All Outputs (78)

Reconstructing solar magnetic fields from historical observations (2017)
Journal Article
Virtanen, I., Virtanen, I., Pevtsov, A., Yeates, A., & Mursula, K. (2017). Reconstructing solar magnetic fields from historical observations. Astronomy & Astrophysics, 604, Article A8. https://doi.org/10.1051/0004-6361/201730415

Aims. We aim to use the surface flux transport model to simulate the long-term evolution of the photospheric magnetic field from historical observations. In this work we study the accuracy of the model and its sensitivity to uncertainties in its main... Read More about Reconstructing solar magnetic fields from historical observations.

Sparse reconstruction of electric fields from radial magnetic data (2017)
Journal Article
Yeates, A. (2017). Sparse reconstruction of electric fields from radial magnetic data. Astrophysical Journal, 836(1), Article 131. https://doi.org/10.3847/1538-4357/aa5c84

Accurate estimates of the horizontal electric field on the Sun's visible surface are important not only for estimating the Poynting flux of magnetic energy into the corona but also for driving time-dependent magnetohydrodynamic models of the corona.... Read More about Sparse reconstruction of electric fields from radial magnetic data.

The global distribution of magnetic helicity in the solar corona (2016)
Journal Article
Yeates, A., & Hornig, G. (2016). The global distribution of magnetic helicity in the solar corona. Astronomy & Astrophysics, 594, Article A98. https://doi.org/10.1051/0004-6361/201629122

By defining an appropriate field line helicity, we apply the powerful concept of magnetic helicity to the problem of global magnetic field evolution in the Sun's corona. As an ideal-magnetohydrodynamic invariant, the field line helicity is a meaningf... Read More about The global distribution of magnetic helicity in the solar corona.

The Possible Impact of L5 Magnetograms on Non-Potential Solar Coronal Magnetic Field Simulations (2016)
Journal Article
Weinzierl, M., Mackay, D. H., Yeates, A. R., & Pevtsov, A. A. (2016). The Possible Impact of L5 Magnetograms on Non-Potential Solar Coronal Magnetic Field Simulations. Astrophysical Journal, 828(2), Article 102. https://doi.org/10.3847/0004-637x/828/2/102

The proposed Carrington-L5 mission would bring instruments to the L5 Lagrange point to provide us with crucial data for space weather prediction. To assess the importance of including a magnetograph, we consider the possible differences in non-potent... Read More about The Possible Impact of L5 Magnetograms on Non-Potential Solar Coronal Magnetic Field Simulations.

A New Technique for the Photospheric Driving of Non-Potential Solar Coronal Magnetic Field Simulations (2016)
Journal Article
Weinzierl, M., Yeates, A. R., Mackay, D. H., Henney, C. J., & Arge, C. N. (2016). A New Technique for the Photospheric Driving of Non-Potential Solar Coronal Magnetic Field Simulations. Astrophysical Journal, 823(1), Article 55. https://doi.org/10.3847/0004-637x/823/1/55

In this paper, we develop a new technique for driving global non-potential simulations of the Sun's coronal magnetic field solely from sequences of radial magnetic maps of the solar photosphere. A primary challenge to driving such global simulations... Read More about A New Technique for the Photospheric Driving of Non-Potential Solar Coronal Magnetic Field Simulations.

Stellar coronal response to differential rotation and flux emergence (2016)
Journal Article
Gibb, G., Mackay, D., Jardine, M., & Yeates, A. (2016). Stellar coronal response to differential rotation and flux emergence. Monthly Notices of the Royal Astronomical Society, 456(4), 3624-3637. https://doi.org/10.1093/mnras/stv2920

We perform a numerical parameter study to determine what effect varying differential rotation and flux emergence has on a star's non-potential coronal magnetic field. In particular we consider the effects on the star's surface magnetic flux, open mag... Read More about Stellar coronal response to differential rotation and flux emergence.

