavelength imaging and visible spectropolarimetric observational analysis – helping to unveil the nature of these structures.”
Peter’s PhD work was under the supervision of Nic Labrosse and Lyndsay Fletcher. Peter also spent four months at the Observatoire de Paris in Meudon, working with Dr. Brigitte Schmieder.
European Week of Astronomy and Space Science press release
RAS PR 18/20 (EWASS 16)
Despite their appearance solar tornadoes are not rotating after all, according to a European team of scientists. A new analysis of these gigantic structures, each one several times the size of the Earth, indicates that they may have been misnamed because scientists have so far only been able to observe them using 2-dimensional images. Dr Nicolas Labrosse will present the work, carried out by researchers at the University of Glasgow, Paris Observatory, University of Toulouse, and Czech Academy of Sciences, at the European Week of Astronomy and Space Science (EWASS) in Liverpool on Friday 6 April.
Solar tornadoes were first observed in the early 20th century, and the term was re-popularised a few years ago when scientists looked at movies obtained by the AIA instrument on the NASA Solar Dynamics Observatory (SDO). These show hot plasma in extreme ultraviolet light apparently rotating to form a giant structure taking the shape of a tornado (as we know them on Earth).
Now, using the Doppler effect to add a third dimension to their data, the scientists have been able to measure the speed of the moving plasma, as well as its direction, temperature and density. Using several years’ worth of observations, they were able to build up a more complete picture of the magnetic field structure that supports the plasma, in structures known as prominences.
Dr Nicolas Labrosse, lead scientist in the study, explains: “We found that despite how prominences and tornadoes appear in images, the magnetic field is not vertical, and the plasma mostly moves horizontally along magnetic field lines. However we see tornado-like shapes in the images because of projection effects, where the line of sight information is compressed onto the plane of the sky.”
Dr Arturo López Ariste, another member of the team, adds: “The overall effect is similar to the trail of an aeroplane in our skies: the aeroplane travels horizontally at a fixed height, but we see that the trail starts above our heads and ends up on the horizon. This doesn’t mean that it has crashed!”
Giant solar tornadoes – formally called tornado prominences – have been observed on the Sun for around a hundred years. They are so called because of their striking shape and apparent resemblance to tornadoes on Earth, but that is where the comparison ends.
Whereas terrestrial tornadoes are formed from intense winds and are very mobile, solar tornadoes are instead magnetized gas. They seem to be rooted somewhere further down the solar surface, and so stay fixed in place.
“They are associated with the legs of solar prominences – these are beautiful concentrations of cool plasma in the very hot solar corona that can easily be seen as pink structures during total solar eclipses,” adds Labrosse.
“Perhaps for once the reality is less complicated than what we see!” comments Dr Brigitte Schmieder, another scientist involved in the work.
She continues: “Solar tornadoes sound scary but in fact they normally have no noticeable consequences for us. However, when a tornado prominence erupts, it can cause what’s known as space weather, potentially damaging power, satellite and communication networks on Earth.”
Media contacts
Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877 699
ewass-press@ras.ac.uk
Ms Anita Heward
Royal Astronomical Society
Mob: +44 (0)7756 034 243
ewass-press@ras.ac.uk
Dr Morgan Hollis
Royal Astronomical Society
Mob: +44 (0)7802 877 700
ewass-press@ras.ac.uk
Dr Helen Klus
Royal Astronomical Society
ewass-press@ras.ac.uk
Ms Marieke Baan
European Astronomical Society
ewass-press@ras.ac.uk
Science contacts
Dr Nicolas Labrosse
School of Physics and Astronomy
University of Glasgow
Mob: +44 (0)7983 380 380
Nicolas.Labrosse@glasgow.ac.uk
Dr Brigitte Schmieder
Observatoire de Paris
Université Paris-Diderot
Tel : +33 (0)1 4507 7817
Brigitte.Schmieder@obspm.fr
Dr Arturo López Ariste
Institut de Recherche en Astrophysique et Planétologie
Université de Toulouse
Tel : +33 (0)5 6133 4716
Arturo.LopezAriste@irap.omp.eu
Animation and caption
A solar tornado observed by the NASA satellite SDO between 23 April and 29 April 2015. The tornado prominence erupted on 28 April. An image of the Earth is superimposed for scale.
Credit: SDO data courtesy of NASA. Movie created using the ESA and NASA funded Helioviewer Project.
Images and captions
https://www.ras.org.uk/images/stories/EWASS2018/Labrosse/composite_plot.png
Composite image of the prominence observed on 15 July 2014 showing, after co-alignment: the EIS raster in green, the IRIS slit-jaw image in red, and an SOT image in blue. The white contours show the THEMIS D3 intensity image and indicate where the tornadoes are observed in extreme ultraviolet. The background image is an AIA 304 angstrom image (greyscale).
