Publications (136)
Electronic and magnetic nano phase separation in cobaltates LaSrCoO
Z. W. Li, Y. Drees, A. Ricci +11
The single-layer perovskite cobaltates have attracted enormous attention due to the recent observation of hour-glass shaped magnetic excitation spectra which resemble the ones of t…
Numerical dissipation and the bottleneck effect in simulations of compressible isotropic turbulence
W. Schmidt, W. Hillebrandt, J. C. Niemeyer
The piece-wise parabolic method (PPM) is applied to simulations of forced isotropic turbulence with Mach numbers . The equation of state is dominated by the Fermi pr…
Detection of large acoustic energy flux in the solar atmosphere
N. Bello González, M. Franz, V. MartÃnez Pillet +9
We study the energy flux carried by acoustic waves excited by convective motions at sub-photospheric levels. The analysis of high-resolution spectropolarimetric data taken with IMa…
A nonlinear structural subgrid-scale closure for compressible MHD Part II: a priori comparison on turbulence simulation data
P. Grete, D. G. Vlaykov, W. Schmidt +1
Even though compressible plasma turbulence is encountered in many astrophysical phenomena, its effect is often not well understood. Furthermore, direct numerical simulations are ty…
Thermonuclear explosions of rapidly rotating white dwarfs - I. Deflagrations
J. M. M. Pfannes, J. C. Niemeyer, W. Schmidt +1
Context: Turbulent deflagrations of Chandrasekhar mass White Dwarfs are commonly used to model Type Ia Supernova explosions. In this context, rapid rotation of the progenitor star…
The Numerical Simulation of Turbulence
W. Schmidt
In this contribution, I give an overview of the various approaches toward the numerical modelling of turbulence, particularly, in the interstellar medium. The discussion is placed…
SUNRISE/IMaX observations of convectively driven vortex flows in the Sun
J. A. Bonet, I. Marquez, J. Sanchez Almeida +10
We characterize the observational properties of the convectively driven vortex flows recently discovered on the quiet Sun, using magnetograms, Dopplergrams and images obtained with…
Incommensurate spin correlations in highly oxidized cobaltates LaSrCoO
Z. W. Li, Y. Drees, C. Y. Kuo +13
We observe quasi-static incommensurate magnetic peaks in neutron scattering experiments on layered cobalt oxides La2-xSrxCoO4 with high Co oxidation states that have been reported…
Is magnetic reconnection the cause of supersonic upflows in granular cells ?
J. M. Borrero, V. Martinez Pillet, W. Schmidt +4
In a previous work, we reported on the discovery of supersonic magnetic upflows on granular cells in data from the {\sc Sunrise}/IMaX instrument. In the present work we investigate…
Hydrodynamical adaptive mesh refinement simulations of turbulent flows - I. Substructure in a wind
L. Iapichino, J. Adamek, W. Schmidt +1
The problem of the resolution of turbulent flows in adaptive mesh refinement (AMR) simulations is investigated by means of 3D hydrodynamical simulations in an idealised setup, repr…
Thermonuclear supernova simulations with stochastic ignition
W. Schmidt, J. C. Niemeyer
We apply an ad hoc model for dynamical ignition in three-dimensional numerical simulations of thermonuclear supernovae assuming pure deflagrations. The model makes use of the stati…
Bright points in the quiet Sun as observed in the visible and near-UV by the balloon-borne observatory Sunrise
T. L. Riethmueller, S. K. Solanki, V. MartÃnez Pillet +13
Bright points (BPs) are manifestations of small magnetic elements in the solar photosphere. Their brightness contrast not only gives insight into the thermal state of the photosphe…
Solenoidal versus compressive turbulence forcing
C. Federrath, J. Duval, R. S. Klessen +2
We analyze the statistics and star formation rate obtained in high-resolution numerical experiments of forced supersonic turbulence, and compare with observations. We concentrate o…
Deep probing of the photospheric sunspot penumbra: no evidence for magnetic field-free gaps
J. M. Borrero, A. Asensio Ramos, M. Collados +24
Some models for the topology of the magnetic field in sunspot penumbrae predict the existence of field-free or dynamically weak-field regions in the deep Photosphere. To confirm or…
A localised subgrid scale model for fluid dynamical simulations in astrophysics I: Theory and numerical tests