Influence of Non-Potential Coronal Magnetic Topology on Solar-Wind Models (2015)
Journal Article
Edwards, S., Yeates, A., Bocquet, F., & Mackay, D. (2015). Influence of Non-Potential Coronal Magnetic Topology on Solar-Wind Models. Solar Physics, 290(10), 2791-2808. https://doi.org/10.1007/s11207-015-0795-8

By comparing a magneto-frictional model of the low-coronal magnetic-field to a potential-field source-surface model, we investigate the possible impact of non-potential magnetic structure on empirical solar-wind models. These empirical models (such a... Read More about Influence of Non-Potential Coronal Magnetic Topology on Solar-Wind Models.

Physical role of topological constraints in localized magnetic relaxation (2015)
Journal Article
Yeates, A., Russell, A., & Hornig, G. (2015). Physical role of topological constraints in localized magnetic relaxation. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 471(2178), Article 20150012. https://doi.org/10.1098/rspa.2015.0012

Predicting the final state of turbulent plasma relaxation is an important challenge, both in astro-physical plasmas such as the Sun's corona and in controlled thermonuclear fusion. Recent numerical simulations of plasma relaxation with braided magnet... Read More about Physical role of topological constraints in localized magnetic relaxation.

Evolution of field line helicity during magnetic reconnection (2015)
Journal Article
Russell, A., Yeates, A., Hornig, G., & Wilmot-Smith, A. (2015). Evolution of field line helicity during magnetic reconnection. Physics of Plasmas, 22(3), Article 032106. https://doi.org/10.1063/1.4913489

We investigate the evolution of field line helicity for magnetic fields that connect two boundaries without null points, with emphasis on localized finite-B magnetic reconnection. Total (relative) magnetic helicity is already recognized as an importa... Read More about Evolution of field line helicity during magnetic reconnection.

Source of a Prominent Poleward Surge During Solar Cycle 24 (2015)
Journal Article
Yeates, A., Baker, D., & van Driel-Gesztelyi, L. (2015). Source of a Prominent Poleward Surge During Solar Cycle 24. Solar Physics, 290(11), 3189-3201. https://doi.org/10.1007/s11207-015-0660-9

As an observational case study, we consider the origin of a prominent poleward surge of leading polarity, visible in the magnetic butterfly diagram during Solar Cycle 24. A new technique is developed for assimilating individual regions of strong magn... Read More about Source of a Prominent Poleward Surge During Solar Cycle 24.

Small-scale and global dynamos and the area and flux distributions of active regions, sunspot groups, and sunspots : a multi-database study (2015)
Journal Article
Muñoz-Jaramillo, A., Senkpeil, R., Windmueller, J., Amouzou, E., Longcope, D., Tlatov, A., …Martens, P. (2015). Small-scale and global dynamos and the area and flux distributions of active regions, sunspot groups, and sunspots : a multi-database study. Astrophysical Journal, 800(1), Article 48. https://doi.org/10.1088/0004-637x/800/1/48

In this work, we take advantage of 11 different sunspot group, sunspot, and active region databases to characterize the area and flux distributions of photospheric magnetic structures. We find that, when taken separately, different databases are bett... Read More about Small-scale and global dynamos and the area and flux distributions of active regions, sunspot groups, and sunspots : a multi-database study.

A complete topological invariant for braided magnetic fields (2014)
Journal Article
Yeates, A., & Hornig, G. (2014). A complete topological invariant for braided magnetic fields. Journal of Physics: Conference Series, 544(1), Article 012002. https://doi.org/10.1088/1742-6596/544/1/012002

A topological flux function is introduced to quantify the topology of magnetic braids: non-zero line-tied magnetic fields whose field lines all connect between two boundaries. This scalar function is an ideal invariant defined on a cross-section of t... Read More about A complete topological invariant for braided magnetic fields.

Observations of a hybrid double-streamer/pseudostreamer in the solar corona (2014)
Journal Article
Rachmeler, L., Platten, S., Bethge, C., Seaton, D., & Yeates, A. (2014). Observations of a hybrid double-streamer/pseudostreamer in the solar corona. Astrophysical Journal Letters, 787(1), https://doi.org/10.1088/2041-8205/787/1/l3

We report on the first observation of a single hybrid magnetic structure that contains both a pseudostreamer and a double streamer. This structure was originally observed by the SWAP instrument on board the PROBA2 satellite between 2013 May 5 and 10.... Read More about Observations of a hybrid double-streamer/pseudostreamer in the solar corona.

