SPITZER observations of the λ Orionis cluster. II. Disks around solar-type and low-mass stars

We present IRAC/MIPS Spitzer Space Telescope observations of the solar-type and the low-mass stellar population of the young (~5Myr) λ Orionis cluster. Combining optical and Two Micron All Sky Survey photometry, we identify 436 stars as probable members of the cluster. Given the distance (450 pc) and the age of the cluster, our sample ranges in mass from 2 M_⊙ to objects below the substellar limit. With the addition of the Spitzer mid-infrared data, we have identified 49 stars bearing disks in the stellar cluster. Using spectral energy distribution slopes, we place objects in several classes: non-excess stars (diskless), stars with optically thick disks, stars with “evolved disks” (with smaller excesses than optically thick disk systems), and “transitional disk” candidates (in which the inner disk is partially or fully cleared). The disk fraction depends on the stellar mass, ranging from ~6% for K-type stars (R_C − J 4). We confirm the dependence of disk fraction on stellar mass in this age range found in other studies. Regarding clustering levels, the overall fraction of disks in the λ Orionis cluster is similar to those reported in other stellar groups with ages normally quoted as ~5Myr

Caracterización de las orquídeas epífitas y sus forofitos en el parque ecológico universitario “José Mariano Mociño” de la Universidad Autónoma del Estado de México

During 2006, the abundance of the phorophyte/epiphytic orchid system was studied in the University ecological park “Jose Mariano Mociño” of the State of Mexico Autonomous University. A quantitative analysis of the phorphytes based on a centered quadrants method was made in the first stage, in the second one an abundance of ephifithic orchids was determined in a tridimensional environment based on own method by volume of treetops of the phorophyte that contained orchids. The results of the first stage shows predominance of encinos (Quercus spp) with a 1224 trees ha-1 density, a 12 370 m2 covery, 77% frequency and 2.35 of importance value. Second phase shows the abundance of orchids with significant differences (P < 0.05) between the sample groups as well between themselves showing an orchids community, with a significant statistical variation. The abundance of orchid/m3 phorophyte transects in the northern part was 0.094 and 0.048 in the southern part of the ecological park; the abundance of phorophytes and orchids was determined as an element to integrate conservation plans for the future in the plant community where they live.Se estudió, durante el 2006, la abundancia del sistema forofito/orquídeas epífitas en el Parque Ecológico Universitario “José Mariano Mociño” de la Universidad Autónoma del Estado de México, durante la primera fase se realizó el análisis cuantitativo de los forofitos con el método de cuadrantes centrados en un punto; en la segunda se determinó la abundancia de orquídeas epífitas en el entorno tridimensional basado en un método propio por volumen de copa del forofito que contenía orquídeas. Los resultados encontrados en la primera fase indican predominancia de encino (Quercus spp.) con una densidad de 1 224 árboles ha-1, cobertura de 12 370 m2 valor de importancia de 2.35. La segunda fase muestra la abundancia de orquídeas; existiendo diferencias (P < 0.05) significativas entre transectos y dentro de transectos, indicando una comunidad de orquídeas con una variación estadística significativa; la abundancia de orquídea/m3 , una frecuencia de 77%, y un por forofito enlos transectos de la parte norte fue de 0.094 y de 0.048 en los de la parte sur del parque ecológico; se determinó la abundancia de forofitos y orquídeas como un elemento para integrar planes de conservación a futuro en la comunidad vegetal donde habitan

Fractures of the tibial plateau. Influence of the type of fracture and precision of the articular reduction on the prognosis

