3D seismic evidence of internal structure within Tampen Slide deposits on the North Sea Fan : are chaotic deposits that chaotic?

The seismic character of slide deposits is typically described as structureless or chaotic. However, 3D seismic data from the northern flank of the North Sea Fan reveal recognizable internal, penetrative structures within the Tampen Slide deposits. The study of its seismic attributes allowed an integrated characterization of the slide deposits and has shown distinctive acoustic fabrics, both at the top and base of the slide deposit, which are interpreted to be the expression of internal deformation structures. Based on their geometry, four main seismic fabric types have been defined: anastomosing, curvilinear, rectilinear and wispy. The spatial distribution of the fabric was mainly controlled by a topographic high present on the sea-bed at the time of the gravitational collapse, which influenced the transport of material. Areas of distinct fabrics are thought to reflect different flow behaviour during the latest stages of the mass movement and could be considered kinematic indicators. The results give new insights into the transport and deformation processes of submarine mass movements and highlight the potential of detailed analysis of 3D seismic data

Morphological properties of slender Ca II H fibrils observed by Sunrise II

R. Gafeira et. al.©2017 The American Astronomical Society. All rights reserved. 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 we use intensity images taken with the SuFI instrument in the Ca ii H line during the second scientific flight of the Sunrise observatory to identify and track elongated bright structures. After identification, we analyze theses structures to extract their morphological properties. We identify 598 slender Ca ii H fibrils (SCFs) with an average width of around 180 km, length between 500 and 4000 km, average lifetime of ≈400 s, and average curvature of 0.002 arcsec−1. The maximum lifetime of the SCFs within our time series of 57 minutes is ≈2000 s. We discuss similarities and differences of the SCFs with other small-scale, chromospheric structures such as spicules of type I and II, or Ca ii K fibrils.The German contribution to Sunrise and its reflight was funded by the Max Planck Foundation, the Strategic Innovations Fund of the President of the Max Planck Society (MPG), the Deutsche Zentrum für Luft- und Raumfahrt (DLR), and private donations by supporting members of the Max Planck Society, which is gratefully acknowledged. The Spanish contribution was funded by the Ministerio de Economía y Competitividad under Projects ESP2013-47349-C6 and ESP2014-56169-C6, partially using European FEDER funds. The HAO contribution was partly funded through NASA grant number NNX13AE95G. This work was partly supported by the BK21 plus program through the National Research Foundation (NRF) funded by the Ministry of Education of Korea. S.J. receives support from the Research Council of Norway.Peer reviewe

Temporal evolution of short-lived penumbral microjets

Context. Penumbral microjets are elongated jet-like brightenings observed in the chromosphere above sunspot penumbrae. They are transient events that last from a few seconds to several minutes and are thought to originate from magnetic reconnection processes. Previous studies have mainly focused on their morphological and spectral characteristics, and more recently on their spectropolarimetric signals during the maximum brightness stage. Studies addressing the temporal evolution of PMJs have also been carried out, but they are based on spatial and spectral time variations only. Aims. Here we investigate the temporal evolution of the polarization signals produced by short-lived PMJs (lifetimes $<$ 2 minutes) to infer how the magnetic field vector evolves in the upper photosphere and mid-chromosphere. Methods. We use fast-cadence spectropolarimetric observations of the Ca II 854.2 nm line taken with the CRisp Imaging Spectropolarimeter at the Swedish 1-m Solar Telescope. The weak-field approximation (WFA) is used to estimate the strength and inclination of the magnetic field vector. Results. The WFA reveals larger magnetic field changes in the upper photosphere than in the chromosphere during the PMJ maximum brightness stage. In the photosphere, the magnetic field inclination and strength undergo a transient increase for most PMJs, but in 25$\%$ of the cases the field strength decreases during the brightening. In the chromosphere, the magnetic field tends to be slightly stronger during the PMJs. Conclusions. The propagation of compressive perturbation fronts followed by a rarefaction phase in the aftershock region may explain the observed behavior of the magnetic field vector. The fact that such behavior varies among the analyzed PMJs could be a consequence of the limited temporal resolution of the observations and the fast-evolving nature of the PMJs.Comment: Paper accepted for publication in section 9. The Sun and the Heliosphere of Astronomy and Astrophysics. 18 pages, 21 figure

