"I don't know anything, but I do know that everything is interesting if you go into it deeply enough."
-Richard Feynman


Veronika Witzke

Currently, I am a postdoc at the Max-Planck Institute for Solar System Research, working in the SolVe group, where I investigate how fundamental stellar parameters affect the radiation transfer in the photosphere and how this in turn can change stellar brightness variations on the magnetic activity time-scale.

Before, that I did my PhD research in the Department of Mathematics at City, University of London under the supervision of Lara Silvers, where I worked on fluid dynamics and Magnetohydrodynamics applied in astrophysical objects. In particular I investigate instabilities and turbulence occurring in stellar interiors by solving the fully compressible Navier-Stokes equations numerically.

Previous to that, I finished a Master of Science in Physics at the Ludwig-Maximilian University of Munich in 2013.

Research Interests

  • Stellar brightness variability
  • Radiative transfer in stellar atmospheres
  • Fluiddynamics, especially magnetohydrodynamics, instabilities and turbulence
  • Non-linear 3D simulations by using direct numerical calculations

    • Publications

    First author:

    Witzke, V., Reinhold, T., Shapiro, A.I., Krivova, N. A., Solanki, S. K. (in preparation) The effect of metallicity on the detectability of rotational periods in Sun-like stars

    Witzke, V., Silvers, L. J. and Favier, B. (2019). Evolution and characteristics of forced shear flows in polytropic atmospheres: large and small Peclet number regimes, MNRAS, 482, Issue 1. doi: 10.1093/mnras/sty2698

    Witzke V., Shapiro, A. I., Solanki, S. K., Krivova, N. A., and Schmutz, W. (2018) From Solar to Stellar Brightness Variations: The Effect of Metallicity and Effective Temperature , Astronomy and Astrophysics, 619, A146. doi: 10.1051/0004-6361/201833936

    Witzke, V., Silvers, L. J. and Favier, B. (2016). Evolution of forced shear flows in polytropic atmospheres: A comparison of forcing methods and energetics , MNRAS, 463, 282. doi: 10.1093/mnras/stw1925

    Witzke, V., Silvers, L. J. and Favier, B. (2015). Shear instabilities in a fully compressible polytropic atmosphere , Astronomy and Astrophysics, 577, A76. doi: 10.1051/0004-6361/201425285

    Co-author:

    Cernetic, M., Shapiro, A. I., Witzke, V., Krivova, N. A., Solanki, S. K., Tagirov, R. V. (2019) Opacity distribution functions for stellar spectra synthesis (accepted in Astronomy and Astrophysics)

    Dudok de Wit, T., Kopp, G., Shapiro, A. I., Witzke, V., Kretzschmar, M. (2018) Response of Solar Irradiance to Sunspot-area Variations The Astrophysical Journal, 853:197 (10pp)

    Christoffer Karoff, Travis S. Metcalfe, Ângela R. G. Santos, Benjamin T. Montet, Howard Isaacson, Veronika Witzke, Alexander I. Shapiro, Savita Mathur, Guy R. Davies, Mikkel N. Lund, Rafael A. Garcia, Allan S. Brun, David Salabert, Pedro P. Avelino, Jennifer van Saders, Ricky Egeland, Margarida S. Cunha, Tiago L. Campante, William J. Chaplin, Natalie Krivova, Sami K. Solanki, Maximilian Stritzinger, and Mads F. Knudsen. (2018) The Influence of Metallicity on Stellar Differential Rotation and Magnetic Activity The Astrophysical Journal, 852:46 (12pp)

    Selected Presentations

    Talks:

    'Does the Sun behave unusually for a Sun-like star?' February 2018
    Co-authors: A. I. Shapiro, S. K. Solanki, N. A. Krivova
    Conference: IAU Symposium 340 - Jaipur, India

    'Effect of Metallicity on Stellar Brightness Variability' Sept 2017
    Co-authors: A. I. Shapiro, S. K. Solanki, N. A. Krivova
    Conference: AG Meeting, Göttingen, Germany

    Invited Seminar: ‘How Investigating Shear-Driven Turbulence Helps to Understand Stellar Interiors’, Dec 2016
    Co-authors: Silvers, L. J. Favier, B.
    Solar Group Seminar: MPS, Göttingen, Germany

    ‘Dynamo Action in Turbulent Fully Compressible Shear Flows’, May 2016
    Co-authors: Silvers, L. J. Favier, B.
    Conference: UK MHDMeeting, Glasgow, UK

    ‘Shear Instabilities in a Fully Compressible Polytropic Atmosphere’ April 2015
    Co-authors: Silvers, L. J. Favier, B.
    Conference: Joint British Mathematical Colloquium & British Applied Mathematics Colloquium, Cambridge


    Posters:


    ‘Turbulent regime of a Kelvin-Helmholtz instability in a compressible fluid’ June 2015
    Co-authors: Silvers, L. J. Favier, B.
    Summer school: International HPC Summer School, Toronto


    ‘Shear Instabilities in a fully compressible polytropic atmosphere’ August 2014
    Co-authors: Silvers, L. J. Favier, B.
    Conference: A meeting in honour of Chris Jones’ 65th year, Newcastle

    Press-release paper

    Max-Planck Scientists explain why the Sun's brightness vary. (Picture is © NASA/SDO)