W. Schmidt, J. C. Niemeyer, W. Hillebrandt
We present a one-equation subgrid scale model that evolves the turbulence energy corresponding to unresolved velocity fluctuations in large eddy simulations. The model is derived i…
Absolute velocity measurements in sunspot umbrae
J. Löhner-Böttcher, W. Schmidt, R. Schlichenmaier +3
In sunspot umbrae, convection is largely suppressed by the strong magnetic field. Previous measurements reported on negligible convective flows in umbral cores. Based on this, nume…
Photospheric response to EB-like event
S. Danilovic, S. K. Solanki, P. Barthol +10
Ellerman Bombs are signatures of magnetic reconnection, which is an important physical process in the solar atmosphere. How and where they occur is a subject of debate. In this pap…
Algorithmic comparisons of decaying, isothermal, supersonic turbulence
S. Kitsionas, C. Federrath, R. Klessen +10
Contradicting results have been reported in the literature with respect to the performance of the numerical techniques employed for the study of supersonic turbulence. We aim at ch…
3D simulations of globules and pillars formation around HII regions: turbulence and shock curvature
P. Tremblin, E. Audit, V. Minier +2
We investigate the interplay between the ionization radiation from massive stars and the turbulence inside the surrounding molecular gas thanks to 3D numerical simulations. We used…
Turbulence production and turbulent pressure support in the intergalactic medium
L. Iapichino, W. Schmidt, J. C. Niemeyer +1
The injection and evolution of turbulence in the intergalactic medium is studied by means of mesh-based hydrodynamical simulations, including a subgrid scale (SGS) model for small-…
Direct assessment of SDO/HMI helioseismology of active regions on the Sun's far side using SO/PHI magnetograms
D. Yang, L. Gizon, H. Barucq +47
Earth-side observations of solar p modes can be used to image and monitor magnetic activity on the Sun's far side. Here we use magnetograms of the far side obtained by the Polarime…
Upper Chromospheric Magnetic Field of a Sunspot Penumbra: Observations of Fine Structure
J. Joshi, A. Lagg, S. K. Solanki +22
The fine-structure of magnetic field of a sunspot penumbra in the upper chromosphere is to be explored and compared to that in the photosphere. High spatial resolution spectropolar…
Field induced spin reorientation and giant spin-lattice coupling in EuFe2As2
Y. Xiao, Y. Su, W. Schmidt +11
We have studied a EuFe2As2 single crystal by neutron diffraction under magnetic fields up to 3.5 T and temperatures down to 2 K. A field induced spin reorientation is observed in t…
Observation of a short-lived pattern in the solar chromosphere
F. Wöger, S. Wedemeyer-Böhm, W. Schmidt +1
In this work we investigate the dynamic behavior of inter-network regions of the solar chromosphere. We observed the chromosphere of the quiet Sun using a narrow-band Lyot filter c…
Three-dimensional structure of a sunspot light bridge
T. Felipe, M. Collados, E. Khomenko +26
Active regions are the most prominent manifestations of solar magnetic fields; their generation and dissipation are fundamental problems in solar physics. Light bridges are commonl…
Inference of magnetic fields in the very quiet Sun
M. J. Mart\' inez González, A. Pastor Yabar, A. Lagg +29
We present high-precision spectro-polarimetric data with high spatial resolution (0.4) of the very quiet Sun at 1.56m obtained with the GREGOR telescope to shed some light…
Turbulence in a three-dimensional deflagration model for Type Ia supernovae: I. Scaling properties
F. Ciaraldi-Schoolmann, W. Schmidt, J. C. Niemeyer +2
We analyze the statistical properties of the turbulent velocity field in the deflagration model for Type Ia supernovae. In particular, we consider the question of whether turbulenc…
Influence of adaptive mesh refinement and the hydro solver on shear-induced mass stripping in a minor-merger scenario
W. Schmidt, J. Schulz, L. Iapichino +2
We compare two different codes for simulations of cosmological structure formation to investigate the sensitivity of hydrodynamical instabilities to numerics, in particular, the hy…
The Wave-Front Correction System for the Sunrise Balloon-Borne Solar Observatory
T. Berkefeld, W. Schmidt, D. Soltau +21
