939 resultados para Sun: photosphere


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This paper aims to study and highlight the profile of the high speed rail (HSR) passenger in the case of the well-known sun and beach destination of Alicante, located in the Southeast of Spain. This region, which is directly connected with Madrid, differs from others because of its warm and sunny weather. The province is a tourist destination for both Spanish citizens and foreigners. However, the studies on the dynamics of the corridor towards Madrid and Alicante regarding HSR are quite recent and it is not possible to draw final conclusions about its impact on tourist mobility.

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A beautiful sweeping story of two sisters caught up in the events of the Nigerian civil war, ending in chilling violence which shocked the entire world.

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Eleven-page notebook containing John Winthrop's handwritten observations and calculations. Titled by Winthrop "Observations of 'Spots' on ye Sun with ye Naked Eye," this is the first known record of his scientific observations and records what he saw while examining the sun "with an 8 foot telescope from 6 a.m. til sun set" on the Boston Commons and concluding with "a considerable aurora borealis" that night (April 20, 1739). It has been speculated that his reference to the aurora borealis in these observations may indicate that he recognized the interrelation of the aurora borealis and sun spots, a concept which was not definitively established until the mid-nineteenth century.

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Solar nebula processes led to a depletion of volatile elements in different chondrite groups when compared to the bulk chemical composition of the solar system deduced from the Sun's photosphere. For moderately-volatile elements, this depletion primarily correlates with the element condensation temperature and is possibly caused by incomplete condensation from a hot solar nebula, evaporative loss from the precursor dust, and/or inherited from the interstellar medium. Element concentrations and interelement ratios of volatile elements do not provide a clear picture about responsible mechanisms. Here, the abundance and stable isotope composition of the moderately- to highly-volatile element Se are investigated in carbonaceous, ordinary, and enstatite chondrites to constrain the mechanism responsible for the depletion of volatile elements in planetary bodies of the inner solar system and to define a δ(82/78)Se value for the bulk solar system. The δ(82/78)Se of the studied chondrite falls are identical within their measurement uncertainties with a mean of −0.20±0.26‰ (2 s.d., n=14n=14, relative to NIST SRM 3149) despite Se abundance depletions of up to a factor of 2.5 with respect to the CI group. The absence of resolvable Se isotope fractionation rules out a kinetic Rayleigh-type incomplete condensation of Se from the hot solar nebula or partial kinetic evaporative loss on the precursor material and/or the parent bodies. The Se depletion, if acquired during partial condensation or evaporative loss, therefore must have occurred under near equilibrium conditions to prevent measurable isotope fractionation. Alternatively, the depletion and cooling of the nebula could have occurred simultaneously due to the continuous removal of gas and fine particles by the solar wind accompanied by the quantitative condensation of elements from the pre-depleted gas. In this scenario the condensation of elements does not require equilibrium conditions to avoid isotope fractionation. The results further suggest that the processes causing the high variability of Se concentrations and depletions in ordinary and enstatite chondrites did not involve any measurable isotope fractionation. Different degrees of element depletions and isotope fractionations of the moderately-volatile elements Zn, S, and Se in ordinary and enstatite chondrites indicate that their volatility is controlled by the thermal stabilities of their host phases and not by the condensation temperature under canonical nebular conditions.

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The first edition has title: Azimuth tables ... By Lieutenant S. Schroeder ... and Master W. H. H. Southerland ... Washington, Govt. print. off., 1882.

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Mode of access: Internet.

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Mode of access: Internet.

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Illustrated t.-p.

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Publication 3062.