Search results for "371"
showing 10 items of 44 documents
Updated orbital ephemeris of the ADC source X 1822-371: a stable orbital expansion over 40 years
2019
The source X 1822-371 is an eclipsing compact binary system with a period close to 5.57 hr and an orbital period derivative $\dot{P}_{\rm orb}$ of 1.51(7)$\times 10^{-10}$ s s$^{-1}$. The very large value of $\dot{P}_{\rm orb}$ is compatible with a super-Eddington mass transfer rate from the companion star, as suggested by X-ray and optical data. The XMM-Newton observation taken in 2017 allows us to update the orbital ephemeris and verify whether the orbital period derivative has been stable over the last 40 yr. We added to the X-ray eclipse arrival times from 1977 to 2008 two new values obtained from the RXTE and XMM-Newton observations performed in 2011 and 2017, respectively. We estimate…
Freemasonry and Education in Contemporary Spain. Between Tolerance and Dogmatism
2017
Resumen:En este trabajo vamos a centrarnos casi en exclusiva en las iniciativas planteadas por diversas entidades masónicas, ya sean potencias, logias regionales o talleres, más que en personas exponiendo solamente algunas de las experiencias más relevantes y que ejemplifican mejor las intervenciones y actuaciones de la masonería española en relación con los enfoques descritos. La visibilidad que han alcanzado otras parcelas e interpretaciones del comportamiento, de los masones en particular y de las iniciativas de la masonería como institución, no nos deben ocultar la faceta desarrollada en torno a la educación. ¿Qué importancia tuvo el proceso formativo llevado a cabo en los talleres masó…
Semblanza de José Antonio Ayala Pérez
2014
José Antonio Ayala Pérez (1935-2014).
Spectral analysis of the low-mass X-ray pulsar 4U 1822-371: Reflection component in a high-inclination system
2021
Context. The X-ray source 4U 1822-371 is an eclipsing low-mass X-ray binary and X-ray pulsar, hosting a NS that shows periodic pulsations in the X-ray band with a period of 0.59 s. The inclination angle of the system is so high (80–85°) that in principle, it should be hard to observe both the direct thermal emission of the central object and the reflection component of the spectrum because they are hidden by the outer edge of the accretion disc. Despite the number of studies carried out on this source, many aspects such as the geometry of the system, its luminosity, and its spectral features are still debated. Aims. Assuming that the source accretes at the Eddington limit, the analysis perf…
Detailed study of the X-ray and optical/UV orbital ephemeris of X1822-371
2011
Recent studies of the optical/UV and X-ray ephemerides of X1822-371 have found some discrepancies in the value of the orbital period derivative. Because of the importance of this value in constraining the system evolution, we comprehensively analyse all the available optical/UV/X eclipse times of this source to investigate the origin of these discrepancies. We collected all previously published X-ray eclipse times from 1977 to 2008, to which we added the eclipse time observed by Suzaku in 2006. This point is very important to cover the time gap between the last RXTE eclipse time (taken in 2003) and the most recent Chandra eclipse time (taken in 2008). Similarly we collected the optical/UV e…
Spectral analysis and orbital evolution of Low Mass X-ray Binaries at high inclination
X-Ray binaries are gravitationally bound systems consisting of a compact object that accretes matter from a companion star; they are the most interesting objects of the sky, infact they allow to study the physics of matter in very extreme conditions of density, temperature or magnetic eld. So the determination of spectral and temporal properties of X-ray binaries plays an important role in understanding the processes involved in these systems. This project aims to understand the properties of binary systems, at high inclination (dipping and eclips- ing sources), containing neutron stars weakly magnetized. In the light curves of these systems it is possible to identify a variety of modulatio…
Discrete-valued-pulse optimal control algorithms: Application to spin systems
2015
International audience; This article is aimed at extending the framework of optimal control techniques to the situation where the control field values are restricted to a finite set. We propose generalizations of the standard GRAPE algorithm suited to this constraint. We test the validity and the efficiency of this approach for the inversion of an inhomogeneous ensemble of spin systems with different offset frequencies. It is shown that a remarkable efficiency can be achieved even for a very limited number of discrete values. Some applications in nuclear magnetic resonance are discussed.
Candau Chacon, María Luisa (coord.): Pasiones en femenino. Europa y América, 1600-1950
2020
Arendt y Heidegger ante el 'diluvio de Auschwitz'
2019
Tras las Conferencias de Bremen de Martin Heidegger y, más aún, tras los escritos de Hannah Arendt, el nacionalsocialismo ha sido reinterpretado como revelador de la modernidad técnica hasta el punto de que la institución nazi de los campos de concentración y exterminio se ha visto erigida en paradigma de esta modernidad. Esta visión, que podría llamarse posmoderna, de la historia del siglo xx merece ser cuestionada.1 ¿Cómo es posible que la obra de Heidegger, ese profesor y rector nacionalsocialista a quien se le prohíbe enseñar en 1945, haya tardado tanto tiempo en ser reconocida como un caso ejemplar, dentro del campo filosófico, de la visión del mundo o Weltanschauung nacionalsocialista…