On the helicity of open magnetic fields (2014)
Journal Article
Prior, C., & Yeates, A. (2014). On the helicity of open magnetic fields. Astrophysical Journal, 787(2), Article 100. https://doi.org/10.1088/0004-637x/787/2/100

We reconsider the topological interpretation of magnetic helicity for magnetic fields in open domains, and relate this to the relative helicity. Specifically, our domains stretch between two parallel planes, and each of these ends may be magnetically... Read More about On the helicity of open magnetic fields.

The coronal energy input from magnetic braiding (2014)
Journal Article
Yeates, A., Bianchi, F., Welsh, B., & Bushby, P. (2014). The coronal energy input from magnetic braiding. Astronomy & Astrophysics, 564, Article A131. https://doi.org/10.1051/0004-6361/201323276

We estimate the energy input into the solar corona from photospheric footpoint motions, using observations of a plage region by the Hinode Solar Optical Telescope. Assuming a perfectly ideal coronal evolution, two alternative lower bounds for the Poy... Read More about The coronal energy input from magnetic braiding.

Detection of coherent structures in photospheric turbulent flows (2014)
Journal Article
Chian, A., Rempel, E., Aulanier, G., Schmieder, B., Shadden, S., Welsch, B., & Yeates, A. (2014). Detection of coherent structures in photospheric turbulent flows. Astrophysical Journal, 786(1), https://doi.org/10.1088/0004-637x/786/1/51

We study coherent structures in solar photospheric flows in a plage in the vicinity of the active region AR 10930 using the horizontal velocity data derived from Hinode/Solar Optical Telescope magnetograms. Eulerian and Lagrangian coherent structures... Read More about Detection of coherent structures in photospheric turbulent flows.

Kinematic active region formation in a three-dimensional solar dynamo model (2013)
Journal Article
Yeates, A., & Munoz-Jaramillo, A. (2013). Kinematic active region formation in a three-dimensional solar dynamo model. Monthly Notices of the Royal Astronomical Society, 436(4), 3366-3379. https://doi.org/10.1093/mnras/stt1818

We propose a phenomenological technique for modelling the emergence of active regions within a three-dimensional, kinematic dynamo framework. By imposing localized velocity perturbations, we create emergent flux tubes out of toroidal magnetic field a... Read More about Kinematic active region formation in a three-dimensional solar dynamo model.

Coronal Magnetic Field Evolution from 1996 to 2012: Continuous Non-potential Simulations (2013)
Journal Article
Yeates, A. (2014). Coronal Magnetic Field Evolution from 1996 to 2012: Continuous Non-potential Simulations. Solar Physics, 289(2), 631-648. https://doi.org/10.1007/s11207-013-0301-0

Coupled flux transport and magneto-frictional simulations are extended to simulate the continuous magnetic-field evolution in the global solar corona for over 15 years, from the start of Solar Cycle 23 in 1996. By simplifying the dynamics, our model... Read More about Coronal Magnetic Field Evolution from 1996 to 2012: Continuous Non-potential Simulations.

Pathways of Large-scale Magnetic Couplings Between Solar Coronal Events (2013)
Journal Article
Schrijver, C., Title, A., Yeates, A., & DeRosa, M. (2013). Pathways of Large-scale Magnetic Couplings Between Solar Coronal Events. Astrophysical Journal, 773(2), https://doi.org/10.1088/0004-637x/773/2/93

The high-cadence, comprehensive view of the solar corona by SDO/AIA shows many events that are widely separated in space while occurring close together in time. In some cases, sets of coronal events are evidently causally related, while in many other... Read More about Pathways of Large-scale Magnetic Couplings Between Solar Coronal Events.

Unique topological characterization of braided magnetic fields (2013)
Journal Article
Yeates, A., & Hornig, G. (2013). Unique topological characterization of braided magnetic fields. Physics of Plasmas, 20(1), Article 012102. https://doi.org/10.1063/1.4773903

We introduce a topological flux function to quantify the topology of magnetic braids: non-zero, line-tied magnetic fields whose field lines all connect between two boundaries. This scalar function is an ideal invariant defined on a cross-section of t... Read More about Unique topological characterization of braided magnetic fields.