J
Jörn Warnecke
Researcher at Max Planck Society
Publications - 87
Citations - 1878
Jörn Warnecke is an academic researcher from Max Planck Society. The author has contributed to research in topics: Dynamo & Magnetic field. The author has an hindex of 24, co-authored 82 publications receiving 1470 citations. Previous affiliations of Jörn Warnecke include Nordic Institute for Theoretical Physics & Aalto University.
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Journal ArticleDOI
Chromospheric activity catalogue of 4454 cool stars - Questioning the active branch of stellar activity cycles
S. Boro Saikia,S. Boro Saikia,Christopher Marvin,Sandra V. Jeffers,Ansgar Reiners,Robert H. Cameron,Stephen C. Marsden,Pascal Petit,Pascal Petit,Jörn Warnecke,Abhay Pratap Yadav +10 more
TL;DR: In this paper, a chromospheric activity index, S-index, was measured for 304 main-sequence stars from archived high-resolution HARPS spectra, and the measured and archived S-indices were converted into the chromosphere flux ratio log R0 HK.
Journal ArticleDOI
Effects of enhanced stratification on equatorward dynamo wave propagation
Petri J. Käpylä,Petri J. Käpylä,Maarit J. Mantere,Maarit J. Mantere,Elizabeth Cole,Jörn Warnecke,Jörn Warnecke,Axel Brandenburg,Axel Brandenburg +8 more
TL;DR: In this paper, the authors present results from simulations of rotating magnetized turbulent convection in spherical wedge geometry representing parts of the latitudinal and longitudinal extents of a star, and test the domain size dependence of their results for a rapidly rotating run with equatorward migration by varying the longitudinal extent of our wedge.
Journal ArticleDOI
The Pencil Code, a modular MPI code for partial differential equations and particles: multipurpose and multiuser-maintained
Axel Brandenburg,Anders Johansen,Philippe-A. Bourdin,Wolfgang Dobler,Wladimir Lyra,Matthias Rheinhardt,Sven Bingert,Nils Erland L. Haugen,Antony J. Mee,Frederick A. Gent,Natalia Babkovskaia,Chao-Chin Yang,T. Heinemann,Boris Dintrans,Dhrubaditya Mitra,Simon Candelaresi,Jörn Warnecke,Petri J. Käpylä,Andreas Schreiber,Piyali Chatterjee,Maarit J. Käpylä,Xiang-Yu Li,Jonas Krüger,Jørgen R. Aarnes,Graeme R. Sarson,Jeffrey S. Oishi,Jennifer Schober,Raphaël Plasson,Christer Sandin,Ewa Karchniwy,Luiz Felippe S. Rodrigues,Alexander Hubbard,Gustavo Guerrero,A. P. Snodin,I. R. Losada,Johannes Pekkilä,Chengeng Qian +36 more
TL;DR: The Pencil Code is a highly modular physics-oriented simulation code that can be adapted to a wide range of applications, primarily designed to solve partial differential equations of compressible hydrodynamics but can also evolve Lagrangian particles, their coagulation and condensation, as well as their interaction with the fluid.
Journal ArticleDOI
Multiple dynamo modes as a mechanism for long-term solar activity variations
Maarit J. Käpylä,Petri J. Käpylä,Petri J. Käpylä,Petri J. Käpylä,N. Olspert,Axel Brandenburg,Jörn Warnecke,Jörn Warnecke,Bidya Binay Karak,Bidya Binay Karak,Jaan Pelt,Jaan Pelt +11 more
TL;DR: In this paper, the authors analyze a solution of a solar-like DNS that was evolved for roughly 80 magnetic cycles of 4.9 years and where epochs of irregular behavior are detected.
Journal ArticleDOI
On The Cause of Solar-like Equatorward Migration in Global Convective Dynamo Simulations
Jörn Warnecke,Petri J. Käpylä,Petri J. Käpylä,Maarit J. Käpylä,Axel Brandenburg,Axel Brandenburg +5 more
TL;DR: In this paper, the authors present results from four convectively driven stellar dynamo simulations in spherical wedge geometry, and show that the migration direction can be explained by an αΩ dynamo wave following the Parker-Yoshimura rule.