H. Schunker
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View article: The impact of rotational mixing in intermediate-age star clusters with extended main-sequence turn-offs and extended red clumps
The impact of rotational mixing in intermediate-age star clusters with extended main-sequence turn-offs and extended red clumps Open
The extended main-sequence turn-offs (eMSTOs) and extended red clumps (eRCs) observed in intermediate-age star clusters challenge the traditional understanding of clusters as simple stellar populations. Recently, eMSTOs have been interpret…
View article: The impact of rotational mixing in intermediate-age star clusters with extended main-sequence turn-offs and extended red clumps
The impact of rotational mixing in intermediate-age star clusters with extended main-sequence turn-offs and extended red clumps Open
The extended main-sequence turn-offs (eMSTOs) and extended red clumps (eRCs) observed in intermediate-age star clusters challenge the traditional understanding of clusters as simple stellar populations. Recently, eMSTOs have been interpret…
View article: Closing the solar dynamo loop: Poloidal field generated at the surface by plasma flows
Closing the solar dynamo loop: Poloidal field generated at the surface by plasma flows Open
Context. The large-scale magnetic field of the Sun is produced by dynamo action due to convection and rotation. The toroidal magnetic field is maintained by the Sun’s differential rotation that winds up the azimuthally averaged radial and …
View article: Coriolis force acting on near-surface horizontal flows during simulations of flux emergence produces a tilt angle consistent with Joy’s law on the Sun
Coriolis force acting on near-surface horizontal flows during simulations of flux emergence produces a tilt angle consistent with Joy’s law on the Sun Open
Context. Joy’s law describes the tilt of bipolar active regions on the Sun away from an east-west orientation, where the flux of the polarity concentrated at the prograde side tends to be closer to the equator than the polarity on the retr…
View article: The Sun’s Open–Closed Flux Boundary and the Origin of the Slow Solar Wind
The Sun’s Open–Closed Flux Boundary and the Origin of the Slow Solar Wind Open
The Sun’s open–closed flux boundary (OCB) separates closed and open magnetic field lines, and is the site for interchange magnetic reconnection processes thought to be linked to the origin of the slow solar wind (SSW). We analyze the globa…
View article: A flux-independent increase in outflows prior to the emergence of active regions on the Sun
A flux-independent increase in outflows prior to the emergence of active regions on the Sun Open
Emerging active regions are associated with convective flows on the spatial scale and lifetimes of supergranules. To understand how these flows are involved in the formation of active regions, we aim to identify where active regions emerge…
View article: A flux-independent increase in outflows prior to the emergence of active regions on the Sun
A flux-independent increase in outflows prior to the emergence of active regions on the Sun Open
Emerging active regions are associated with convective flows on the spatial scale and lifetimes of supergranules. To understand how these flows are involved in the formation of active regions, we aim to identify where active regions emerge…
View article: Firefly: The Case for a Holistic Understanding of the Global Structure and Dynamics of the Sun and the Heliosphere
Firefly: The Case for a Holistic Understanding of the Global Structure and Dynamics of the Sun and the Heliosphere Open
status: Published
View article: Improved Observational Coverage of the Solar Magnetic Field
Improved Observational Coverage of the Solar Magnetic Field Open
Whitepaper #062 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: space weather applications; basic research. Additional topics: space weather research/operations/research loop; ground-based missions/…
View article: Understanding Active Region Emergence and Origins on the Sun and Other Cool Stars
Understanding Active Region Emergence and Origins on the Sun and Other Cool Stars Open
The emergence of active regions on the Sun is an integral feature of the solar dynamo mechanism. However, details about the generation of active-region-scale magnetism and the journey of this magnetic flux to the photosphere are still in q…
View article: Evolution of the magnetic field and flows of solar active regions with persistent magnetic bipoles before emergence
Evolution of the magnetic field and flows of solar active regions with persistent magnetic bipoles before emergence Open
Magnetic active regions on the Sun are harbingers of space weather. Understanding the physics of how they form and evolve will improve space weather forecasting. Our aim is to characterise the surface magnetic field and flows for a sample …
