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Sven Wedemeyer

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Visiting address Sem Sælands vei 13 Svein Rosselands hus 0371 OSLO
Postal address Postboks 1029 Blindern 0315 OSLO

A rare sight on our Sun: A heart-shaped sunspot. (Credits: Wedemeyer, Jafarzadeh & Franz 2015).

Happy Valentine's Day greetings from your Sun!

On May 7th, 2015, a team of solar physicists caught this beautiful sight when directing the 1.5-m GREGOR telescope at the Sun: A heart-shaped sunspot. Sven Wedemeyer and Shahin Jafarzadeh from the University of Oslo, together with their colleague Morten Franz from the Kiepenheuer Institute for Solar Physics in Germany, were among the first to use the new 1.5-m GREGOR telescope at the Observatorio del Teide on Tenerife, Canary Islands, Spain, as part of a SolarNet-funded observing campaign.

The sunspot, apart from its peculiar heart-warming shape, is rather small but still shows the typical features of a sunspot like the dark umbra and the penumbra around it. The latter consists of thin threads pointing away from the umbra, following magnetic field lines. The magnetic field in the dark heart-shaped umbra of the sunspot is very strong and hampers the transport of energy from the layers below towards the surface. As a result, the gas in the sunspot is slightly cooler than in the surrounding and thus appears darker, although still being as hot as roughly 3000 to 4000 degrees Celsius. In the outer areas of the image, the bright surface of the Sun with it's characteristic granulation pattern is present, which is produced by hot gas bubbles rising to the surface.


The sunspot was part of the active region AR 12338, located not too far from the center of the solar disk. The image was taken in the G-band around a wavelength of 430 nm and depicts the visible surface layer of the Sun, i.e. the photosphere.

Acknowledgments: The observing campaign was supported by SOLARNET for the project "Vortex flows in the solar atmosphere". The SOLARNET Trans-national Access and Service Programme is supported by the European Commission (FP7, Grant Agreement 312495). The GREGOR telescope is operated by the Kiepenheuer-Institut für Sonnenphysik, Freiburg i.Br., Germany.


About Sven Wedemeyer

Since 2006, I work at the Institute of Theoretical Astrophysics at the University of Oslo, first as a Marie Curie Intra-European Fellow and now as a Researcher. Before coming to Oslo, I have been working at the Kiepenheuer Institute in Freiburg i.Br., Germany, and at the University of Kiel, Germany, where I did most of my studies, and at the University of Glasgow, UK. I am currently leading the VORTEX project funded by the Research Council of Norway, which aims at a detailed understanding of vortex flows in the atmosphere of our Sun and their role for the transport of energy and mass. Since 2014, I am coordinating the international research network SSALMON with now more than 70 researchers. In 2015, I was awarded a Consolidator Grant by the European Research Commission (ERC) for the project "ALMA - The key to the Sun’s coronal heating problem." The SolarALMA project is foreseen to run from 2016 to 2021 with a team of 4 (post-doctoral) researchers and 2 PhD students.

My primary research fields are solar and stellar physics with additional interests in extra-solar planets. Most of my individual projects can be summarized as realistic numerical simulations in comparison with space-borne and ground-based observations.

Recent research highlights include the discovery and explanation of so-called magnetic tornadoes on the Sun, featured on the front page of Nature in 2012, and the ongoing development of methods for observing the Sun with the Atacama Large Millimeter/submillimeter Array, an application with potentially high impact for our understanding of the outer layers of our Sun and other stars.

Please refer to my detailed personal homepage (http://folk.uio.no/svenwe/) for more general information and to http://www.solartornado.info/  for more information on my 2012 Nature article ("Magnetic tornadoes as energy channels into the solar corona") and related work.


Current major research fields:

  • "ALMA - Solar Observations with the Atacama Large Millimeter Array
    • The ERC-funded SolarALMA project runs from 2016 to 2021 and aims at utilizing ALMA for detailed studies of the solar chromosphere with particular focus on the coronal heating problem.
    • External staff member of the ALMA Regional Center at Ondrejoy, Czech Republic
    • Co-I of the project "Advanced Solar Observing Techniques" within the North American Study Plan for Development Upgrades of the ALMA (PI: T. Bastian, NRAO, USA)
    • Team member of the project "Solar Research with ALMA" carried out at the Czech node of the European ALMA Regional Center (EU ARC at Ondrejov, Czech Republic) in the frame of the ESO program "Enhancement of ALMA Capabilities/EoC" (PI: R. Brajsa, Hvar Observatory, Croatia).
    • Coordinator of SSALMON - The Solar Simulations for the Atacama Large Millimeter Observatory Network, which was officially launched on September 1st, 2014.