Se realizó un estudio retrospectivo en 43 pacientes tratados de 45 fracturas de pilón tibial entre 1990 y 1998. Según la clasificación de Rüedi y Allgöwer 6 fracturas eran tipo I (13,3%), 6 tipo II (13,3%) y 33 tipo III (73,3%). El tratamiento realizado fue manipulación e inmovilización en botín de yeso en 8 fracturas, las seis del tipo I y dos del tipo II. En las 37 fracturas restantes se realizó osteotaxis y osteosíntesis. Los resultados clínicos obtenidos fueron excelentes-buenos en 27 de las fracturas (60%), valorados por parámetros objetivos, pero solo en 16 de las fracturas (35,5%) cuando se valoraron por parámetros subjetivos. Se apreciaron mejores resultados clínicos objetivos/subjetivos cuando se consiguió una buena reducción articular y cuanto menor era el grado de desplazamiento y hundimiento de la fractura; en estos casos fue más difícil obtener una buena reducción articular. En 2 fracturas (25%) tratadas conservadoramente y en 17 (46%) tratadas quirúrgicamente se presentó al menos una complicación. Las fracturas de pilón tibial son fracturas graves, por la frecuencia de lesiones de partes blandas y de otras estructuras con que se asocian y por los resultados mediocres derivados de su tratamiento, que son peores en las fracturas tipo III y cuando no se consigue una correcta reducción articular

Unexplored outflows in nearby low luminosity AGNs: the case of NGC 1052

Outflows play a central role in galaxy evolution shaping the properties of galaxies. Understanding outflows and their effects in low luminosity AGNs, such as LINERs, is essential (e.g. they are a numerous AGN population in the local Universe). We obtained VLT/MUSE and GTC/MEGARA optical IFS-data for NGC1052, the prototypical LINER. The stars are distributed in a dynamically hot disc, with a centrally peaked velocity dispersion map and large observed velocity amplitudes. The ionised gas, probed by the primary component is detected up to $\sim$30arcsec ($\sim$3.3 kpc) mostly in the polar direction with blue and red velocities ($\mid$V$\mid$$<$250 km/s). The velocity dispersion map shows a notable enhancement ($\sigma$$>$90 km/s) crossing the galaxy along the major axis of rotation in the central 10arcsec. The secondary component has a bipolar morphology, velocity dispersion larger than 150 km/s and velocities up to 660 km/s. A third component is detected but not spatially resolved. The maps of the NaD absorption indicate optically thick neutral gas with a velocity field consistent with a slow rotating disc ($\Delta$V = 77$\pm$12 km/s) but the velocity dispersion map is off-centred without any counterpart in the flux map. We found evidence of an ionised gas outflow with mass of 1.6$\pm$0.6 $\times$ 10$^{5}$ Msun, and mass rate of 0.4$\pm$0.2 Msun/yr. The outflow is propagating in a cocoon of gas with enhanced turbulence and might be triggering the onset of kpc-scale buoyant bubbles (polar emission). Taking into account the energy and kinetic power of the outflow (1.3$\pm$0.9 $\times$ 10$^{53}$ erg and 8.8$\pm$3.5 $\times$ 10$^{40}$ erg/s, respectively) as well as its alignment with both the jet and the cocoon, and that the gas is collisionally ionised, we consider that the outflow is jet-powered, although some contribution from the AGN is possible.Comment: A&A accepted 04/04/2022, 31 pages, 12 figures and 3 appendixe

Novel utility-scale photovoltaic plant electroluminescence maintenance technique by means of bidirectional power inverter controller

Nowadays, photovoltaic (PV) silicon plants dominate the growth in renewable energies generation. Utility-scale photovoltaic plants (USPVPs) have increased exponentially in size and power in the last decade and, therefore, it is crucial to develop optimum maintenance techniques. One of the most promising maintenance techniques is the study of electroluminescence (EL) images as a complement of infrared thermography (IRT) analysis. However, its high cost has prevented its use regularly up to date. This paper proposes a maintenance methodology to perform on-site EL inspections as efficiently as possible. First, current USPVP characteristics and the requirements to apply EL on them are studied. Next, an increase over the automation level by means of adding automatic elements in the current PV plant design is studied. The new elements and their configuration are explained, and a control strategy for applying this technique on large photovoltaic plants is developed. With the aim of getting on-site EL images on a real plant, a PV inverter has been developed to validate the proposed methodology on a small-scale solar plant. Both the electrical parameters measured during the tests and the images taken have been analysed. Finally, the implementation cost of the solution has been calculated and optimised. The results conclude the technical viability to perform on-site EL inspections on PV plants without the need to measure and analyse the panel defects out of the PV installation

Spitzer Observations of the Lambda Orionis cluster. II. Disks around solar-type and low mass stars