This paper describes the wave-front correction system developed for the Sunrise balloon telescope, and provides information about its in-flight performance. For the correction of l…
Detection of vortex tubes in solar granulation from observations with Sunrise
O. Steiner, M. Franz, N. Bello Gonzalez +11
We have investigated a time series of continuum intensity maps and corresponding Dopplergrams of granulation in a very quiet solar region at the disk center, recorded with the Imag…
The Polarimetric and Helioseismic Imager on Solar Orbiter
S. K. Solanki, J. C. del Toro Iniesta, J. Woch +121
This paper describes the Polarimetric and Helioseismic Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and helioseismology instrument to observe the Sun from o…
A new MHD-assisted Stokes inversion technique
T. L. Riethmüller, S. K. Solanki, P. Barthol +10
We present a new method of Stokes inversion of spectropolarimetric data and evaluate it by taking the example of a SUNRISE/IMaX observation. An archive of synthetic Stokes profiles…
Slender Ca II H Fibrils Mapping Magnetic Fields in the Low Solar Chromosphere
Shahin Jafarzadeh, R. J. Rutten, S. K. Solanki +14
A dense forest of slender bright fibrils near a small solar active region is seen in high-quality narrowband Ca II H images from the SuFI instrument onboard the Sunrise balloon-bor…
Water Production of Interstellar Comet 3I/ATLAS from SOHO/SWAN Observations after Perihelion
M. R. Combi, T. Mâkinen, J. -L. Bertaux +4
The Solar Wind ANisotropies (SWAN) all-sky hydrogen Lyman-alpha camera on the Solar and Heliosphere Observatory (SOHO) observed the hydrogen coma of interstellar comet 3I/ATLAS, al…
A Fluid-Dynamical Subgrid Scale Model for Highly Compressible Astrophysical Turbulence
W. Schmidt, C. Federrath
We formulate and implement the Euler equations with SGS dynamics and provide numerical tests of an SGS turbulence energy model that predicts the turbulent pressure of unresolved ve…
A localised subgrid scale model for fluid dynamical simulations in astrophysics II: Application to type Ia supernovae
W. Schmidt, J. C. Niemeyer, W. Hillebrandt +1
The dynamics of the explosive burning process is highly sensitive to the flame speed model in numerical simulations of type Ia supernovae. Based upon the hypothesis that the effect…
Magnetically driven superconductivity in CeCu2Si2
O. Stockert, J. Arndt, E. Faulhaber +8
The origin of unconventional superconductivity, including high-temperature and heavy-fermion superconductivity, is still a matter of controversy. Spin excitations instead of phonon…
Coronal voids and their magnetic nature
J. D. Nölke, S. K. Solanki, J. Hirzberger +68
Extreme ultraviolet (EUV) observations of the quiet solar atmosphere reveal extended regions of weak emission compared to the ambient quiescent corona. The magnetic nature of these…
Simulations of Turbulent Thermonuclear Burning in Type Ia Supernovae
W. Hillebrandt, M. Reinecke, W. Schmidt +3
Type Ia supernovae have recently received considerable attention because it appears that they can be used as "standard candles" to measure cosmic distances out to billions of light…
The signature of chromospheric heating in Ca II H spectra
C. Beck, W. Schmidt, R. Rezaei +1
We analyze a 1-hour time series of Ca II H intensity spectra and polarimetric spectra around 630 nm to derive the signature of the chromospheric heating and to investigate its rela…
LARS - An Absolute Reference Spectrograph for solar observations, Upgrade from a prototype to a turn-key system
J. Loehner-Boettcher, W. Schmidt, H. -P. Doerr +4
LARS is an Absolute Reference Spectrograph designed for ultra-precise solar observations. The high-resolution echelle spectrograph of the Vacuum Tower Telescope is supported by a s…
Magnetic fields of opposite polarity in sunspot penumbrae
M. Franz, M. Collados, C. Bethge +25
Context. A significant part of the penumbral magnetic field returns below the surface in the very deep photosphere. For lines in the visible, a large portion of this return field c…
Photospheric Magnetic Fields of the Trailing Sunspots in Active Region NOAA 12396
M. Verma, H. Balthasar, C. Denker +27
The solar magnetic field is responsible for all aspects of solar activity. Sunspots are the main manifestation of the ensuing solar activity. Combining high-resolution and synoptic…
Antiferromagnetic correlations in the metallic strongly correlated transition metal oxide LaNiO
