Probing large-scale wind structures in Vela X–1 using off-states with INTEGRAL

Vela X–1 is the prototype of the class of wind-fed accreting pulsars in high-mass X-ray binaries hosting a supergiant donor. We have analysed in a systematic way 10 years of INTEGRAL data of Vela X–1 (22–50 keV) and we found that when outside the X-ray eclipse, the source undergoes several luminosity drops where the hard X-rays luminosity goes below ∼3 × 1035 erg s−1, becoming undetected by INTEGRAL. These drops in the X-ray flux are usually referred to as ‘off-states’ in the literature. We have investigated the distribution of these off-states along the Vela X–1 ∼ 8.9 d orbit, finding that their orbital occurrence displays an asymmetric distribution, with a higher probability to observe an off-state near the pre-eclipse than during the post-eclipse. This asymmetry can be explained by scattering of hard X-rays in a region of ionized wind, able to reduce the source hard X-ray brightness preferentially near eclipse ingress. We associate this ionized large-scale wind structure with the photoionization wake produced by the interaction of the supergiant wind with the X-ray emission from the neutron star. We emphasize that this observational result could be obtained thanks to the accumulation of a decade of INTEGRAL data, with observations covering the whole orbit several times, allowing us to detect an asymmetric pattern in the orbital distribution of off-states in Vela X–1.

An XMM-Newton view of FeKα in high-mass X-ray binaries

We present a comprehensive analysis of the whole sample of available XMM-Newton observations of high-mass X-ray binaries (HMXBs) until August 2013, focusing on the FeKα emission line. This line is key to better understanding the physical properties of the material surrounding the X-ray source within a few stellar radii (the circumstellar medium). We collected observations from 46 HMXBs and detected FeKα in 21 of them. We used the standard classification of HMXBs to divide the sample into different groups. We find that (1) different classes of HMXBs display different qualitative behaviours in the FeKα spectral region. This is visible especially in SGXBs (showing ubiquitous Fe fluorescence but not recombination Fe lines) and in γ Cass analogues (showing both fluorescent and recombination Fe lines). (2) FeKα is centred at a mean value of 6.42 keV. Considering the instrumental and fits uncertainties, this value is compatible with ionization states that are lower than Fe xviii. (3) The flux of the continuum is well correlated with the flux of the line, as expected. Eclipse observations show that the Fe fluorescence emission comes from an extended region surrounding the X-ray source. (4) We observe an inverse correlation between the X-ray luminosity and the equivalent width of FeKα (EW). This phenomenon is known as the X-ray Baldwin effect. (5) FeKα is narrow (σline< 0.15 keV), reflecting that the reprocessing material does not move at high speeds. We attempt to explain the broadness of the line in terms of three possible broadening phenomena: line blending, Compton scattering, and Doppler shifts (with velocities of the reprocessing material V ~ 1000 km s-1). (6) The equivalent hydrogen column (NH) directly correlates to the EW of FeKα, displaying clear similarities to numerical simulations. It highlights the strong link between the absorbing and the fluorescent matter. (7) The observed NH in supergiant X-ray binaries (SGXBs) is in general higher than in supergiant fast X-ray transients (SFXTs). We suggest two possible explanations: different orbital configurations or a different interaction compact object – wind. (8) Finally, we analysed the sources IGR J16320-4751 and 4U 1700-37 in more detail, covering several orbital phases. The observed variation in NH between phases is compatible with the absorption produced by the wind of their optical companions. The results clearly point to a very important contribution of the donor’s wind in the FeKα emission and the absorption when the donor is a supergiant massive star.

Orbital phase-resolved spectroscopy of 4U 1538−52 with MAXI

Context. 4U 1538−52, an absorbed high mass X-ray binary with an orbital period of ~3.73 days, shows moderate orbital intensity modulations with a low level of counts during the eclipse. Several models have been proposed to explain the accretion at different orbital phases by a spherically symmetric stellar wind from the companion. Aims. The aim of this work is to study both the light curve and orbital phase spectroscopy of this source in the long term. In particular, we study the folded light curve and the changes in the spectral parameters with orbital phase to analyse the stellar wind of QV Nor, the mass donor of this binary system. Methods. We used all the observations made from the Gas Slit Camera on board MAXI of 4U 1538−52 covering many orbits continuously. We obtained the good interval times for all orbital phase ranges, which were the input for extracting our data. We estimated the orbital period of the system and then folded the light curves, and we fitted the X-ray spectra with the same model for every orbital phase spectrum. We also extracted the averaged spectrum of all the MAXI data available. Results. The MAXI spectra in the 2–20 keV energy range were fitted with an absorbed Comptonisation of cool photons on hot electrons. We found a strong orbital dependence of the absorption column density but neither the fluorescence iron emission line nor low energy excess were needed to fit the MAXI spectra. The variation in the spectral parameters over the binary orbit were used to examine the mode of accretion onto the neutron star in 4U 1538−52. We deduce a best value of Ṁ/v∞ = 0.65 × 10-9M⊙ yr-1/ (km s-1) for QV Nor.

