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In the following short review we will outline some of the possible interaction processes of lower solar atmospheric plasma with the embedded small-scale solar magnetic fields. After introducing the topic, important types of small-scale solar magnetic field elements are outlined to then focus on their creation and evolution, and finally end up describing foremost processes these magnetic fields are involved in, such as the reconnection of magnetic field lines and the creation of magneto-hydrodynamic waves. The occurrence and global coverage in the solar atmosphere of such small-scale phenomena surpass on average those of the more explosive and intense events, mainly related to solar active regions, and therefore their key role as building blocks of solar activity even during the weaker phases of the 11-year solar cycle. In particular, understanding the finest ingredients of solar activity from the lower to the upper solar atmosphere could be determinant to fully understand the heating of the solar corona, which stands out as one of the most intriguing problems in astrophysics nowadays., Comment: 44 pages, 11 figures, Accepted for publication in Reviews of Modern Plasma Physics

Energy dissipation in collisionless plasmas is a longstanding fundamental physics problem. Although it is well known that magnetic reconnection and turbulence are coupled and transport energy from system-size scales to sub-proton scales, the details of the energy distribution and energy dissipation channels remain poorly understood. Especially, the energy transfer and transport associated with three dimensional (3D) small-scale reconnection that occurs as a consequence of a turbulent cascade is unknown. We use an explicit fully kinetic particle-in-cell code to simulate 3D small scale magnetic reconnection events forming in anisotropic and Alfv\'enic decaying turbulence. We identify a highly dynamic and asymmetric reconnection event that involves two reconnecting flux ropes. We use a two-fluid approach based on the Boltzmann equation to study the spatial energy transfer associated with the reconnection event and compare the power density terms in the two-fluid energy equations with standard energy-based damping, heating and dissipation proxies. Our findings suggest that the electron bulk flow transports thermal energy density more efficiently than kinetic energy density. Moreover, in our turbulent reconnection event, the energy-density transfer is dominated by plasma compression. This is consistent with turbulent current sheets and turbulent reconnection events, but not with laminar reconnection., Comment: Accepted for publication in Apj

Astronomical interest within the current Colombian territory has its roots in the Botanical Expedition of the New Kingdom of Granada (1783-1813), which stimulated the creation of an astronomical observatory in 1803, the first one established in the New World to pursue systematic observations and meteorological studies. After the death in 1816 of its first director, Francisco Jose de Caldas (1768-1816), during the convulsive independence period, no major astronomical observations were made for decades, with few exceptions. In this work we delve into the contributions of the astronomer Jose Maria Gonzalez Benito (1843-1903), main reactivator of the Observatorio Astron\'omico Nacional de Colombia in the second half of the 19th century, pointing out his pioneering efforts that put worldwide attention to it, and to his own private observatory making him one of the most committed figures to the development of astronomical sciences in the country and the most renowned Colombian in the international astronomical research scene of his time., Comment: 42 pages, 7 figures, 2 tables. Supplementary Material (10 figures, 2 tables). Accepted for publication in Revista de la Academia Colombiana de Ciencias Exactas, Fisicas y Naturales

We use 3D fully kinetic particle-in-cell simulations to study the occurrence of magnetic reconnection in a simulation of decaying turbulence created by anisotropic counter-propagating low-frequency Alfv\'en waves consistent with critical-balance theory. We observe the formation of small-scale current-density structures such as current filaments and current sheets as well as the formation of magnetic flux ropes as part of the turbulent cascade. The large magnetic structures present in the simulation domain retain the initial anisotropy while the small-scale structures produced by the turbulent cascade are less anisotropic. To quantify the occurrence of reconnection in our simulation domain, we develop a new set of indicators based on intensity thresholds to identify reconnection events in which both ions and electrons are heated and accelerated in 3D particle-in-cell simulations. According to the application of these indicators, we identify the occurrence of reconnection events in the simulation domain and analyse one of these events in detail. The event is related to the reconnection of two flux ropes, and the associated ion and electron exhausts exhibit a complex three-dimensional structure. We study the profiles of plasma and magnetic-field fluctuations recorded along artificial-spacecraft trajectories passing near and through the reconnection region. Our results suggest the presence of particle heating and acceleration related to small-scale reconnection events within magnetic flux ropes produced by the anisotropic Alfv\'enic turbulent cascade in the solar wind. These events are related to current structures of order a few ion inertial lengths in size., Comment: Accepted for publication in J. Plasma Phys

The aim of this paper is to encourage science educators and outreach groups to look appropriately at the Sun and consider it as an extraordinary pedagogical tool to teach science at all education stages, what we call here as the solar educational spectrum, i.e., from K-12 to higher education, to develop informal educational projects that may lead to reach more complex material and to enlarge the experience at each stage. We review the main aspects of the Sun as an appetizer of the endless source of ideas to perform informal educational projects outside of a structured curriculum. We end up our discussion by sharing our experience across the educational spectrum in Colombia and how we used it as a development instrument., Comment: 13 pages, 5 figures, comments Welcome. V2. Minor changes

In this work we describe the implementation and analysis of different optimization algorithms used for finding the best set of parameters for a Fuzzy Inference System intended to classify solar flares. The parameters will be identified among a universe of possible solutions for the algorithms, and the system will be tested in the particular case of dealing with the aim of classifying the solar flares., Comment: 14 pages, 2 figures, 18 tables. Accepted for publication in TECCIENCIA