H. Guo, Z. W. Li, L. Zhao +10
The material class of rare earth nickelates with high Ni oxidation state is generating continued interest due to the occurrence of a metal-insulator transition with charge o…
The on-ground data reduction and calibration pipeline for SO/PHI-HRT
J. Sinjan, D. Calchetti, J. Hirzberger +47
The ESA/NASA Solar Orbiter space mission has been successfully launched in February 2020. Onboard is the Polarimetric and Helioseismic Imager (SO/PHI), which has two telescopes, a…
Unnoticed magnetic field oscillations in the very quiet Sun revealed by Sunrise/IMaX
M. J. Martinez Gonzalez, A. Asensio Ramos, R. Manso Sainz +7
We present observational evidence for oscillations of magnetic flux density in the quiet areas of the Sun. The majority of magnetic fields on the solar surface have strengths of th…
Neutron inelastic scattering study of rare-earth orthoferrite HoFeO
A. K. Ovsyanikov, I. A. Zobkalo, W. Schmidt +3
By the single crystal inelastic neutron scattering the orthoferrite HoFeO3 was studied. We show that the spin dynamics of the Fe subsystem does not change through the spin-reorient…
Turbulence modeling and the physics of the intra-cluster medium
L. Iapichino, A. Maier, W. Schmidt +1
FEARLESS (Fluid mEchanics with Adaptively Refined Large Eddy SimulationS) is a new numerical scheme arising from the combined use of subgrid scale (SGS) model for turbulence at the…
The characteristic black hole mass resulting from direct collapse in the early universe
M. A. Latif, D. R. G. Schleicher, W. Schmidt +1
Black holes of a billion solar masses are observed in the infant universe a few hundred million years after the Big Bang. The direct collapse of protogalactic gas clouds in primord…
Cosmological Fluid Mechanics with Adaptively Refined Large Eddy Simulations
W. Schmidt, A. S. Almgren, H. Braun +6
We investigate turbulence generated by cosmological structure formation by means of large eddy simulations using adaptive mesh refinement. In contrast to the widely used implicit l…
Relation between photospheric magnetic field and chromospheric emission
R. Rezaei, R. Schlichenmaier, C. A. R. Beck +2
We simultaneously observed the Stokes parameters of the photospheric iron line pair at 630.2 nm and the intensity profile of the chromospheric Ca II H line at 396.8 nm in a quiet S…
Forced turbulence in thermally bistable gas: A parameter study
D. Seifried, W. Schmidt, J. C. Niemeyer
Context: The thermal instability is one of the dynamical agents for turbulence in the diffuse interstellar medium, where both, turbulence and thermal instability interact in a high…
Slipping reconnection in a solar flare observed in high resolution with the GREGOR solar telescope
M. Sobotka, J. DudÃk, C. Denker +23
A small flare ribbon above a sunspot umbra in active region 12205 was observed on November 7, 2014, at 12:00 UT in the blue imaging channel of the 1.5 m GREGOR telescope, using a 1…
The Filter Imager SuFI and the Image Stabilization and Light Distribution System ISLiD of the Sunrise Balloon-Borne Observatory: Instrument Description
A. Gandorfer, B. Grauf, P. Barthol +29
We describe the design of the Sunrise Filter Imager (SuFI) and the Image Stabilization and Light Distribution (ISLiD) unit onboard the Sunrise balloon borne solar observatory. This…
Magnetic anisotropic energy gap and low energy spin wave excitation in antiferromagnetic block phase of K2Fe4Se5
Y. Xiao, S. Nandi, Y. Su +11
Neutron scattering experiments were performed to investigate magnetic order and magnetic excitations in ternary iron chalcogenide K2Fe4Se5. The formation of a superlattice structur…
Spectropolarimetric observations of an arch filament system with the GREGOR solar telescope
H. Balthasar, P. Gömöry, S. J. González Manrique +27
Arch filament systems occur in active sunspot groups, where a fibril structure connects areas of opposite magnetic polarity, in contrast to active region filaments that follow the…
Level set simulations of turbulent thermonuclear deflagration in degenerate carbon and oxygen
W. Schmidt, W. Hillebrandt, J. C. Niemeyer
We study the dynamics of thermonuclear flames propagating in fuel stirred by stochastic forcing. The fuel consists of carbon and oxygen in a state which is encountered in white dwa…