Satellite Star Tracker Breadboard with Space Debris Detection Capability for LEO

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 space debris algorithms. The breadboard was built with commercial off-the-shelf components, representing the current star tracker resolution and field of view. A star tracker device and space debris algorithms were implemented and tested, respectively: Tetra and ASTRiDE. The device concept was tested by taking pictures of the night sky with satellite streaks. Seeking to overcome such limitations, a dual-purpose star tracker with stars detection and optical debris detection capability is proposed. Star trackers are usually used in satellites for attitude determination and therefore have a vast potential to be a major tool for space debris detection. The rapid increase of space debris poses a risk to space activities, so it is vital to detect it. Ground-based radar and optical telescope techniques used for debris detection are limited by a size threshold, detecting only a tiny amount of the total, reason why evaluating the possibility of detecting them in space is of major importance.info:eu-repo/semantics/publishedVersio

Oscillations on width and intensity of slender Ca II H fibrils from Sunrise/SuFI

R. Gafeira et. al.©2017 The American Astronomical Society. All rights reserved. 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 obvious oscillations in their intensity, but also their width. The oscillatory behaviors are investigated at several positions along the axes of the SCFs. A large majority of fibrils show signs of oscillations in intensity. Their periods and phase speeds are analyzed using a wavelet analysis. The width and intensity perturbations have overlapping distributions of the wave period. The obtained distributions have median values of the period of 32 ± 17 s and 36 ± 25 s, respectively. We find that the fluctuations of both parameters propagate in the SCFs with speeds of ${11}_{-11}^{+49}$ km s−1 and ${15}_{-15}^{+34}$ km s−1, respectively. Furthermore, the width and intensity oscillations have a strong tendency to be either in anti-phase or, to a smaller extent, in phase. This suggests that the oscillations of both parameters are caused by the same wave mode and that the waves are likely propagating. Taking all the evidence together, the most likely wave mode to explain all measurements and criteria is the fast sausage mode.The German contribution to Sunrise and its reflight was funded by the Max Planck Foundation, the Strategic Innovations Fund of the President of the Max Planck Society (MPG), DLR, and private donations by supporting members of the Max Planck Society, which are gratefully acknowledged. The Spanish contribution was funded by the Ministerio de Economía y Competitividad under Projects ESP2013-47349-C6 and ESP2014-56169-C6, partially using European FEDER funds. The HAO contribution was partly funded through NASA grant No. NNX13AE95G. This work was partly supported by the BK21 plus program through the National Research Foundation (NRF) funded by the Ministry of Education of Korea. S.J. receives support from the Research Council of Norway.Peer reviewe

Machine learning in solar physics

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 position to analyze large amounts of data from solar observations and identify patterns and trends that may not have been apparent using traditional methods. This can help us improve our understanding of explosive events like solar flares, which can have a strong effect on the Earth environment. Predicting hazardous events on Earth becomes crucial for our technological society. Machine learning can also improve our understanding of the inner workings of the sun itself by allowing us to go deeper into the data and to propose more complex models to explain them. Additionally, the use of machine learning can help to automate the analysis of solar data, reducing the need for manual labor and increasing the efficiency of research in this field.Comment: 100 pages, 13 figures, 286 references, accepted for publication as a Living Review in Solar Physics (LRSP

Sunspots identification through mathematical morphology

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 of sunspots. In this work, we construct sunspot contours from Solar Dynamics Observatory (SDO)/ Helioseismic and Magnetic Imager intensity images by means of an automated method based on development and application of mathematical morphology. The method is validated qualitatively – the resulting contours accurately delimit sunspots. Here, it is applied to high-resolution data (SDO intensitygrams) and validated quantitatively by illustrating a good agreement between the measured sunspot areas and the ones provided by two standard reference catalogues. The method appears to be robust for sunspot identification, and our analysis suggests its application to more complex and irregular-shaped solar structures, such as polarity inversion lines inside delta-sunspots

A two-part seabed geomorphology classification scheme : (v.2). Part 1 : morphology features glossary

This report updates the ‘Two-part Seabed Geomorphology classification scheme’ of Dove et al. (2016) and presents a new glossary (Part 1) of Seabed Morphology features. This Morphology glossary is intended to provide marine scientists with a robust and consistent way to characterise the seabed. Each glossary entry includes a feature definition and a representative schematic diagram to support clear and accurate classification. Feature terms and definitions are primarily drawn from the International Hydrographic Organization (IHO) guide for undersea feature names, which are herein modified and augmented with additional terms to ensure the final feature catalogue and glossary encompasses the diversity of morphologies observed at the seabed, while also minimising duplication and/or ambiguity. This updated classification system and new glossary are the result of a collaboration between marine geoscientists from marine mapping programmes/networks in Norway (MAREANO), Ireland (INFOMAR), UK (MAREMAP), and Australia (Geoscience Australia) (MIM-GA). A subsequent report will present the (Part 2) Geomorphology feature glossar