599 research outputs found

    The 2006 hot phase of Romano's star (GR 290) in M33

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    Understanding the nature of the instabilities of LBVs is important to understand the late evolutionary stages of very massive stars. We investigate the long term, S Dor-type variability of the luminous blue variable GR290 (Romano's star) in M33, and its 2006 minimum phase. New spectroscopic and photometric data taken in November and December 2006 were employed in conjunction with already published data on GR290 to derive the physical structure of GR290 in different phases and the time scale of the variability. We find that by the end of 2006, GR 290 had reached the deepest visual minimum so far recorded. Its present spectrum resembles closely that of the Of/WN9 stars, and is the hottest so far recorded in this star (and in any LBV as well), while its visual brightness decreased by about 1.4 mag. This first spectroscopic record of GR290 during a minimum phase confirms that, similarly to AG Car and other LBVs, the star is subject to ample S Dor-type variations, being hotter at minimum, suggesting that the variations take place at constant bolometric luminosity.Comment: 4 figures, 1 table, accepted for publication in A&A Letter

    The origin of the supersoft X-ray--optical/UV flux anticorrelation in the symbiotic binary AG Draconis

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    AG Draconis produces a strong supersoft X-ray emission.The X-ray and optical/UV fluxes are in a strict anticorrelation throughout the active and quiescent phases. The aim of this contribution is to identify the source of the X-ray emission and reveal the nature of the observed flux anticorrelation. For this purpose we model the X-ray and UV observations with XMM-Newton, far-UV spectroscopy from FUSE, low- and high-resolution IUE spectra and optical/near-IR spectroscopic and/or photometric observations. Our analysis showed that the supersoft X-ray emission is produced by the white dwarf photosphere. The X-ray and far-UV fluxes make it possible to determine its temperature unambiguously. The supersoft X-ray--optical/UV flux anticorrelation is caused by the variable wind from the hot star. The enhanced hot star wind gives rise to the optical bursts by reprocessing high-energy photons from the Lyman continuum to the optical/UV.Comment: 9 pages, 2 figures, 3 tables. Submitted to AA on 25/11/2008, revised on 27/05/200

    Hard X-ray emission from Eta Carinae

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    Context : If relativistic particle acceleration takes place in colliding-wind binaries, hard X-rays and gamma-rays are expected through inverse Compton emission, but to date these have never been unambiguously detected. Aims : To detect this emission, observations of Eta Carinae were performed with INTEGRAL, leveraging its high spatial resolution. Methods : Deep hard X-ray images of the region of Eta Car were constructed in several energy bands. Results : The hard X-ray emission previously detected by BeppoSax around Eta Car originates from at least 3 different point sources. The emission of Eta Car itself can be isolated for the first time, and its spectrum unambiguously analyzed. The X-ray emission of Eta Car in the 22-100 keV energy range is very hard (photon index around 1) and its luminosity is 7E33 erg/s. Conclusions : The observed emission is in agreement with the predictions of inverse Compton models, and corresponds to about 0.1% of the energy available in the wind collision. Eta Car is expected to be detected in the GeV energy range.Comment: 5 pages with 2 figures. Accepted as a Letter in Astronomy & Astrophysic

    Iran and American Security Policy in the Middle East

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    In October 1973 the Organization of Arab Petroleum Exporting Countries (OAPEC) sent shock waves through the industrialized world when it decreased the overall produc­tion of oil and embargoed the United States, Portugal, South Africa, and the Netherlands. The impact of these developments and a subsequent quantum rise in oil prices for the Western states and Japan was immediate and far reaching. On both sides of the Atlantic and in Tokyo there were fears of recession and even depression, the possibility of millions unemployed, and of massive deficits in the balance of payments

    A Flattened Protostellar Envelope in Absorption around L1157

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    Deep Spitzer IRAC images of L1157 reveal many of the details of the outflow and the circumstellar environment of this Class 0 protostar. In IRAC band 4, 8 microns, there is a flattened structure seen in absorption against the background emission. The structure is perpendicular to the outflow and is extended to a diameter of 2 arcminutes. This structure is the first clear detection of a flattened circumstellar envelope or pseudo-disk around a Class 0 protostar. Such a flattened morphology is an expected outcome for many collapse theories that include magnetic fields or rotation. We construct an extinction model for a power-law density profile, but we do not constrain the density power-law index.Comment: ApJL accepte

    Toward validating the Italian version of the “Spanish Burnout Inventory”: a preliminary study