Thermonuclear explosions of rapidly rotating white dwarfs - II. Detonations
J. M. M. Pfannes, J. C. Niemeyer, W. Schmidt
Context: Superluminous type Ia supernovae (SNe Ia) may be explained by super-Chandrasekhar-mass explosions of rapidly rotating white dwarfs (WDs). In a preceding paper, we showed t…
Turbulence in a 3D deflagration model for type Ia SNe: II. Intermittency and the deflagration-to-detonation transition probability
W. Schmidt, F. Ciaraldi-Schoolmann, J. C. Niemeyer +2
The delayed detonation model describes the observational properties of the majority of type Ia supernovae very well. Using numerical data from a three-dimensional deflagration mode…
Morphological properties of slender Ca II H fibrils observed by SUNRISE II
R. Gafeira, A. Lagg, Sami K Solanki +12
We use seeing-free high spatial resolution Ca II H data obtained by the SUNRISE observatory to determine properties of slender fibrils in the lower solar chromosphere. In this work…
The ratio of horizontal to vertical displacement in solar oscillations estimated from combined SO/PHI and SDO/HMI observations
J. Schou, J. Hirzberger, D. Orozco Suárez +44
In order to make accurate inferences about the solar interior using helioseismology, it is essential to understand all the relevant physical effects on the observations. One effect…
Spectropolarimetric evidence for a siphon flow along an emerging magnetic flux tube
Iker S. Requerey, B. Ruiz Cobo, J. C. Del Toro Iniesta +12
We study the dynamics and topology of an emerging magnetic flux concentration using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperime…
Charge disproportionation and nano phase separation in SrNiO
H. Guo, Z. W. Li, C. F. Chang +16
We have successfully grown centimeter-sized layered SrNiO single crystals under high oxygen pressures of 120 bar by the floating zone technique. This enabled us to perform n…
Comparing the statistics of interstellar turbulence in simulations and observations: Solenoidal versus compressive turbulence forcing
C. Federrath, J. Roman-Duval, R. Klessen +2
We study two limiting cases of turbulence forcing in numerical experiments: solenoidal (divergence-free) forcing, and compressive (curl-free) forcing, and compare our results to ob…
Supersonic Magnetic Flows in the Quiet Sun
J. M. Borrero, V. Martinez Pillet, R. Schlichenmaier +8
In this contribution we describe some recent observations of high-speed magnetized flows in the quiet Sun granulation. These observations were carried out with the Imaging Magnetog…
GREGOR: the New German Solar Telescope
H. Balthasar, O. von der Lühe, F. Kneer +17
GREGOR is a new open solar telescope with an aperture of 1.5m. It replaces the former 45-cm Gregory Coude telescope on the Canary island Tenerife. The optical concept is that of a…
New PAH mode at 16.4 microns
C. Moutou, L. Verstraete, A. Leger +2
The detection of a new 16.4 micron emission feature in the ISO-SWS spectra of NGC 7023, M17, and the Orion Bar is reported. Previous laboratory experiments measured a mode near thi…
Chiral Order and Multiferroic Domain Relaxation in NaFeGeO
S. Biesenkamp, D. Gorkov, W. Schmidt +5
The magnetic structure and the multiferroic relaxation dynamics of NaFeGeO were studied by neutron scattering on single crystals partially utilizing polarization analysis.…
Spectropolarimetric Observations of an Arch Filament System with GREGOR
H. Balthasar, P. Gömöry, S. J. González Manrique +16
We observed an arch filament system (AFS) in a sunspot group with the GREGOR Infrared Spectrograph attached to the GREGOR solar telescope. The AFS was located between the leading s…
Power spectrum of turbulent convection in the solar photosphere
L. Yelles Chaouche, R. H. Cameron, S. K. Solanki +15
The solar photosphere provides us with a laboratory for understanding turbulence in a layer where the fundamental processes of transport vary rapidly and a strongly superadiabatic…
Fitting peculiar spectral profiles in He I 10830 Ã absorption features
S. J. González Manrique, C. Kuckein, A. Pastor Yabar +28
The new generation of solar instruments provides better spectral, spatial, and temporal resolution for a better understanding of the physical processes that take place on the Sun.…
Intensity contrast of solar network and faculae close to the solar limb, observed from two vantage points
