High Resolution Optical Spectroscopy of the F Supergiant Proto-Planetary Nebula V887 Her=IRAS 18095+2704

An abundance analysis is presented for IRAS 18095+2704 (V887 Her), a post-AGB star and proto-planetary nebula. The analysis is based on high-resolution optical spectra from the McDonald Observatory and the Special Astrophysical Observatory. Standard analysis using a classical Kurucz model atmosphere and the line analysis program MOOG provides the atmospheric parameters: Teff = 6500 K, log g = +0.5, and a microturbulent velocity Vt = 4.7 km/s and [Fe/H] = -0.9. Extraction of these parameters is based on excitation of FeI lines, ionization equilibrium between neutral and ions of Mg, Ca, Ti, Cr, and Fe, and the wings of hydrogen Paschen lines. Elemental abundances are obtained for 22 elements and upper limits for an additional four elements. These results show that the star's atmosphere has not experienced a significant number of C- and s-process enriching thermal pulses. Abundance anomalies as judged relative to the compositions of unevolved and less-evolved normal stars of a similar metallicity include Al, Y, and Zr deficiencies with respect to Fe of about 0.5 dex. Judged by composition, the star resembles a RV Tauri variable that has been mildly affected by dust-gas separation reducing the abundances of the elements of highest condensation temperature. This separation may occur in the stellar wind. There are indications that the standard 1D LTE analysis is not entirely appropriate for IRAS 18095+2704. These include a supersonic macroturbulent velocity of 23 km/s, emission in H-alpha and the failure of predicted profiles to fit observed profiles of H-beta and H-gamma.Comment: Accepted for publication in MNRA

An upper limit on the sulphur abundance in HE 1327-2326

Context: Star HE 1327-2326 is a unique object, with the lowest measured iron abundance ([Fe/H] ~ -6) and a peculiar chemical composition that includes large overabundances of C, N, and O with respect to iron. One important question is whether the chemical abundances in this star reflect the chemical composition of the gas cloud from which it was formed or if they have been severely affected by other processes, such as dust-gas winnowing. Aims: We measure or provide an upper limit to the abundance of the volatile element sulphur, which can help to discriminate between the two scenarios. Methods: We observed HE 1327-2326 with the high resolution infra-red spectrograph CRIRES at the VLT to observe the S I lines of Multiplet 3 at 1045 nm. Results: We do not detect the S I line. A 3sigma$upper limit on the equivalent width (EW) of any line in our spectrum is EW<0.66 pm. Using either one-dimensional static or three-dimensional hydrodynamical model-atmospheres, this translates into a robust upper limit of [S/H]<-2.6. Conclusions: This upper limit does not provide conclusive evidence for or against dust-gas winnowing, and the evidence coming from other elements (e.g., Na and Ti) is also inconclusive or contradictory. The formation of dust in the atmosphere versus an origin of the metals in a metal-poor supernova with extensive "fall-back" are not mutually exclusive. It is possible that dust formation distorts the peculiar abundance pattern created by a supernova with fall-back, thus the abundance ratios in HE 1327-2326 may be used to constrain the properties of the supernova(e) that produced its metals, but with some caution.Comment: Accepted by Astronomy & Astrophysics Minor typos in the abstract correcte

Spitzer reveals what's behind Orion's Bar

We present Spitzer Space Telescope observations of 11 regions SE of the Bright Bar in the Orion Nebula, along a radial from the exciting star theta1OriC, extending from 2.6 to 12.1'. Our Cycle 5 programme obtained deep spectra with matching IRS short-high (SH) and long-high (LH) aperture grid patterns. Most previous IR missions observed only the inner few arcmin. Orion is the benchmark for studies of the ISM particularly for elemental abundances. Spitzer observations provide a unique perspective on the Ne and S abundances by virtue of observing the dominant ionization states of Ne (Ne+, Ne++) and S (S++, S3+) in Orion and H II regions in general. The Ne/H abundance ratio is especially well determined, with a value of (1.01+/-0.08)E-4. We obtained corresponding new ground-based spectra at CTIO. These optical data are used to estimate the electron temperature, electron density, optical extinction, and the S+/S++ ratio at each of our Spitzer positions. That permits an adjustment for the total gas-phase S abundance because no S+ line is observed by Spitzer. The gas-phase S/H abundance ratio is (7.68+/-0.30)E-6. The Ne/S abundance ratio may be determined even when the weaker hydrogen line, H(7-6) here, is not measured. The mean value, adjusted for the optical S+/S++ ratio, is Ne/S = 13.0+/-0.6. We derive the electron density versus distance from theta1OriC for [S III] and [S II]. Both distributions are for the most part decreasing with increasing distance. A dramatic find is the presence of high-ionization Ne++ all the way to the outer optical boundary ~12' from theta1OriC. This IR result is robust, whereas the optical evidence from observations of high-ionization species (e.g. O++) at the outer optical boundary suffers uncertainty because of scattering of emission from the much brighter inner Huygens Region.Comment: 60 pages, 16 figures, 10 tables. MNRAS accepte