On the Radial Onset of Clumping in the Wind of the B0I Massive Star QV Nor

We present an analysis of a 78 ks Chandra high-energy transmission gratings observation of the B0I star QV Nor, the massive donor of the wind-accreting pulsar 4U1538−52. The neutron star (NS) orbits its companion in a very close orbit (r < 1.4R*, in units of the stellar radii), thereby allowing probing of the innermost wind regions. The flux of the Fe Kα line during eclipse reduces to only ∼30% of the flux measured out of eclipse. This indicates that the majority of Fe fluorescence must be produced in regions close to the NS, at distances smaller than 1R* from its surface. The fact that the flux of the continuum decreases to only ∼3% during eclipse allows for a high contrast of the Fe Kα line fluorescence during eclipse. The line is not resolved and centered at 1.9368 0.0018 l = 0.0032 - + Å. From the inferred plasma speed limit of v < c l < 800 l D km s−1 and range of ionization parameters of log 1, 2 x = [- ], together with the stellar density profile, we constrain the location of the cold, dense material in the stellar wind of QV Nor using simple geometrical considerations. We then use the Fe Kα line fluorescence as a tracer of wind clumps and determine that these clumps in the stellar wind of QV Nor (B0I) must already be present at radii r < 1.25R*, close to the photosphere of the star.

Annotated almanac, 1766

Almanac containing three laid-in pages with handwritten notes and a few sporadic corrections to the rising and setting times of the moon on the calendar pages. The three laid-in pages consist of a small scrap of paper with the weights of the family, and two folded pages with notes about a lunar eclipse on August 20, 1766.

The Summary of a Course of Experimental Philosophical Lectures, 1746-1747

Leather hardcover notebook containing a handwritten copy of John Winthrop's course of experimental and philosophical lectures presented between March 10, 1746 and June 16, 1746. The first one-hundred pages of the volume are divided into twenty chapters which were presented in thirty-three lectures. The chapters contain text and diagrams on mechanical powers, the lever, the pulley, the axis in peritrochio, the inclined plane, the wedge, the screw, compound engines, the laws of motion, gravity, attraction of cohesion, the power of repulsion, magnetism, fluids, electricity, opticks, and astronomy. There is a five-page addenda to the course summary added in 1747, and a sixty-page text titled "The Method of Astronomical calculations" containing thirteen problems related to calculating distances with a list of astronomical characters, and followed with charts related to the eclipse of Jupiter's satellites.

Did Egypt's Parliamentary Election just trump citizens’ rights? Arab Citizenship Review No. 12, 19 November 2015

Since the Muslim Brotherhood rule was toppled in July 2013, the regime of President Abd al-Fattah al-Sisi has strived to consolidate his one-man rule; he painted the political opposition and civil society as traitors and foreign agents and exploited the fight against terrorism to suppress freedom of expression, justify a crackdown on the press, eclipse justice in courtrooms, throw thousands in prison, and tighten his grip on police forces. The regime has postponed parliamentary elections for some time, while it marginalised and weakened the non-Islamist political parties that helped Sisi take power. He did so by promoting electoral lists with candidates who are loyal to the president, to ensure control over the new assembly and by obstructing any political alliance that could form an opposition. At the same time, the security apparatus has been given free rein to control the public sphere and engineer the electoral process. This may ultimately lead to a parliament that includes no advocates for rights and liberties, which is particularly significant since the incoming assembly will review the huge amount of legislation that President Sisi has issued in the absence of a parliament. In addition, shortly before elections, President Sisi raised questions about the constitution, calling for it to be amended to reduce the powers of the parliament and increase those of the president. It is thus clear that Sisi seeks not only to consolidate his regime, without political opposition, but to free his rule of any effective oversight from society or parliament.

