R. Gafeira
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View article: Magnetic braking and dynamo evolution of <i>β</i> Hydri
Magnetic braking and dynamo evolution of <i>β</i> Hydri Open
The evolution of magnetic braking and dynamo processes in subgiant stars is essential for understanding how these stars lose angular momentum. In this work, we investigate the magnetic braking and dynamo evolution of the G-type subgiant β …
View article: Diagnosing the solar atmosphere through the Mg I b<sub>2</sub> 5173 Å line
Diagnosing the solar atmosphere through the Mg I b<sub>2</sub> 5173 Å line Open
Context. The Mg I b 2 line at 5173 Å is primarily magnetically sensitive to heights between the mid photosphere and the low chromosphere, a region that has not been sufficiently explored in the solar atmosphere but is crucial for understan…
View article: Long-term properties of coronal off-limb structures
Long-term properties of coronal off-limb structures Open
Context. Extracting plasma structures in the solar corona (e.g. jets, loops, prominences) from spacecraft imagery data is essential in order to ascertain their unique properties and for our understanding of their evolution. Aims. Hence, ou…
View article: The Sun at millimeter wavelengths
The Sun at millimeter wavelengths Open
Magnetohydrodynamic (MHD) waves, playing a crucial role in transporting energy through the solar atmosphere, manifest in various chromospheric structures. Here, we investigated MHD waves in a long-lasting dark fibril using high-temporal-re…
View article: The Sun at millimeter wavelengths V. Magnetohydrodynamic waves in a fibrillar structure
The Sun at millimeter wavelengths V. Magnetohydrodynamic waves in a fibrillar structure Open
Magnetohydrodynamic (MHD) waves, playing a crucial role in transporting energy through the solar atmosphere, manifest in various chromospheric structures. Here, we investigated MHD waves in a long-lasting dark fibril using high-temporal-re…
View article: Sausage, kink, and fluting magnetohydrodynamic wave modes identified in solar magnetic pores by Solar Orbiter/PHI
Sausage, kink, and fluting magnetohydrodynamic wave modes identified in solar magnetic pores by Solar Orbiter/PHI Open
Solar pores are intense concentrations of magnetic flux that emerge through the solar photosphere. When compared to sunspots, they are much smaller in diameter and can therefore be affected and buffeted by neighbouring granular activity to…
View article: Identifying and Tracking Solar Flux Ropes in Simulation Data and Deflection Analysis of AR11176 and AR12473 Flux Ropes
Identifying and Tracking Solar Flux Ropes in Simulation Data and Deflection Analysis of AR11176 and AR12473 Flux Ropes Open
To improve our understanding of how space weather affects our near-Earth space environment, magnetic field modelling of solar eruptive structures is essential. In particular, modelling flux ropes in a time-dependent manner to investigate t…
View article: Sunspots Identification Through Mathematical Morphology
Sunspots Identification Through Mathematical Morphology Open
The implementation of automated methods for sunspot detection is essential to obtain better objectivity, efficiency, and accuracy in identifying sunspots and analysing their morphological properties. A desired application is the contouring…
View article: The automatic identification and tracking of coronal flux ropes
The automatic identification and tracking of coronal flux ropes Open
Context. Constructing the relevant magnetic field lines from active region modelling data is crucial to understanding the underlying instability mechanisms that trigger the corresponding eruptions. Aims. We present a magnetic flux rope (FR…
View article: The Automatic Identification and Tracking of Coronal Flux Ropes -- Part II: New Mathematical Morphology-based Flux Rope Extraction Method and Deflection Analysis
The Automatic Identification and Tracking of Coronal Flux Ropes -- Part II: New Mathematical Morphology-based Flux Rope Extraction Method and Deflection Analysis Open
We present a magnetic flux rope (FR) extraction tool for solar coronal magnetic field modelling data, which builds upon the methodology from Wagner et al. (2023). We apply the scheme to magnetic field simulations of active regions AR12473 …
View article: Analysis of full-disc H<i>α</i>observations: Carrington maps and filament properties in 1909–2022
Analysis of full-disc H<i>α</i>observations: Carrington maps and filament properties in 1909–2022 Open
Context. Full-disc observations of the Sun in the H α line provide information about the solar chromosphere, and in particular, about the filaments, which are dark and elongated features that lie along magnetic field polarity-inversion lin…
View article: Analysis of full-disc H alpha observations: Carrington maps and filament properties in 1909-2022
Analysis of full-disc H alpha observations: Carrington maps and filament properties in 1909-2022 Open
Full disc observations of the Sun in the H$α$ line provide information about the solar chromosphere and in particular about the filaments, which are dark and elongated features that lie along magnetic field polarity inversion lines. This m…
View article: Machine learning in solar physics
Machine learning in solar physics Open
The application of machine learning in solar physics has the potential to greatly enhance our understanding of the complex processes that take place in the atmosphere of the Sun. By using techniques such as deep learning, we are now in the…
View article: Machine learning in solar physics
Machine learning in solar physics Open
The application of machine learning in solar physics has the potential to greatly enhance our understanding of the complex processes that take place in the atmosphere of the Sun. By using techniques such as deep learning, we are now in the…
View article: Total Electron Content PCA-NN Prediction Model for South-European Middle Latitudes
Total Electron Content PCA-NN Prediction Model for South-European Middle Latitudes Open
A regression-based model was previously developed to forecast total electron content (TEC) at middle latitudes. We present a more sophisticated model using neural networks (NN) instead of linear regression. This regional model prototype si…