We present IRAC/MIPS Spitzer Space Telescope observations of the solar type and the low mass stellar population of the young (~5 Myr) Lambda Orionis cluster. Combining optical and 2MASS photometry, we identify 436 stars as probable members of the cluster. Given the distance (450 pc) and the age of the cluster, our sample ranges in mass from 2 solar mass to objects below the substellar limit. With the addition of the Spitzer mid-infrared data, we have identified 49 stars bearing disks in the stellar cluster. Using spectral energy distribution (SED) slopes, we place objects in several classes: non-excess stars (diskless), stars with optically thick disks, stars with ``evolved disks''( with smaller excesses than optically thick disk systems), and ``transitional disks'' candidates (in which the inner disk is partially or fully cleared). The disk fraction depends on the stellar mass, ranging from ~6% for K type stars (Rc-J<2) to ~27% for stars with spectral type M5 or later (Rc-J>4). We confirm the dependence of disk fraction on stellar mass in this age range found in other studies. Regarding clustering levels, the overall fraction of disks in the Lambda Orionis cluster is similar to those reported in other stellar groups with ages normally quoted as ~5 Myr.Comment: 37 pages, 11 Figures and 3 Tables, Accepted for publication in The Astrophysical Journa

HADES RV Programme with HARPS-N at TNG. VII. Rotation and activity of M-Dwarfs from time-series high-resolution spectroscopy of chromospheric indicators

We aim to investigate the presence of signatures of magnetic cycles and rotation on a sample of 71 early M-dwarfs from the HADES RV programme using high-resolution time-series spectroscopy of the Ca II H & K and Halpha chromospheric activity indicators, the radial velocity series, the parameters of the cross correlation function and the V-band photometry. We used mainly HARPS-N spectra, acquired over four years, and add HARPS spectra from the public ESO database and ASAS photometry light-curves as support data, extending the baseline of the observations of some stars up to 12 years. We provide log(R'hk) measurements for all the stars in the sample, cycle length measurements for 13 stars, rotation periods for 33 stars and we are able to measure the semi-amplitude of the radial velocity signal induced by rotation in 16 stars. We complement our work with previous results and confirm and refine the previously reported relationships between the mean level of chromospheric emission, measured by the log(R'hk), with the rotation period, and with the measured semi-amplitude of the activity induced radial velocity signal for early M-dwarfs. We searched for a possible relation between the measured rotation periods and the lengths of the magnetic cycle, finding a weak correlation between both quantities. Using previous v sin i measurements we estimated the inclinations of the star's poles to the line of sight for all the stars in the sample, and estimate the range of masses of the planets GJ 3998 b and c (2.5 - 4.9 Mearth and 6.3 - 12.5 Mearth), GJ 625 b (2.82 Mearth), GJ 3942 b (7.1 - 10.0 Mearth) and GJ 15A b (3.1 - 3.3 Mearth), assuming their orbits are coplanar with the stellar rotation.Comment: 19 pages, 16 figures, 10 table

The HADES RV Programme with HARPS-N@TNG II. Data treatment and simulations

The distribution of exoplanets around low-mass stars is still not well understood. Such stars, however, present an excellent opportunity of reaching down to the rocky and habitable planet domains. The number of current detections used for statistical purposes is still quite modest and different surveys, using both photometry and precise radial velocities, are searching for planets around M dwarfs. Our HARPS-N red dwarf exoplanet survey is aimed at the detection of new planets around a sample of 78 selected stars, together with the subsequent characterization of their activity properties. Here we investigate the survey performance and strategy. From 2700 observed spectra, we compare the radial velocity determinations of the HARPS-N DRS pipeline and the HARPS-TERRA code, we calculate the mean activity jitter level, we evaluate the planet detection expectations, and we address the general question of how to define the strategy of spectroscopic surveys in order to be most efficient in the detection of planets. We find that the HARPS-TERRA radial velocities show less scatter and we calculate a mean activity jitter of 2.3 m/s for our sample. For a general radial velocity survey with limited observing time, the number of observations per star is key for the detection efficiency. In the case of an early M-type target sample, we conclude that approximately 50 observations per star with exposure times of 900 s and precisions of about 1 m/s maximizes the number of planet detections