First observation of Jupiter by XMM-Newton

We present the first X-ray observation of Jupiter by XMM-Newton. Images taken with the EPIC cameras show prominent emission, essentially all confined to the 0.2-2.0 keV band, from the planet's auroral spots; their spectra can be modelled with a combination of unresolved emission lines of highly ionised oxygen (OVII and OVIII), and a pseudo-continuum which may also be due to the superposition of many weak lines. A 2.8 sigma enhancement in the RGS spectrum at 21-22 A (~0.57 keV) is consistent with an OVII identification. Our spectral analysis supports the hypothesis that Jupiter's auroral emissions originate from the capture and acceleration of solar wind ions in the planet's magnetosphere, followed by X-ray production by charge exchange. The X-ray flux of the North spot is modulated at Jupiter's rotation period. We do not detect evidence for the ~45 min X-ray oscillations observed by Chandra more than two years earlier. Emission from the equatorial regions of the planet's disk is also observed. Its spectrum is consistent with that of scattered solar X-rays.Comment: 7 pages, 9 figures; to be published in Astronomy & Astrophysic

Changes in the foreign trade of the Russian Federation after the introduction of sanctions

Tato diplomová práce je zaměřena na změny zahraničního obchodu Ruska po zavedení mezinárodních ekonomických sankcí v roce 2014. První kapitola je věnována teoretickému aspektu sankcí. Probírají se druhy sankcí, jejích legitimita, stejně jako rozdíl sankcí a obchodních válek. Druhá kapitola je zaměřena na zahraniční obchod Ruska, a konkrétně na obchodní politiku státu, stejně jako změnu teritoriální a komoditní struktury obchodu. Ve třetí kapitole se zkoumají hlavní změny obchodní politiky Ruska po uvalení sankcí, kterými jsou substituce dovozu a obrat Ruska k Asii.This diploma thesis deals with changes in Russia's foreign trade after the introduction of international economic sanctions in 2014. The first chapter describes theoretical aspects of sanctions. The types of sanctions, their legitimacy, as well as the difference between sanctions and trade wars are discussed. The second chapter focuses on Russia's foreign trade, and specifically on the state's trade policy, as well as the changes in the territorial and commodity structure of foreign trade. The third chapter examines the main changes in Russia's trade policy since the imposition of sanctions, which are import substitution and Russia's pivot to Asia

Business and economic relations between Russia and France

Bakalářská práce je věnována obchodním a ekonomickým vztahům Ruska a Francie. Práce je rozdělena do tří kapitol. První kapitola se věnuje analýze obyvatelstva a rozlohy států, stejně jako strukturám jejích ekonomik. Ve druhé kapitole jsou analyzovány obchodní a ekonomické vztahy mezi zeměmi. Třetí kapitola je věnována společnostem Renault a Total, které jsou významnými francouzskými podniky, působícími na ruském trhu. Hlavním cílem práce je určit intenzitu obchodních vztahů Ruska a Francie a odpovědět na otázku, zda jsou francouzské podniky přítomné na ruském trhu.The bachelor thesis is dedicated to business and economic relations between Russia and France. The thesis is divided into three chapters. The first chapter is focused on the analysis of the state’s population, the size of their territories, as well as the structure of their economies. Business and economic relations between countries are analysed in the second chapter of the thesis. The third chapter is dedicated to Renault and Total, which are major French companies operating in Russia. The main target of the thesis is to determine the intensity of business relations between Russia and France and to answer the question whether French companies are present on the Russian market