Optimização de rotas na recolha de leite

O presente relatório tem por objectivo apresentar e descrever de forma detalhada o projecto “Optimização de rotas na recolha de leite”. Este projecto foi conduzido no âmbito do estágio curricular, realizado na parte não-lectiva do Mestrado em Sistemas de Informação de Gestão, do Instituto Superior de Contabilidade e Administração de Coimbra, tendo decorrido na empresa Lacticoop entre 03 de Outubro de 2011 e 27 de Julho de 2012. O projecto surge da necessidade da empresa optimizar as suas rotas de recolha de leite. Essa optimização pode ser subdividida em duas partes distintas: i) a recolha de dados, características e processos relativos à empresa e aos sistemas com que labora; ii) e o desenvolvimento do software necessário para a optimização de uma componente desses sistemas, associada ao processo de recolha de leite. O primeiro ponto envolve a recolha de informação sobre a política interna da empresa, a recolha de dados acerca dos veículos, rotas, consumos e condutores, assim como o levantamento de procedimentos e tecnologias utilizadas. O segundo ponto envolve a modelação do problema em estudo, o levantamento das necessidades de software para implementar o sistema de informação, a avaliação de soluções de software e desenvolvimento/adaptação da aplicação informática, assim como a implementação do software desenvolvido / adaptado e testes. Actualmente a empresa não dispõe de qualquer automatismo para a definição de rotas, sendo o processo de escalonamento de rotas feito manualmente. Este processo é bastante moroso e complexo, envolvendo a troca de informações entre o gestor e os condutores das viaturas. É um processo gradual, numa sequência de detecção de erros e correcção desses mesmos erros. Esta metodologia conduz a soluções bastante ineficientes, desde logo pela desactualização das soluções relativamente à efemeridade dos dados, especialmente ao nível de quantidades de recolha do produto. A razão da escolha de um sistema informático que permita optimizar as rotas prende-se essencialmente com a rapidez na obtenção de soluções e na capacidade de integração de dados actualizados. Este processo recorre a técnicas e modelos de optimização que envolvem o problema de Rotas de Veículos (Vehicle Routing Problem), sendo, em geral, um problema de difícil resolução em função do número de clientes envolvidos. Todavia, trata-se de um sistema que traz enormes benefícios no apoio ao processo de decisão por parte do gestor. Neste estágio pretendeu-se, como objectivo principal, desenvolver uma aplicação que permita optimizar as rotas dos veículos envolvidos no processo de recolha de leite. Os benefícios do sistema na diminuição de distâncias percorridas pelas viaturas de recolha e no aumento da eficiência do sistema de transportes, serão evidenciados no trabalho desenvolvido. A aplicação foi criada no software Eclipse (utilizando a linguagem Java). Na primeira fase do projecto estava previsto monitorizar as rotas e consumos dos veículos através da tecnologia de geo-posicionamento por satélite (GPS), de forma a atribuir comissões sobre a poupança de combustível aos condutores dos veículos. Não foi possível concluir esta fase devido à inexistência dessa tecnologia nas viaturas e pelo facto de a empresa ter retirado essa prioridade a esse investimento.

Professional papers of the Signal service, no. 1-16, 18.

No. 17 forms pt.2 (app.71) of the Annual report of the chief signal officer for the year 1885 (Annual report of the secretary of war ... 1885, vol. IV, pt. 2) It is issued also in the Congressional series, no. 2375 (49th Cong., 1st sess. House. Ex. doc.1, pt.2).

[De los eclipses: no 15 del cuestionario] : discurso leído en el acto solemne de recibir la investidura de doctor en la Facultad de Ciencias, Sección de Ciencias Exactas /

Mode of access: Internet.

Report on caffeine /

"September 1980."

Primera parte De las Differencias de libros que ay en el vniuerso /

Ruiz Fidalgo,

New methods of alkalimetry, and of determining the commercial value of acids and manganese.

Translation of Neue Verfahrungsweisen zur Prüfung der Pottasche und Soda, der Aschen, der Säuren, insbesondere des Essigs so wie Braunsteins auf ihren wahren Gehalt und Handelswerth.

Recherches astronomiques de l'Observatoire d'Utrecht.

Ceased with volume 18:2. Superseded by the Bullletin of the Astronomical Institutes of the Netherlands, Supplement series.

British Manufacturing Industries. Edited by G.P. Bevan.

Imperfect; wanting the volume entitled, "Paper, by Prof. Archer, Printing, by Joseph Hatton, etc."