Credit: P. Levens
https://www.ras.org.uk/images/stories/EWASS2018/Labrosse/prominence.jpg
Composite image of an erupting solar prominence observed by SDO on 31 August 2012.
Credit: NASA / SDO / GSFC
Dr Nicolas Labrosse will be giving an outreach talk on this topic at the Merseyside Astronomy Day (MAD) on Saturday 7 April. Full details can be found at: http://www.astro.ljmu.ac.uk/mad/labrosse.html
The full team consists of:
Dr Nicolas Labrosse, SUPA, School of Physics and Astronomy, University of Glasgow, UK
Dr Peter Levens, SUPA, School of Physics and Astronomy, University of Glasgow, UK
Dr Arturo López Ariste, Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, CNES, France
Dr Brigitte Schmieder, LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris-Diderot, Sorbonne Paris Cité, Meudon, France
Dr Maciej Zapiór, Astronomical Institute, Academy of Sciences of the Czech Republic, Ondřejov, Czech Republic
Details of the techniques used to obtain these results can be found in the following publications:
B. Schmieder, M. Zapior, A. Lopez Ariste, P. Levens, N. Labrosse, R. Gravet, “Reconstruction of a helical prominence in 3D from IRIS spectra and images”; A&A, 606, A30 (2017)
B. Schmieder, P. Mein, N. Mein, P. Levens, A. Lopez Ariste, N. Labrosse, L. Ofman, “H alpha Doppler shifts in a tornado in the solar corona”; A&A, 597, 109 (2017)
P. Levens, B. Schmieder, N. Labrosse, A. Lopez Ariste, “Structure of prominence legs: plasma and magnetic fields”; ApJ, 818, 31 (2016)
P. Levens, B. Schmieder, A. Lopez Ariste, N. Labrosse, K. Dalmasse, B. Gelly, “Magnetic field in atypical prominences: Bubble, tornado and eruption”; ApJ, 826, 164 (2016)
P. Levens, N. Labrosse, B. Schmieder, A. Lopez Ariste, L. Fletcher, “Comparison between UV/EUV line parameters and magnetic field parameters in a quiescent prominence with tornadoes”; A&A, 607, A16 (2017)
Notes for editors
The European Week of Astronomy and Space Science (EWASS 2018) will take place at the Arena and Conference Centre (ACC) in Liverpool from 3 – 6 April 2018. Bringing together around 1500 astronomers and space scientists, the conference is the largest professional astronomy and space science event in the UK for a decade and will see leading researchers from around the world presenting their latest work.
EWASS 2018 is a joint meeting of the European Astronomical Society and the Royal Astronomical Society. It incorporates the RAS National Astronomy Meeting (NAM), and includes the annual meeting of the UK Solar Physics (UKSP) group. The conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and Liverpool John Moores University (LJMU).
Liverpool John Moores University (LJMU) is one of the largest, most dynamic and forward-thinking universities in the UK, with a vibrant community of 25,000 students from over 100 countries world-wide, 2,500 staff and 250 degree courses. LJMU celebrated its 25th anniversary of becoming a university in 2017 and has launched a new five-year vision built around four key ‘pillars’ to deliver excellence in education; impactful research and scholarship; enhanced civic and global engagement; and an outstanding student experience.
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We’re delighted that the EPS Solar Physics Division chose to award its first-ever 2017 ESPD Early Career Prize to Dr. Natasha Jeffrey “for significant contributions to the physics of solar flares and for inspiring outreach activities”.
The 2017 ESPD Prizes will be presented in the course of the 15th European Solar Physics Meeting, during an award ceremony specifically designed for this event.
Peter Levens, a PhD student in the Astronomy and Astrophysics Group, has won the School of Physics and Astronomy’s Thomson Prize for his second year report on Solar Tornadoes in Prominences.
Well done Peter!
Differential Emission Measure (left) and Emission Measure Distribution (right) for a location in the solar tornado. From Levens et al (2015) A solar tornado observed by EIS: plasma diagnostics. Astronomy and Astrophysics, 582, A27. (doi:10.1051/0004-6361/201425586)
Two solar scientists from the Glasgow group are currently observing the Sun with the THEMIS telescope at the Observatorio del Teide on the Island of Tenerife.
These observations will be part of a larger observing campaign in coordination with other instruments, including more ground-based observatories (Solar Tower of Observatoire de Meudon, Fuxian Solar Observatory) and satellites (SDO, Hinode, IRIS).
The objective is the measurement of magnetic fields in prominences and tornadoes, exploiting the excellent spectro-polarimetric capabilities of THEMIS in the He D3 line to infer the magnetic field vector. These phenomena represent unique examples of the small-scale coupling between magnetic field and plasma in environments with distinct dynamical behaviour. As such they represent key case studies for deepening our understanding of the Sun.
Peter Levens is pointing the telescope on an attractive target.