On Thursday, September 1, 1859, the British astronomer Richard Carrington, for the first time ever, observes a spectacular gleam of visible light on the surface of the solar disk, the photosphere. The Carrington Event, as it is nowadays known by scientists, occurred because of the high solar activity that had visible consequences on Earth, in particular reports of outstanding aurorae activity that amazed thousands of people in the western hemisphere during the dawn of September 2. The geomagnetic storm, generated by the solar-terrestrial event, had such a magnitude that the auroral oval expanded towards the equator, allowing low latitudes, like Panama's 9$^\circ$ N, to catch a sight of the aurorae. An expedition was carried out to review several historical reports and books from the northern cities of Colombia, allowing the identification of a narrative from Monter\'ia, Colombia (8$^\circ$ 45' N), that describes phenomena resembling those of an aurorae borealis, such as fire-like lights, blazing and dazzling glares, and the appearance of an immense S-like shape in the sky. The very low latitude of the geomagnetic north pole in 1859, the lowest value in over half a millennia, is proposed to have allowed the observations of auroral events at locations closer to the equator, and supports the historical description found in Colombia. The finding of such chronicle represents one of the most complete descriptions of low-latitude sightings of aurorae caused by the Carrington Event., Comment: 26 pages, 10 figures. Accepted for publication in Advances in Space Research

Dynamics of hot chromospheric plasma of solar flares is a key to understanding of mechanisms of flare energy release and particle acceleration. A moderate M1.0 class flare of 12 June, 2014 (SOL2014-06-12T21:12) was simultaneously observed by NASA's Interface Region Imaging Spectrograph (IRIS), other spacecraft, and also by New Solar Telescope (NST) at the BBSO. This paper presents the first part of our investigation focused on analysis of the IRIS data. Our analysis of the IRIS data in different spectral lines reveals strong redshifted jet-like flow with the speed of ~100 km/s of the chromospheric material before the flare. Strong nonthermal emission of the C II k 1334.5 A line, formed in the chromosphere-corona transition region, is observed at the beginning of the impulsive phase in several small (with a size of ~1 arcsec) points. It is also found that the C II k line is redshifted across the flaring region before, during and after the impulsive phase. A peak of integrated emission of the hot (1.1 MK) plasma in the Fe XXI 1354.1 A line is detected approximately 5 minutes after the integrated emission peak of the lower temperature C II k. A strong blueshift of the Fe XXI line across the flaring region corresponds to evaporation flows of the hot chromospheric plasma with a speed of 50 km/s. Additional analysis of the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) data supports the idea that the upper chromospheric dynamics observed by IRIS has features of "gentle" evaporation driven by heating of the solar chromosphere by accelerated electrons and by a heat flux from the flare energy release site., Comment: 44 pages, 15 figures

State-of-the-art solar instrumentation is revealing magnetic activity of the Sun with unprecedented resolution. Observations with the 1.6m New Solar Telescope of the Big Bear Solar Observatory are making next steps in our understanding of the solar surface structure. Granular-scale magnetic flux emergence and the response of the solar atmosphere are among the key research. As part of a joint observing program with NASA's IRIS mission, the NST observed active region NOAA 11810 in photospheric and chromospheric wavelengths. Complimentary data are provided by SDO and Hinode space-based telescopes. The region displayed a group of solar pores, in the vicinity of which we detect a small-scale buoyant horizontal magnetic flux tube causing abnormal granulation and interacting with the pre-existing ambient field in upper atmospheric layers. Following the expansion of distorted granules at the emergence site, we observed a sudden appearance of an extended surge in the HeI data. IRIS catched ejection of a hot plasma jet associated with the HeI-surge. The SDO/HMI data reveal emerging magnetic looplike structures. Hinode/Ca II H and IRIS filtergrams detail the connectivities of the newly emerged magnetic field in the lower solar chromosphere. From these data we fid that the orientation of the emerging flux tube was almost perpendicular to the overlying ambient field. Nevertheless the interaction of emerging magnetic field lines with the pre-existing overlying field generates high-temperature emission regions and boosts the surge/jet production. The localized heating is detected before and after the first signs of the surge/jet ejection. We compare the results with previous observations and theoretical models, and propose a scenario for the activation of plasma jet/surges and confined heating. Such process may play a significant role in the mass and energy flow from the interior to the corona., Comment: 6 figures

Understanding the solar outer atmosphere requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1" and 0.3"), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 17 and 127 nm. The LEMUR slit covers 280" on the Sun with 0.14" per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km/s or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission., Comment: 35 pages, 14 figures. To appear on Experimental Astronomy

Recent studies of NOAA active region 10953, by Okamoto {\it et al.} ({\it Astrophys. J. Lett.} {\bf 673}, 215, 2008; {\it Astrophys. J.} {\bf 697}, 913, 2009), have interpreted photospheric observations of changing widths of the polarities and reversal of the horizontal magnetic field component as signatures of the emergence of a twisted flux tube within the active region and along its internal polarity inversion line (PIL). A filament is observed along the PIL and the active region is assumed to have an arcade structure. To investigate this scenario, MacTaggart and Hood ({\it Astrophys. J. Lett.} {\bf 716}, 219, 2010) constructed a dynamic flux emergence model of a twisted cylinder emerging into an overlying arcade. The photospheric signatures observed by Okamoto {\it et al.} (2008, 2009) are present in the model although their underlying physical mechanisms differ. The model also produces two additional signatures that can be verified by the observations. The first is an increase in the unsigned magnetic flux in the photosphere at either side of the PIL. The second is the behaviour of characteristic photospheric flow profiles associated with twisted flux tube emergence. We look for these two signatures in AR 10953 and find negative results for the emergence of a twisted flux tube along the PIL. Instead, we interpret the photospheric behaviour along the PIL to be indicative of photospheric magnetic cancellation driven by flows from the dominant sunspot. Although we argue against flux emergence within this particular region, the work demonstrates the important relationship between theory and observations for the successful discovery and interpretation of signatures of flux emergence., Comment: 14 pages, 8 figures, accepted for publication in Solar Physics