K. Albert, N. A. Krivova, J. Hirzberger +43
The brightness of faculae and network depends on the angle at which they are observed and the magnetic flux density. Close to the limb, assessment of this relationship has until no…
Highly Dispersive Spin Excitations in the Chain Cuprate Li2CuO2
W. E. A. Lorenz, R. O. Kuzian, S. -L. Drechsler +11
We present an inelastic neutron scattering investigation of Li2CuO2 detecting the long sought quasi-1D magnetic excitations with a large dispersion along the CuO2-chains studied up…
On self-similarity properties of isotropic turbulence in numerical simulations of the compressible Euler equations
W. Schmidt, W. Hillebrandt, J. C. Niemeyer
We present numerical calculations of the parameters , and associated with the common closures for turbulence production, dissipation and diffusion. In the case…
Supersonic Magnetic Upflows in Granular Cells Observed with Sunrise/IMaX
J. M. Borrero, V. Martinez Pillet, R. Schlichenmaier +8
Using the IMaX instrument on-board the Sunrise stratospheric balloon-telescope we have detected extremely shifted polarization signals around the Fe I 5250.217 Ã spectral line with…
Oscillations on width and intensity of slender Ca II H fibrils from Sunrise/SuFI
R. Gafeira, S. Jafarzadeh, S. K. Solanki +12
We report the detection of oscillations in slender Ca II H fibrils (SCFs) from high-resolution observations acquired with the Sunrise balloon-borne solar observatory. The SCFs show…
Local support against gravity in magneto-turbulent fluids
W. Schmidt, D. C. Collins, A. G. Kritsuk
Comparisons of the integrated thermal pressure support of gas against its gravitational potential energy lead to critical mass scales for gravitational instability such as the Jean…
Magnetically induced Ferroelectricity in BiCuO
L. Zhao, H. Guo, W. Schmidt +3
The tetragonal copper oxide BiCuO has an unusual crystal structure with a three-dimensional network of well separated CuO plaquettes. This material was recently predict…
Resolving the internal magnetic structure of the solar network
M. J. MartÃnez González, L. R. Bellot Rubio, S. K. Solanki +4
We analyze the spectral asymmetry of Stokes V (circularly polarized) profiles of an individual network patch in the quiet Sun observed by Sunrise/IMaX. At a spatial resolution of 0…
Temporal evolution of magnetic elements
R. Rezaei, R. Schlichenmaier, W. Schmidt +1
We study the structure and evolution of the magnetic field of the quiet Sun by investigating weak spectro-polarimetric signals. To this end, we observed a quiet region close to the…
The structure of the thermally bistable and turbulent atomic gas in the local interstellar medium
E. Saury, M. -A. Miville-Deschênes, P. Hennebelle +2
This paper is a numerical study of the condensation of the warm neutral medium (WNM) into cold neutral medium (CNM) structures under the effect of turbulence and thermal instabilit…
Coexistence of Eu-antiferromagnetism and pressure-induced superconductivity in EuFe2As2 single crystal
W. T. Jin, Y. Xiao, S. Nandi +7
By performing high-pressure single-crystal neutron diffraction measurements, the evolution of structure and magnetic ordering in EuFe2As2 under hydrostatic pressure were investigat…
Hour-glass magnetic excitations induced by nanoscopic phase separation in cobalt oxides LaSrCoO
Y. Drees, Z. W. Li, A. Ricci +10
The magnetic excitations in the cuprate superconductors might be essential for an understanding of high-temperature superconductivity. In these cuprate superconductors the magnetic…
A three-dimensional deflagration model for Type Ia supernovae confronted with observations
F. K. Roepke, W. Hillebrandt, W. Schmidt +3
A simulation of the thermonuclear explosion of a Chandrasekhar-mass C+O white dwarf, the most popular scenario of a type Ia supernova (SN Ia), is presented. The underlying modeling…
Magnetic structure of the Eu2+ moments in superconducting EuFe2(As1-xPx)2 with x = 0.19
S. Nandi, W. T. Jin, Y. Xiao +8
The magnetic structure of the Eu2+ moments in the superconducting EuFe2(As1-xPx)2 sample with x = 0.19 has been determined using neutron scattering. We conclude that the Eu2+ momen…
The small scale dynamo and the amplification of magnetic fields in massive primordial haloes
M. A. Latif, D. R. G. Schleicher, W. Schmidt +1