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    AbstractOBJECTIVEThe aim of this study was to develop the Italian version of the Spanish Burnout Inventory (SBI) and to examine its psychometric properties within a sample of nursing staff.METHODThe study was cross-sectional and not randomized. The data were gathered using an anonymous, self-report questionnaire. The sample consisted of 391 staff nurses employed in three hospitals in the Northern Region of Italy To evaluate burnout, the SBI and the Maslach Burnout Inventory were administered.RESULTSAn Exploratory Factor Analysis showed a four-factor structure close to the expected one. All Cronbach's alpha values were satisfactory. Furthermore, correlations support the concurrent validity.CONCLUSIONOverall, the results of this study provided evidence that the SBI is an adequate instrument to study burnout in the Italian nursing sample and indicated the feeling of guilt as an important dimension to gauge the structure of this phenomenon

    Toward validating the Italian version of the "Spanish Burnout Inventory": a preliminary study

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    OBJETIVOO objetivo deste estudo foi desenvolver a versão italiana do SBI (Spanish Burnout Inventory) e analisar as suas propriedades psicométricas numa amostra de enfermeiros.MÉTODOO estudo foi de caráter transversal, e não randomizado. Os dados foram coletados através de um questionário autopreenchido de maneira anônima. A amostra foi composta por 391 enfermeiros funcionários de três hospitais de uma região do norte da Itália. Para avaliar o burnout, utilizou-se o Spanish Burnout Inventory e o Maslach Burnout Inventory.RESULTADOSOs resultados da Análise Fatorial Exploratória mostraram uma estrutura de quatro fatores, como era esperado. Todos os valores de alfa de Cronbach foram satisfatórios. Além disso, as correlações apoiar validade concorrente.CONCLUSÃONo geral, os resultados deste estudo forneceram evidências de que o SBI é um instrumento adequado para estudar o burnout numa amostra de enfermagem italiana e indicou que os sentimentos de culpa são uma dimensão importante para avaliar a estrutura do fenômeno.OBJECTIVEThe aim of this study was to develop the Italian version of the Spanish Burnout Inventory (SBI) and to examine its psychometric properties within a sample of nursing staff.METHODThe study was cross-sectional and not randomized. The data were gathered using an anonymous, self-report questionnaire. The sample consisted of 391 staff nurses employed in three hospitals in the Northern Region of Italy To evaluate burnout, the SBI and the Maslach Burnout Inventory were administered.RESULTSAn Exploratory Factor Analysis showed a four-factor structure close to the expected one. All Cronbach's alpha values were satisfactory. Furthermore, correlations support the concurrent validity.CONCLUSIONOverall, the results of this study provided evidence that the SBI is an adequate instrument to study burnout in the Italian nursing sample and indicated the feeling of guilt as an important dimension to gauge the structure of this phenomenon.OBJETIVODesarrollar la versión italiana del Spanish Burnout Inventory (SBI) y analizar sus propiedades psicométricas en una muestra de enfermeros.MÉTODOEstudio de carácter transversal y no randomizado. Los datos fueron recogidos mediante un cuestionario autorrellenado de manera anónima. La muestra estuvo compuesta de 391 enfermeros funcionarios de tres hospitales de una zona del norte de Italia. A fin de evaluar el burnout, se empleó el Spanish Burnout Inventory y el Maslach Burnout Inventory.RESULTADOSLos resultados del Análisis Factorial Exploratorio mostraron una estructura de cuatro factores, como era esperado. Todos los valores de alfa de Cronbach fueron satisfactorios. Además, las correlaciones apoyaron la validez concurrente.CONCLUSIÓNLos resultados de este estudio proporcionaron evidencias de que el SBI es un instrumento adecuado para estudiar el burnout en una muestra de enfermería italiana y señaló que los sentimientos de culpa son una dimensión importante para evaluar la estructura del fenómeno

    UV and X-Ray Monitoring of AG Draconis During the 1994/1995 Outbursts

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    The recent 1994-1995 active phase of AG Draconis has given us for the first time the opportunity to follow the full X-ray behaviour of a symbiotic star during two successive outbursts and to compare with its quiescence X-ray emission. With \ros observations we have discovered a remarkable decrease of the X-ray flux during both optical maxima, followed by a gradual recovering to the pre-outburst flux. In the UV the events were characterized by a large increase of the emission line and continuum fluxes, comparable to the behaviour of AG Dra during the 1980-81 active phase. The anticorrelation of X-ray/UV flux and optical brightness evolution is shown to very likely be due to a temperature decrease of the hot component. Such a temperature decrease could be produced by an increased mass transfer to the burning compact object, causing it to slowly expand to about twice its original size.Comment: 12 pages postscript incl. figures, Proc. of Workshop on Supersoft X-Ray Sources, to appear in Lecture Notes in Physics vol. 472 (1996
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