Search results for " Solar"
showing 10 items of 958 documents
Nicolai Copernici ... De Reuolutionibus orbium coelestium Libri VI : Habes in hoc opere ... Motus stellarum, tam fixarum, quam erraticarum ... : Habe…
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Capll. orn.
Nanoflare Evidence from Analysis of the X-Ray Variability of an Active Region Observed with Hinode/XRT
2012
The heating of the solar corona is one of the big questions in astrophysics. Rapid pulses called nanoflares are among the best candidate mechanisms. The analysis of the time variability of coronal X-ray emission is potentially a very useful tool to detect impulsive events. We analyze the small-scale variability of a solar active region in a high cadence Hinode/XRT observation. The dataset allows us to detect very small deviations of emission fluctuations from the distribution expected for a constant rate. We discuss the deviations in the light of the pulsed-heating scenario.
Mean Interplanetary Magnetic Field Measurement Using the ARGO-YBJ Experiment
2011
The sun blocks cosmic ray particles from outside the solar system, forming a detectable shadow in the sky map of cosmic rays detected by the ARGO-YBJ experiment in Tibet. Because the cosmic ray particles are positive charged, the magnetic field between the sun and the earth deflects them from straight trajectories and results in a shift of the shadow from the true location of the sun. Here we show that the shift measures the intensity of the field which is transported by the solar wind from the sun to the earth.
Are high-temperature fractionations in the solar nebula preserved in highly siderophile element systematics of the Earth's mantle?
2004
The relative abundances of the highly siderophile elements (HSE) Os, Ir, Ru, Pt, Rh, and Pd in relatively pristine lherzolites differ from solar abundance ratios and are several orders of magnitude higher than predicted for equilibrium distribution between metal/silicate (core-mantle). The samples are characterized by a mean Ca/Al ratio of 1.18 ± 0.09 σM and a mean Ca/Si ratio of 0.10 ± 0.01 σM, overlapping with a mean Ca/Al of 1.069 ± 0.044 σM and a mean Ca/Si of 0.081 ± 0.023 σM found in chondrites (Wasson and Kallemeyn 1988). Interestingly, the CI-normalized abundance pattern shows decreasing solar system normalized abundances with increasing condensation temperatures. The abundance of …
Water and Geodynamics
2006
Hydrogen is the most abundant element (Fig. 1⇓) in the galaxy and our solar system (Lodders 2003). Therefore it is not astonishing that hydrogen is a key player in the geodynamic evolution of planets. Its fate in the early Earth, after condensation of the solar nebula, the accretion of our planet and hydrogen reprocessing through early asteroidal and cometary bombardment (Dauphas et al. 2000) and segregation of a proto-Earth into iron core and silicate mantle is described elsewhere in this volume (Marty and Yokochi 2006). Figure 1. Abundance of elements in the solar system in numbers of atoms per 106 atoms of silicon (Lodders 2003). This chapter concerns itself with the geodynamics of the m…
Small solar system bodies as granular systems
2017
Asteroids and other Small Solar System Bodies (SSSBs) are currently of great scientific and even industrial interest. Asteroids exist as the permanent record of the formation of the Solar System and therefore hold many clues to its understanding as a whole, as well as insights into the formation of planetary bodies. Additionally, SSSBs are being investigated in the context of impact risks for the Earth, space situational awareness and their possible industrial exploitation (asteroid mining). In all these aspects, the knowledge of the geophysical characteristics of SSSB surface and internal structure are of great importance. Given their size, constitution, and the evidence that many SSSBs ar…
The origin of slow electron recombination processes in dye-sensitized solar cells with alumina barrier coatings
2004
We investigate the effect of a thin alumina coating of nanocrystalline TiO2 films on recombination dynamics of dye-sensitized solar cells. Both coated and uncoated cells were measured by a combination of techniques: transient absorption spectroscopy, electrochemical impedance spectroscopy, and open-circuit voltage decay. It is found that the alumina barrier reduces the recombination of photoinjected electrons to both dye cations and the oxidized redox couple. It is proposed that this observed retardation can be attributed primarily to two effects: almost complete passivation of surface trap states in TiO2 that are able to inject electrons to acceptor species, and slowing down by a factor of…
Improving Perovskite Solar Cells: Insights From a Validated Device Model
2017
To improve the efficiency of existing perovskite solar cells (PSCs), a detailed understanding of the underlying device physics during their operation is essential. Here, a device model has been developed and validated that describes the operation of PSCs and quantitatively explains the role of contacts, the electron and hole transport layers, charge generation, drift and diffusion of charge carriers and recombination. The simulation to the experimental data of vacuum-deposited CH3NH3PbI3 solar cells over multiple thicknesses has been fit and the device behavior under different operating conditions has been studied to delineate the influence of the external bias, charge-carrier mobilities, e…
State selective electron injection in non-aggregated titanium phthalocyanine sensitised nanocrystalline TiO2 films
2004
We describe a novel titanium phthalocyanine that shows no aggregation when anchored to nanocrystalline TiO2 films through its axial carboxylated ligand without the use of co-adsorbents; state selective electron injection into the TiO2 is demonstrated, resulting in efficient photocurrent generation in dye sensitised photoelectrochemical solar cells. Palomares Gil, Emilio J, epagil@alumni.uv.es
A prospective new diagnostic technique for distinguishing eruptive and noneruptive active regions
2019
This research has received funding from the Science and Technology Facilities Council (UK) through the consolidated grant ST/N000609/1 and the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program (grant agreement No. 647214). This work used the DiRAC@Durham facility managed by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). The equipment was funded by BEIS capital funding via STFC capital grants ST/P002293/1, ST/R002371/1, and ST/S002502/1, Durham University and STFC operations grant ST/R000832/1. DiRAC is part of the National e-Infrastructure. S.L.Y. would like to acknowledge STFC for sup…