The A&A group receives a major boost with funding from the European Commission’s Seventh Framework Programme (FP7) for space-related research.
A powerful X-class flare observed by Hinode’s Solar Optical Telescope (SOT) on Dec. 13, 2006
Dr. Lyndsay Fletcher and Dr Nicolas Labrosse from the Astronomy & Astrophysics group in the School of Physics and Astronomy will investigate the physics of solar flares.
The F-CHROMA project (Flare CHRomospheres: Observations, Models and Archives) will bring together experts from seven institutions to collect, synthesise and analyse data from satellite and earthbound observations of solar flares. Solar flares are energetic outbursts of solar radiation which span the whole electromagnetic spectrum. Mid-sized flares can release energy equivalent to a hundred million megatons of TNT in just a few minutes, most of which ultimately turns into electromagnetic radiation. This radiation is emitted primarily by a thin, and complicated, part of the Sun’s atmosphere called the chromosphere.
Lyndsay Fletcher, Principal Investigator, said that this project will allow the team to combine ultra-high detail observation of solar flare events with advanced theoretical and computational modeling to shed light on the way a flare’s energy is stored, released, and converted into other forms.
The outcomes of F-CHROMA will be used to inform preparations for major forthcoming projects including the Daniel K. Inouye Solar Telescope which will see first light in 2019 in Hawai’i and ESA’s Solar Orbiter Mission which is expected to start beaming back solar images and spectra from its orbit in the inner solar system at around the same time.
F-CHROMA is one of two projects led by the University of Glasgow receiving funding from the European Commission.
SDO/AIA images of a filament on the sun from August 31, 2012. From upper left and going clockwise: 335, 171, 304 and 131 Å channels
Registration is now open for the Royal Astronomy Society Specialist Discussion Meeting devoted to solar prominences on Friday 21st February in the RAS premises in London, UK. Abstracts can be submitted at the meeting web page.
This specialist discussion meeting aims to review our current understanding of the life-cycle of solar prominences. How do they form? How do they interact with their environment, from the photosphere to the corona? How do they disappear? What is their contribution to Space Weather? Addressing these questions relies on interactions between experts in plasma physics, MHD, magnetic field modelling and observation, spectroscopy, radiation transfer, … This will be an excellent opportunity to discuss open issues in this area of interest to solar and stellar physicists, keeping in mind recent and future developments in observations and in modelling.
An exciting opportunity for an outstanding intern to work on a project entitled “Computer Vision for Space Applications” has arisen in the College of Science and Engineering at the University of Glasgow.
Images in science carry a lot of information. As image resolution increases, extracting information in a timely manner and providing it to end-users is more and more challenging. It requires analysing and interpreting automatically a large amount of data from different instruments, as well as rapid and robust image processing algorithms such as feature extraction, image mosaic and time series analysis.
Depending on the preferences of the successful candidate, the intern will focus on one or more of the following areas:
− Feature extraction: the intern will develop computer vision tools to automatically extract and classify features of interest from satellite images.
− Time-tracking: the intern will implement time-tracking algorithms to perform crucial time series analyses to reveal trends and processes from the data.
− Benchmarking: the intern will design test cases allowing reliable comparisons between different algorithms developed by the project leaders to assess and enhance their performance and robustness.
The project will last for ten weeks with a start date preferably between 15th and 30th June 2012. IDL programming skill is highly desirable. To apply, please email the following documents to both Dr Labrosse and Dr Li: (1) a one-page CV including academic grades, (2) a brief statement of why you are interested in this project and how you fit the proposed projects, and (3) one letter of reference. Deadline is 31 May 2012.
Contact Dr Nicolas Labrosse (School of Physics and Astronomy) and Dr Zhenhong Li (School of Geographical and Earth Sciences) for further information.
Evolution of the 2010-06-13 prominence eruption. The circle marks the part of the prominence which was tracked. The field of view in the images is 300 × 300 arcsec.
Theoretical calculations have shown that when solar prominences move away from the surface of the Sun, their radiative output is affected via the Doppler dimming or brightening effects. In this paper co-authored between Dr Nicolas Labrosse and undergraduate student Kris McGlinchey we ask whether observational signatures of the changes in the radiative output of eruptive prominences can be found in EUV (extreme ultraviolet) observations of the first resonance line of ionised helium at 304 Å. We also investigate whether these observations can be used to perform a diagnostic of the plasma of the eruptive prominence. We find that observations of intensities in various parts of the four eruptive prominences studied here are sometimes consistent with the Doppler dimming effect on the He II 304 Å line. However, in some cases, one observes an increase in intensity in the 304 channel with velocity, in contradiction to what is expected from the Doppler dimming effect alone. The use of the non-LTE models allows us to explain the different behaviour of the intensity by changes in the plasma parameters inside the prominence, in particular the column mass of the plasma and its temperature.