  • "Vortex flows and magnetic tornadoes on the Sun and cool stars"
    Funded by the Research Council of Norway in the highly competetive FRIPRO/FRINATEK program for the period 2013-2017.
    Click here for the official ITA project page.

  • "Magnetic Activity of the Atmospheres of M-type Dwarf Stars "
    Funded by the Research Council of Norway in the Space Science for the period 2012-2014. Further work based on the project results still ongoing.
    Click here for the official ITA project page.

  • "Magnetic Activity of M-type Dwarf Stars and the Influence on Habitable Extra-solar Planets"

Tags: Astronomy and Astrophysics, Solar Physics, Observations, Simulations, Computational Astrophysics, Solar Chromosphere, Stars, Extrasolar Planets, Atacama Large Millimeter/submillimeter Array (ALMA), Nordic Optical Telescope

Publications

  • Phillips, Neil; Hills, Richard; Bastian, Timothy; Hudson, Hugh; Marson, Ralph & Wedemeyer, Sven (2015). Fast single-dish scans of the Sun using ALMA . Astronomical Society of the Pacific Conference Series.  ISSN 1050-3390.  499, s 347- 348
  • Tremblay, P. E.; Fontaine, G.; Freytag, B.; Steiner, O.; Ludwig, Hans-Günter; Steffen, M.; Wedemeyer, Sven & Brassard, P. (2015). ON the EVOLUTION of MAGNETIC WHITE DWARFS. The Astrophysical Journal.  ISSN 0004-637X.  812(1) . doi: 10.1088/0004-637X/812/1/19
  • Wedemeyer, Sven; Bastian, T.; Brajsa, R.; Hudson, H.; Fleishman, G.; Loukitcheva, M.; Fleck, B.; Kontar, Eduard P.; De Pontieu, Bart Walter; Yagoubov, P.; Tiwari, S. K.; Soler, R.; Black, J. H.; Antolin, Patrick; Scullion, Eamon; Gunar, S.; Labrosse, N.; Ludwig, H.-G.; Benz, A. O.; White, S. M.; Hauschildt, P.; Doyle, J. G.; Nakariakov, V. M.; Ayres, T.; Heinzel, P.; Karlicky, M.; Van Doorsselaere, Tom; Gary, D.; Alissandrakis, C. E.; Nindos, A.; Solanki, S. K.; Rouppe, Van Der Voort Luc; Shimojo, M.; Kato, Yoshiaki; Zaqarashvili, T.; Perez, E.; Selhorst, C. L. & Barta, M. (2015). Solar Science with the Atacama Large Millimeter/Submillimeter Array—A New View of Our Sun. Space Science Reviews.  ISSN 0038-6308.  s 1- 73 . doi: 10.1007/s11214-015-0229-9
  • Wedemeyer, Sven; Bastian, Timothy; Brajša, Roman; Barta, Miroslav; Hudson, Hugh; Fleishman, Gregory; Loukitcheva, Maria; Fleck, Bernhard; Kontar, Eduard P.; De Pontieu, Bart Walter; Tiwari, Sanjew; Kato, Yoshiaki; Soler, Roberto; Yagoubov, Pavel; Black, John; Antolin, Patrick; Gunar, Stanislav; Labrosse, Nicolas; Benz, Arnold; Nindos, Alexander; Steffen, Matthias; Scullion, Eamon Michael; Doyle, Gerry; Zaqarashvili, Teimuraz; Hanslmeier, Arnold; Nakariakov, Valery; Heinzel, Petr; Ayres, Thomas & Karlicky, Marian (2015). SSALMON - The Solar Simulations for the Atacama Large Millimeter Observatory Network. Advances in Space Research.  ISSN 0273-1177.  56(12), s 2679- 2692 . doi: 10.1016/j.asr.2015.05.027
  • Wedemeyer, Sven; Bastian, Timothy; Brajša, Roman; Barta, Miroslav & Shimojo, Masumi (2015). Solar Simulations for the Atacama Large Millimeter Observatory Network . Astronomical Society of the Pacific Conference Series.  ISSN 1050-3390.  499, s 341- 342
  • Wedemeyer, Sven; Bastian, Timothy; Brajša, Roman; Barta, Miroslav; Shimojo, Masumi; Hales, Antonio; Yagoubov, Pavel & Hudson, Hugh (2015). Solar ALMA Observations - A new view of our host star . Astronomical Society of the Pacific Conference Series.  ISSN 1050-3390.  499, s 345- 346
  • Wedemeyer, Sven & Parmer, Asbjørn Lie (2015). ALMA's high-cadence imaging capabilities for solar observations . Astronomical Society of the Pacific Conference Series.  ISSN 1050-3390.  499, s 343- 344
  • Freij, N.; Scullion, Eamon; Nelson, C. J.; Mumford, S.; Wedemeyer-Böhm, Sven & Erdélyi, R. (2014). The detection of upwardly propagating waves channeling energy from the chromosphere to the low corona. The Astrophysical Journal.  ISSN 0004-637X.  791(1) . doi: 10.1088/0004-637X/791/1/61