View article: Impact of spatially correlated fluctuations in sunspots on metrics related to magnetic twist
Impact of spatially correlated fluctuations in sunspots on metrics related to magnetic twist Open
Context. The twist of the magnetic field above a sunspot is an important quantity in solar physics. For example, magnetic twist plays a role in the initiation of flares and coronal mass ejections (CMEs). Various proxies for the twist above…
View article: Testing solar surface flux transport models in the first days after active region emergence
Testing solar surface flux transport models in the first days after active region emergence Open
Context. Active regions (ARs) play an important role in the magnetic dynamics of the Sun. Solar surface flux transport models (SFTMs) are used to describe the evolution of the radial magnetic field at the solar surface. The models are kine…
View article: Testing solar surface flux transport models in the first days after active region emergence
Testing solar surface flux transport models in the first days after active region emergence Open
Active regions (ARs) play an important role in the magnetic dynamics of the Sun. Solar surface flux transport models (SFTMs) are used to describe the evolution of the radial magnetic field at the solar surface. There is however uncertainty…
View article: Evolution of solar surface inflows around emerging active regions
Evolution of solar surface inflows around emerging active regions Open
Context. Solar active regions are associated with Evershed outflows in sunspot penumbrae, moat outflows surrounding sunspots, and extended inflows surrounding active regions. Extended inflows have been identified around established active …
View article: Importance of convection for emerging active regions on the Sun
Importance of convection for emerging active regions on the Sun Open
The emergence of magnetic field from the interior of the Sun generates a poloidal magnetic field from rising toroidal magnetic field. Solar active regions and sunspots are the strongest concentrations of magnetic field on the surface, and …
View article: Local helioseismology within surface magnetic fields
Local helioseismology within surface magnetic fields Open
This thesis was scanned from the print manuscript for digital preservation and is copyright the author. Researchers can access this thesis by asking their local university, institution or public library to make a request on their behalf. M…
View article: Average motion of emerging solar active region polarities
Average motion of emerging solar active region polarities Open
Context. The tilt of solar active regions described by Joy’s law is essential for converting a toroidal field to a poloidal field in Babcock-Leighton dynamo models. In thin flux tube models the Coriolis force causes what we observe as Joy’…
View article: Average surface flows before the formation of solar active regions and their relationship to the supergranulation pattern
Average surface flows before the formation of solar active regions and their relationship to the supergranulation pattern Open
Context . The emergence of solar active regions is an important but poorly understood aspect of the solar dynamo. Aims . Knowledge of the flows associated with the rise of active-region-forming magnetic concentrations through the near-surf…
View article: Observing and modeling the poloidal and toroidal fields of the solar dynamo
Observing and modeling the poloidal and toroidal fields of the solar dynamo Open
Context. The solar dynamo consists of a process that converts poloidal magnetic field to toroidal magnetic field followed by a process that creates new poloidal field from the toroidal field. Aims. Our aim is to observe the poloidal and to…
View article: Limits on radial differential rotation in Sun-like stars from parametric fits to oscillation power spectra
Limits on radial differential rotation in Sun-like stars from parametric fits to oscillation power spectra Open
\n Context. Rotational shear in Sun-like stars is thought to be an important ingredient in models of stellar dynamos. Thanks to helioseismology, rotation in the Sun is characterized well, but the interior rotation profiles of other Sun-lik…
View article: SDO/HMI survey of emerging active regions for helioseismology
SDO/HMI survey of emerging active regions for helioseismology Open
Context. Observations from the Solar Dynamics Observatory (SDO) have the potential for allowing the helioseismic study of the formation of hundreds of active regions, which would enable us to perform statistical analyses. Aims. Our goal is…
View article: A low upper limit on the subsurface rise speed of solar active regions
A low upper limit on the subsurface rise speed of solar active regions Open
Comparison of observations and simulations provides a strong upper limit on the subsurface rise speed of solar active regions.