A Radial Velocity Study of the Intermediate Polar EX Hydrae

A study on the intermediate polar EX Hya is presented, based on simultaneous photometry and high dispersion spectroscopic observations, during four consecutive nights. The strong photometric modulation related to with the 67-min spin period of the primary star is clearly present, as well as the narrow eclipses associated to the orbital modulation. Since our eclipse timings have been obtained almost 91,000 cycles since the last reported observations, we present new linear ephemeris, although we cannot rule out a sinusoidal variation suggested by previous authors. The system mainly shows double-peaked H$\alpha$, H$\beta$ and HeI $\lambda$5876 \AA emission lines. From the profile of the H$\alpha$ line, we find two components; one with a steep rise and velocities not larger than $\sim$1000 km s$^{-1}$ and another broader component extending up to $\sim$2000 km s$^{-1}$, which we interpret as coming mainly from the inner disc. A strong and variable hotspot is found and a stream-like structure is seen at times. We show that the best solution correspond to $K_1 = 58 \pm 5$ km s$^{-1}$ from H$\alpha$, from the two emission components, which are both in phase with the orbital modulation. We remark on a peculiar effect in the radial velocity curve around phase zero, which could be interpreted as a Rositter-MacLaughlin-like effect, which has been taken into account before deriving $K_1$. This value is compatible with the values found in high-resolution both in the ultraviolet and X-ray. We find: $M_{1} = 0.78 \pm 0.03$ M$_{\odot}$, $M_{2} = 0.10 \pm 0.02$ M$_{\odot}$ and $a = 0.67 \pm 0.01$ R$_{\odot}$. Doppler Tomography has been applied, to construct six Doppler tomograms for single orbital cycles spanning the four days of observations to support our conclusions. Our results indicate that EX Hya has a well formed disc and that the magnetosphere should extend only to about $3.75\,R_{\rm{WD}}$.Comment: 16 pages, 14 figures, accepted for publication in MNRA

Estratigrafía de la Cuenca Cenozoica de Chera (Valencia)

The Chera Basin, southern Iberian Ranges, has small size and elongated morphology trending NE-SW. It was developed during the Cenozoic across the important and transcurrent Requena-Mora de Ebro Fault, perpendicular to the Alpine directions and was refilled with alluvial and lacustrine sediments. It is a sinorogenic basin with an important sinsedimentary tectonic activity as it is shown by the unconformities between sediments, intracenozoic fracturate in stages, migration of the different facies across the main active border and the simetry of the refill with the depocentre located close to that oriental main active border

Symplectically aspherical manifolds with nontrivial π2 and with no Kähler metrics.

In a previous paper, the authors show some examples of compact symplectic solvman-ifolds, of dimension six, which are cohomologically KÄahler and they do not admit Kahler metrics because their fundamental groups cannot be the fundamental group of any compact Kahler manifold. Here we generalize such manifolds to higher dimension and, by using Au-roux symplectic submanifolds [3], we construct four-dimensional symplectically aspherical manifolds with nontrivial ¼2 and with no Kahler metrics

El paleógeno del sector suroccidental de la Cuenca del Duero: nueva división estratigráfica y controles sobre su sedimentación

A Paleogene four-fold stratigraphical division is proposed here as result from the detailed studies carried out during the elaboration of 22 sheets of the Geological Map of Spain (E. 1:50.000). This units (T.S.U.) are limited by regional discordances and they have a Upper Cretaceous to Oligocene ages. The previous stratigraphical schemes are rearranged due to the different stratigraphicalrelations observed between the lithostratigraphical units proPosed by other workers (Jiménez, 1970; Corrochano, 1977; Alonso, 1981 ...). An Upper Cretaceous-Paleocene age is assumed to T.S.U. MC which is mainly composed by siliciclastic sediments strongly silicified forming a FU megasequence. It is interpretated as braided streams that flowed downslope filling paleovalleys eroded onto Paleozoic materials. Mineralogical features point to a tropical climate. Lower Eocene (T.S.U. P1) is identified in the Salamanca area, where it was considered as lacking. It is composed by arkosic sediments forming a CU megasequence. Fossil faunas of this T.S.U. record a subtropical climate. It is observed a transition from high sinuosity streams to braided ones. T.S.U. P2 (Middle Eocene-Lower Oligocene) is composed of two lithostratigraphical units previously considered as bounded by a discordance (Alonso, 198 1). It has a subarkosic to lithic nature and forms a CU megasequence. This unit records a subtropical climate with short arid periods and is interpretated as braided streams showing an increasing stability and enviromental energy to the top. T.S.U. P3 (Upper Oligocene) is composed by arkosic sediments previously considered of Vallesian (Middle to Upper Miocene) age. They form a CU megasequence that records braided streams prograding basin ward from higher areas. Palinological associations and pedological features indicate an arid mediterranean climate with long arid periods and a short rainy season with strong floods. We consider that most of Lower Miocene sediments are of Paleogene age. They are afected by a widespread alteration profile developed along Lower Miocene that masked its more significative features. Sedimentological analysis of T.S.U. shows that its megasequentiality is related to the rates of tectonical uplift of source areas whereas a distensive regime developed in the sedimentation basin