  • Scullion, Eamon; Rouppe, Van Der Voort Luc; Wedemeyer-Böhm, Sven & Antolin, Patrick (2014). Unresolved Fine-Scale Structure in Solar Coronal Loop-Tops. The Astrophysical Journal.  ISSN 0004-637X.  797(1) . doi: 10.1088/0004-637X/797/1/36
  • Wedemeyer-Böhm, Sven & Steiner, Oskar (2014). On the plasma flow inside magnetic tornadoes on the Sun. Nippon Tenmon Gakkai obun kenkyu hokoku.  ISSN 0004-6264.  66(1) . doi: 10.1093/pasj/psu086
  • Ayres, T. R.; Lyons, J. R.; Ludwig, Hans-Günter; Caffau, E. & Wedemeyer-Böhm, Sven (2013). IS THE SUN LIGHTER THAN THE EARTH? ISOTOPIC CO IN THE PHOTOSPHERE, VIEWED THROUGH THE LENS OF THREE-DIMENSIONAL SPECTRUM SYNTHESIS. The Astrophysical Journal.  ISSN 0004-637X.  765(1) . doi: 10.1088/0004-637X/765/1/46
  • Ayres, T. R.; Lyons, J. R.; Ludwig, Hans-Günter; Caffau, E. & Wedemeyer-Böhm, Sven (2013). Solar carbon monoxide: poster child for 3D effects. Memorie della Societa Astronomica Italiana Supplement.  ISSN 1824-0178.  24, s 85- 95
  • Wedemeyer-Böhm, Sven (2013). The CO5BOLD analysis tool. Memorie della Societa Astronomica Italiana Supplement.  ISSN 1824-0178.  24, s 96- 99
  • Wedemeyer-Böhm, Sven; Ludwig, Hans-Günter & Steiner, Oskar (2013). Three-dimensional magnetohydrodynamic simulations of M-dwarf chromospheres. Astronomical Notes - Astronomische Nachrichten.  ISSN 0004-6337.  334(1-2), s 137- 140 . doi: 10.1002/asna.201211741
  • Wedemeyer-Böhm, Sven; Scullion, Eamon; Rouppe, Van Der Voort Luc; Bosnjak, Antonija & Antolin, Patrick (2013). Are Giant Tornadoes the Legs of Solar Prominences?. The Astrophysical Journal.  ISSN 0004-637X.  774(2) . doi: 10.1088/0004-637X/774/2/123
  • Wedemeyer-Böhm, Sven; Scullion, Eamon; Steiner, Oskar; de la Cruz Rodriguez, Jaime & Rouppe, Van Der Voort Luc (2013). Magnetic tornadoes and chromospheric swirls - Definition and classification. Journal of Physics, Conference Series.  ISSN 1742-6588.  440(1) . doi: 10.1088/1742-6596/440/1/012005
  • Freytag, Bernd; Steffen, Matthias; Ludwig, Hans-Günter; Wedemeyer-Böhm, Sven; Schaffenberger, Werner & Steiner, Oskar (2012). Simulations of stellar convection with CO5BOLD. Journal of Computational Physics.  ISSN 0021-9991.  231(3), s 919- 959 . doi: 10.1016/j.jcp.2011.09.026
  • Wedemeyer-Böhm, Sven; Scullion, Eamon; Steiner, O.; Rouppe, Van Der Voort Luc; de la Cruz Rodriguez, Jaime; Fedun, V. & Erdélyi, R. (2012). Magnetic tornadoes as energy channels into the solar corona. Nature.  ISSN 0028-0836.  486(7404), s 505- 508 . doi: 10.1038/nature11202
  • Wedemeyer-Böhm, Sven & Carlsson, Mats (2011). Non-equilibrium calcium ionisation in the solar atmosphere. Astronomy and Astrophysics.  ISSN 0004-6361.  528 . doi: 10.1051/0004-6361/201016186
  • Haberreiter, Margit; Finsterle, W; McIntosh, S.W. & Wedemeyer-Böhm, Sven (2010). Toward the analysis of waves in the solar atmosphere based on NLTE spectral synthesis from 3D MHD simulations. MEMORIE della Società Astronomica Italiana.  ISSN 0037-8720.  81, s 782- 785
  • Kjeldseth-Moe, Olav & Wedemeyer-Böhm, Sven (2010). Are there variations in Earth's global mean temperature related to the solar activity?. Proceedings of the International Astronomical Union.  ISSN 1743-9213.  5, s 320- 325 . doi: 10.1017/S1743921309992869
  • Wedemeyer-Böhm, Sven (2010). Small-scale structure and dynamics of the chromospheric magnetic field. MEMORIE della Società Astronomica Italiana.  ISSN 0037-8720.  81, s 693- 700
  • Wöger, Friedrich; Wedemeyer-Böhm, Sven; Uitenbroek, H. & Rimmele, T. R. (2010). Recovering the line-of-sight magnetic field in the chromosphere from Ca II IR spectra. MEMORIE della Società Astronomica Italiana.  ISSN 0037-8720.  81, s 598- 603
  • Wedemeyer-Böhm, Sven; Lagg, Andreas & Nordlund, Åke (2009). Coupling from the Photosphere to the Chromosphere and the Corona. Space Science Reviews.  ISSN 0038-6308.  144(1-4), s 317- 350 . doi: 10.1007/s11214-008-9447-8
