The supergiant B[e] star LHA 115-S 18 - binary and/or luminous blue variable?

Context. The mechanism by which supergiant (sg)B[e] stars support cool, dense dusty discs/tori and their physical relationship with other evolved, massive stars such as luminous blue variables is uncertain. Aims. In order to investigate both issues we have analysed the long term behaviour of the canonical sgB[e] star LHA 115-S 18. Methods. We employed the OGLE II-IV lightcurve to search for (a-)periodic variability and supplemented these data with new and historic spectroscopy. Results. In contrast to historical expectations for sgB[e] stars, S18 is both photometrically and spectroscopically highly variable. The lightcurve is characterised by rapid aperiodic ` aring' throughout the 16 years of observations. Changes in the high excitation emission line component of the spectrum imply evolution in the stellar temperature - as expected for luminous blue variables - although somewhat surprisingly, spectroscopic and photometric variability appears not to be correlated. Characterised by emission in low excitation metallic species, the cool circumstellar torus appears largely unaffected by this behaviour. Finally, in conjunction with intense, highly variable He ii emission, X-ray emission implies the presence of an unseen binary companion. Conclusions. S18 provides observational support for the putative physical association of (a subset of) sgB[e] stars and luminous blue variables. Given the nature of the circumstellar environment of S18 and that luminous blue variables have been suggested as SN progenitors, it is tempting to draw a parallel to the progenitors of SN1987A and SN2009ip. Moreover the likely binary nature of S18 strengthens the possibility that the dusty discs/tori that characterise sgB[e] stars are the result of binary-driven mass-loss; consequently such stars may provide a window on the short lived phase of mass-transfer in massive compact binaries.

Antonio Maura y el papel del II Reich en las negociaciones hispano-francesas sobre Marruecos de 1903-1904

En la primera parte del artículo se aborda el problema que ha de afrontar el estadista Antonio Maura al convertirse en el jefe del gobierno español, a finales de 1903 y consistente en concluir el proceso de negociación sobre Marruecos entablado con Francia desde 1901. Se resalta el carácter continuista del ideario colonial de Maura con respecto al del anterior líder conservador, Silvela, y la preponderancia de cuestiones como la seguridad nacional como motivadoras de dicho ideario. En la segunda parte, se explica la apelación del gobierno maurista a una ayuda por parte de Alemania, en función de movimientos previos de la diplomacia germana que se había interesado por controlar una parte del Marruecos español, o por conseguir compensaciones en Fernando Po. Finalmente se analiza el intento de Berlín de instrumentalizar al gobierno Maura en el curso de las conversaciones hispano-francesas sobre el Imperio jerifiano.