Determination of the basic parameters of the dwarf nova EY Cygni

High-dispersion spectroscopy of EY Cyg obtained from data spanning twelve years show, for the first time, the radial velocity curves from both emission and absorption line systems, yielding semi-amplitudes K_{em}=24+/- 4 km s^-1 and K_{abs}=54+/- 2 km s^-1. The orbital period of this system is found to be 0.4593249(1)d. The masses of the stars, their mass ratio and their separation are found to be M_1 sin^3 i = 0.015+/-0.002 M_sun, M_2 sin^3 i = 0.007+/-0.002 M_sun, q = K_1/K_2 = M_2/M_1 = 0.44+/-0.02 and a sin i = 0.71+/-0.04 R_sun. We also found that the spectral type of the secondary star is around K0,consistent with an early determination by Kraft(1962). From the spectral type of the secondary star and simple comparisons with single main sequence stars, we conclude that the radius of the secondary star is about 30 per cent larger than a main sequence star of the same mass. We also present VRI CCD photometric observations, some of them simultaneous with the spectroscopic runs. The photometric data shows several light modulations, including a sinusoidal behaviour with twice the frequency of the orbital period, characteristic of the modulation coming from an elongated, irradiated secondary star. Low and high states during quiescence are also detected and discussed. From several constrains, we obtain tight limits for the inclination angle of the binary system between 13 and 15 degrees, with a best value of 14 degrees obtained from the sinusoidal light curve analysis. From the above results we derive masses M_1 = 1.10+/-0.09 M_sun, M_2 = 0.49+/-0.09 M_sun, and a binary separation a = 2.9+/- 0.1 R_sun.Comment: 14 pages, 14 figures, accepted for publication on A&

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

Mixed-mode impedance and reflection coefficient of two-port devices

From the point of view of mixed-mode scattering parameters, Smm, a two-port device can be excited using different driving conditions. Each condition leads to a particular set of input reflection and input impedance coefficient definitions that should be carefully applied depending on the type of excitation and symmetry of the two-port device. Therefore, the aim of this paper is to explain the general analytic procedure for the evaluation of such reflection and impedance coefficients in terms of mixed-mode scattering parameters. Moreover, the driving of a two-port device as a one-port device is explained as a particular case of a two-port mixed-mode excitation using a given set of mixed-mode loads. The theory is applied to the evaluation of the quality factor, Q, of symmetrical and non- symmetrical inductors.Ministerio de Innovación y Ciencia TEC2010-14825/MIC, TEC2010-21484Junta de Andalucía TIC-253

On the Orbital Period of the Intermediate Polar 1WGA J1958.2+3232

Recently, Norton et al. 2002, on the basis of multiwavelength photometry of 1WGA J1958.2+3232, argued that the -1 day alias of the strongest peak in the power spectrum is the true orbital period of the system, casting doubts on the period estimated by Zharikov et al. 2001. We re-analyzed this system using our photometric and spectroscopic data along with the data kindly provided by Andy Norton and confirm our previous finding. After refining our analysis we find that the true orbital period of this binary system is 4.35h.Comment: 4 pages, 5 figures, Accepted for publication in A&A Letter

Diálogo interdisciplinar: aproximación biosocial a la parentalidad. 1ª parte

Se relaciona el conjunto de elementos conceptuales y teóricos barajados en las discusiones de los últimos cinco años sobre reproducción y crianza como tema de estudio emergente en respuesta a su diversidad y problemática en la sociedad actual. Se refieren a los encuentros promovidos por el grupo de investigación del Parentesco getp-GRAFO de la UAB con la participación de otros grupos e investigadores que vienen trabajando sobre este tema. Se agrupan en torno a un proyecto multidisciplinar que aborda las conexiones de diversas disciplinas con la Parentalidad como propiedad biopsicosocial de los humanos y otras especies filogenéticamente emparentadas. Responde a la necesidad de encontrar vías de comunicación a partir de las trayectorias y formaciones dispares, lo que facilitará nuevas colaboraciones.Palabras clave: Parentalidad, cuidados parentales, biología evolutiva, paleoantropología, origen de la cultura.AbstractThis text relates to a set of conceptual and theoretical elements posed in the discussions of the last five years on reproduction and childrearing as an emergent subject of study.This work emerges in response to the complexity of these issues and the problems surrounding them in today’s society. The work is promoted by the research group getp-GRAFO at the UAB, with the collaboration of other groups and researchers who have been regularly working on that issue. They gather around a multidisciplinary project that addresses connections between different disciplines and parenthood as a biopsychosocial property of human beings and other phylogenetically related species. It speaks to the need to open new communication paths based on different trajectories and backgrounds, which will ease further cooperation.Keywords: Parenthood, parental care, evolutionary biology, Paleoanthropology, origin of culture

El Corpus en Granada : (evocación de sus fiestas)

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 201