  • Wedemeyer-Böhm, Sven & Rouppe, Van Der Voort Luc (2009). On the continuum intensity distribution of the solar photosphere. Astronomy and Astrophysics.  ISSN 0004-6361.  503(1), s 225- 239 . doi: 10.1051/0004-6361/200911983
  • Wedemeyer-Böhm, Sven & Rouppe, Van Der Voort Luc (2009). Small-scale swirl events in the quiet Sun chromosphere. Astronomy and Astrophysics.  ISSN 0004-6361.  507(1), s L9- L12 . doi: 10.1051/0004-6361/200913380
  • Wedemeyer-Böhm, Sven & Rouppe, Van Der Voort Luc (2009). The solar continuum intensity distribution. Settling the conflict between observations and simulations. MEMORIE della Società Astronomica Italiana.  ISSN 0037-8720.  80
  • Wöger, Friedrich; Wedemeyer-Böhm, Sven; Uitenbroek, H. & Rimmele, T. R. (2009). MORPHOLOGY AND DYNAMICS OF THE LOW SOLAR CHROMOSPHERE. The Astrophysical Journal.  ISSN 0004-637X.  706(1), s 148- 157 . doi: 10.1088/0004-637X/706/1/148
  • Wedemeyer-Böhm, Sven & Wöger, Friedrich (2008). Small-scale structure and dynamics of the lower solar atmosphere, In R. Erdélyi & C. A. Mendoza-Briceno (ed.),  Waves and Oscillations in the Solar Atmosphere: Heating and Magneto-Seismology.  Cambridge University Press.  ISBN 0-521-874696.  Chapter.  s 66 - 73
  • Steiner, Oskar; Rezaei, Rezza; Schaffenberger, Werner & Wedemeyer-Böhm, Sven (2008). The Horizontal Internetwork Magnetic Field: Numerical Simulations in Comparison to Observations with Hinode. The Astrophysical Journal.  ISSN 0004-637X.  680(1), s L85- L88
  • Wedemeyer-Böhm, Sven (2008). Point spread functions for the Solar optical telescope onboard Hinode. Astronomy and Astrophysics.  ISSN 0004-6361.  487, s 399- 412 . doi: 10.1051/0004-6361:200809819
  • Wedemeyer-Böhm, Sven; Lagg, Andreas & Nordlund, Åke (2008). Coupling from the photosphere to the chromosphere and the corona. Space Science Reviews.  ISSN 0038-6308.  OnlineFirst . doi: 10.1007/s11214-008-9447-8
  • Leenaarts, Jorrit; Wedemeyer-Böhm, Sven; Carlsson, Mats Per-Olof & Hansteen, Viggo (2007). Non-equilibrium Hydrogen Ionization in the Solar Atmosphere, In Petr Heinzel; Ivan Dorotovic & Robert Rutten (ed.),  The Physics of Chromospheric Plasmas.  Astronomical Society of the Pacific.  ISBN 978-1-583812-36-5.  368.  s 103 - 106
  • Rezaei, R.; Steiner, O.; Wedemeyer-Böhm, Sven; Schlichenmaier, R.; Schmidt, W. & Lites, B.W. (2007). Hinode observations reveal boundary layers of magnetic elements in the solar photosphere. Astronomy and Astrophysics.  ISSN 0004-6361.  476, s L33- L36 . doi: 10.1051/0004-6361:20078371
  • Steiner, O.; Vigeesh, G.; Krieger, L.; Wedemeyer-Böhm, Sven; Schaffenberger, W. & Freytag, B. (2007). First local helioseismic experiments with CO(5)BOLD. Astronomical Notes - Astronomische Nachrichten.  ISSN 0004-6337.  328 . doi: 10.1002/asna.200610738
  • Wedemeyer-Böhm, Sven; Ludwig, HG; Steffen, M.; Leenaarts, J. & Freytag, B. (2007). Inter-network regions of the Sun at millimetre wavelengths. Astronomy and Astrophysics.  ISSN 0004-6361.  471, s 977- 991 . doi: 10.1051/0004-6361:20077588
  • Wedemeyer-Böhm, Sven & Steffen, M. (2007). Carbon monoxide in the solar atmosphere II. Radiative cooling by CO lines. Astronomy and Astrophysics.  ISSN 0004-6361.  462, s L31- L35 . doi: 10.1051/0004-6361:20066173
  • Wedemeyer-Böhm, Sven; Steiner, O.; Bruls, J. & Rammacher, W. (2007). What is Heating the Quiet-Sun Chromosphere?, In Petr Heinzel; Ivan Dorotovic & Robert Rutten (ed.),  The Physics of Chromospheric Plasmas.  Astronomical Society of the Pacific.  ISBN 978-1-583812-36-5.  368.  s 93 - 102
  • Leenaarts, Jorrit & Wedemeyer-Boehm, S. (2006). Time-dependent hydrogen ionisation in 3D simulations of the solar chromosphere - Methods and first results. Astronomy and Astrophysics.  ISSN 0004-6361.  460, s 301- 307