View article: A study of the capabilities for inferring atmospheric information from high-spatial-resolution simulations
A study of the capabilities for inferring atmospheric information from high-spatial-resolution simulations Open
In this work, we study the accuracy that can be achieved when inferring the atmospheric information from realistic numerical magneto-hydrodynamic simulations that reproduce the spatial resolution we will obtain with future observations mad…
View article: A study of the capabilities for inferring atmospheric information from high-spatial-resolution simulations
A study of the capabilities for inferring atmospheric information from high-spatial-resolution simulations Open
In this work, we study the accuracy that can be achieved when inferring the atmospheric information from realistic numerical magneto-hydrodynamic simulations that reproduce the spatial resolution we will obtain with future observations mad…
View article: Total electron content PCA-NN model for middle latitudes
Total electron content PCA-NN model for middle latitudes Open
A regression-based model was previously developed to forecast the total electron content (TEC) at middle latitudes. We present a more sophisticated model using neural networks (NN) instead of linear regression. This regional model prototyp…
View article: Satellite Star Tracker Breadboard with Space Debris Detection Capability for LEO
Satellite Star Tracker Breadboard with Space Debris Detection Capability for LEO Open
This paper evaluates the possibility of having a star tracker device running space debris algorithms. A simple star tracker breadboard was developed to evaluate the possibility of having a device running both stellar identification and spa…
View article: Payload Camera Breadboard for Space Surveillance—Part I: Breadboard Design and Implementation
Payload Camera Breadboard for Space Surveillance—Part I: Breadboard Design and Implementation Open
The rapid increase of space debris poses a risk to space activities, so it is vital to develop countermeasures in terms of space surveillance to prevent possible threats. The current Space Surveillance Network is majorly composed of radar …
View article: Different types of PCA-NN model for TEC with space weather parameters as predictors: advantages and disadvantages of different NN algorithms
Different types of PCA-NN model for TEC with space weather parameters as predictors: advantages and disadvantages of different NN algorithms Open
A PCA-NN model for the total electron content (TEC) for the midlatitudinal region (Iberian Peninsula) presented here uses the principal component analysis (PCA) to decompose TEC variations into different modes and to reconstruct/forecast a…
View article: Exploring Magnetic Loops and Serpentine Fields in the Quiet Sun with the GRIS-IFU
Exploring Magnetic Loops and Serpentine Fields in the Quiet Sun with the GRIS-IFU Open
Synthetic observations produced from radiative magnetohydrodynamic simulations have predicted that higher polarization fractions in the quiet solar photosphere would be revealed by increasing the total integration time of observations at G…
View article: Solar and Stellar Coronal Mass Ejections - a review of the Cool Stars 21 splinter session
Solar and Stellar Coronal Mass Ejections - a review of the Cool Stars 21 splinter session Open
Coronal mass ejections (CMEs) are the most energetic phenomena related to magnetic activity and, by impacting the interplanetary space, they can be the source of severe planetary disturbances. Solar CMEs and their sources, such as flares …
View article: Exploring magnetic loops and serpentine fields in the quiet Sun with the GRIS-IFU
Exploring magnetic loops and serpentine fields in the quiet Sun with the GRIS-IFU Open
Synthetic observations produced from radiative magnetohydronamic simulations have predicted that higher polarization fractions in the quiet solar photosphere would be revealed by increasing the total integration time of observations at GRE…
View article: The European Solar Telescope
The European Solar Telescope Open
The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the Europ…
View article: DeSIRe: Departure coefficient aided Stokes Inversion based on Response functions
DeSIRe: Departure coefficient aided Stokes Inversion based on Response functions Open
Future ground-based telescopes, such as the 4-metre class facilities DKIST and EST, will dramatically improve on current capabilities for simultaneous multi-line polarimetric observations in a wide range of wavelength bands, from the near-…
View article: DeSIRe: Departure coefficient aided Stokes Inversion based on Response functions
DeSIRe: Departure coefficient aided Stokes Inversion based on Response functions Open
Future ground-based telescopes, such as the 4-metre class facilities DKIST and EST, will dramatically improve on current capabilities for simultaneous multi-line polarimetric observations in a wide range of wavelength bands, from the near-…
View article: Testing the Accuracy of Coimbra Astronomical Observatory Solar Filament Historical Series (1929–1941)
Testing the Accuracy of Coimbra Astronomical Observatory Solar Filament Historical Series (1929–1941) Open
View article: Diagnostic capabilities of spectropolarimetric observations for understanding solar phenomena
Diagnostic capabilities of spectropolarimetric observations for understanding solar phenomena Open
Future ground-based telescopes will expand our capabilities for simultaneous multi-line polarimetric observations in a wide range of wavelengths, from the near-ultraviolet to the near-infrared. This creates a strong demand to compare candi…
View article: Diagnostic capabilities of spectropolarimetric observations for understanding solar phenomena I. Zeeman-sensitive photospheric lines
Diagnostic capabilities of spectropolarimetric observations for understanding solar phenomena I. Zeeman-sensitive photospheric lines Open
Future ground-based telescopes will expand our capabilities for simultaneous multi-line polarimetric observations in a wide range of wavelengths, from the near-ultraviolet to the near-infrared. This creates a strong demand to compare candi…