While present standard model of cosmology yields no clear prediction for the initial magnetic field strength, efficient dynamo action may compensate for initially weak seed fields…
Opposite magnetic polarity of two photospheric lines in single spectrum of the quiet Sun
R. Rezaei, R. Schlichenmaier, W. Schmidt +1
We study the structure of the photospheric magnetic field of the quiet Sun by investigating weak spectro-polarimetric signals. We took a sequence of Stokes spectra of the Fe I 630.…
Moving Magnetic Features around a Pore
A. J. Kaithakkal, T. L. Riethmüller, S. K. Solanki +12
Spectropolarimetric observations from Sunrise II/IMaX obtained in June 2013 are used for a statistical analysis to determine the physical properties of moving magnetic features (MM…
Turbulence Modelling and Stirring Mechanisms in the Cosmological Large-scale Structure
L. Iapichino, W. Schmidt, J. C. Niemeyer +1
FEARLESS (Fluid mEchanics with Adaptively Refined Large Eddy SimulationS) is a numerical scheme for modelling subgrid-scale turbulence in cosmological adaptive mesh refinement simu…
Control of chiral magnetism in multiferroic MnWO4 through an electric field
T. Finger, D. Senff, K. Schmalzl +5
The chiral components in the magnetic order in multiferroic MnWO4 have been studied by neutron diffraction using spherical polarization analysis as a function of temperature and of…
Magneto-static modelling from SUNRISE/IMaX: Application to an active region observed with SUNRISE II
T. Wiegelmann, T. Neukirch, D. H. Nickeler +13
Magneto-static models may overcome some of the issues facing force-free magnetic field extrapolations. So far they have seen limited use and have faced problems when applied to qui…
Fully resolved quiet-Sun magnetic flux tube observed with the Sunrise IMaX instrument
A. Lagg, S. K. Solanki, T. L. Riethmueller +14
Until today, the small size of magnetic elements in quiet Sun areas has required the application of indirect methods, such as the line-ratio technique or multi-component inversions…
The magnetic drivers of campfires seen by the Polarimetric and Helioseismic Imager (PHI) on Solar Orbiter
F. Kahil, J. Hirzberger, S. K. Solanki +56
The Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter (SO) spacecraft observed small extreme ultraviolet (EUV) bursts, termed campfires, that have been proposed to be bri…
Kinematics of Magnetic Bright Features in the Solar Photosphere
Shahin Jafarzadeh, S. K. Solanki, R. H. Cameron +12
Convective flows are known as the prime means of transporting magnetic fields on the solar surface. Thus, small magnetic structures are good tracers of the turbulent flows. We stud…
Magnetic fields during the formation of supermassive black holes
M. A. Latif, D. R. G. Schleicher, W. Schmidt
Observations of quasars at report the existence of a billion solar mass black holes. Comprehending their formation in such a short time scale is a matter of ongoing rese…
High resolution studies of massive primordial haloes
M. A. Latif, D. R. G. Schleicher, W. Schmidt +1
Atomic cooling haloes with virial temperatures K are the most plausible sites for the formation of the first galaxies and the first intermediate mass blac…
Black hole formation in the early universe
M. A. Latif, D. R. G. Schleicher, W. Schmidt +1
Supermassive black holes with up to a dwell in the centers of present-day galaxies, and their presence has been confirmed at z 6. Their formation at s…
New grids of ATLAS9 atmospheres I: Influence of convection treatments on model structure and on observable quantities
U. Heiter, F. Kupka, C. van 't Veer-Menneret +6
We present several new sets of grids of model stellar atmospheres computed with modified versions of the ATLAS9 code. Each individual set consists of several grids of models with d…
Adaptively refined large eddy simulations of clusters
A. Maier, L. Iapichino, W. Schmidt +1
We present a numerical scheme for modelling unresolved turbulence in cosmological adaptive mesh refinement codes. As a first application, we study the evolution of turbulence in th…
The photospheric solar oxygen project: III. Investigation of the centre-to-limb variation of the 630nm [OI]-NiI blend
E. Caffau, H. -G. Ludwig, M. Steffen +5
The solar photospheric abundance of oxygen is still a matter of debate. For about ten years some determinations have favoured a low oxygen abundance which is at variance with the v…