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  • Wedemeyer, Sven (2015). Rød sol og evig daggry: Leting etter liv på fjerne kloder, I: Jostein Riiser Kristiansen; Anna Kathinka Dalland Evans; Henrik Svensen; Bjørn Hallvard Samset & Hanne Sigrun Byhring (red.),  Stjerneklart – siste nytt fra verdensrommet.  Spartacus.  ISBN 9788243009738.  Kapittel 15.  s 96 - 108
  • Ayres, T. R.; Lyons, J. R.; Ludwig, Hans-Günter; Caffau, E. & Wedemeyer-Böhm, Sven (2013). Isotopic CO in the Solar Photosphere, Viewed Through the Lens of 3D Spectrum Synthesis.
  • Wedemeyer-Böhm, Sven & van der Voort, Luc Rouppe (2010). The solar continuum intensity distribution. Proceedings of the International Astronomical Union.  ISSN 1743-9213.  15, s 333- 334
  • Kjeldseth-Moe, Olav & Wedemeyer-Böhm, Sven (2009). Are there variations in Earth’s global mean temperature related to the solar activity?.
  • Rezaei, Rezza; Steiner, Oskar; Wedemeyer-Böhm, Sven; Schlichenmaier, Rolf & Lites, Bruce W. (2007). Variation of the Stokes-V area asymmetry across magnetic elements. Astronomical Notes - Astronomische Nachrichten.  ISSN 0004-6337.  328(7), s 706
  • Wedemeyer-Böhm, Sven (2007). Small-scale structure and dynamics of the lower solar atmosphere.

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Published Nov 3, 2010 03:21 PM - Last modified Feb 14, 2016 12:07 AM