Temperature and kinematics of protoclusters with intermediate and high-mass stars: the case of IRAS 05345+3157

We have mapped at small spatial scales the temperature and the velocity field in the protocluster associated with IRAS 05345+3157, which contains both intermediate-/high-mass protostellar candidates and starless condensations, and is thus an excellent location to investigate the role of massive protostars on protocluster evolution. We observed the ammonia (1,1) and (2,2) inversion transitions with the VLA. Ammonia is the best thermometer for dense and cold gas, and the observed transitions have critical densities able to trace the kinematics of the intracluster gaseous medium. The ammonia emission is extended and distributed in two filamentary structures. The starless condensations are colder than the star-forming cores, but the gas temperature across the whole protocluster is higher (by a factor of ~1.3-1.5) than that measured typically in both infrared dark clouds and low-mass protoclusters. The non-thermal contribution to the observed line broadening is at least a factor of 2 larger than the expected thermal broadening even in starless condensations, contrary to the close-to-thermal line widths measured in low-mass quiescent dense cores. The NH3-to-N2H+ abundance ratio is greatly enhanced (a factor of 10) in the pre--stellar core candidates, probably due to freeze-out of most molecular species heavier than He. The more massive and evolved objects likely play a dominant role in the physical properties and kinematics of the protocluster. The high level of turbulence and the fact that the measured core masses are larger than the expected thermal Jeans masses indicate that turbulence likely was an important factor in the initial fragmentation of the parental clump.Comment: 13 pages (with Appendix), 11 figure

Deuteration as an evolutionary tracer in massive-star formation

Theory predicts, and observations confirm, that the column density ratio of a molecule containing D to its counterpart containing H can be used as an evolutionary tracer in the low-mass star formation process. Since it remains unclear if the high-mass star formation process is a scaled-up version of the low-mass one, we investigated whether the relation between deuteration and evolution can be applied to the high-mass regime. With the IRAM-30m telescope, we observed rotational transitions of N2D+ and N2H+ and derived the deuterated fraction in 27 cores within massive star-forming regions understood to represent different evolutionary stages of the massive-star formation process. Results. Our results clearly indicate that the abundance of N2D+ is higher at the pre-stellar/cluster stage, then drops during the formation of the protostellar object(s) as in the low-mass regime, remaining relatively constant during the ultra-compact HII region phase. The objects with the highest fractional abundance of N2D+ are starless cores with properties very similar to typical pre-stellar cores of lower mass. The abundance of N2D+ is lower in objects with higher gas temperatures as in the low-mass case but does not seem to depend on gas turbulence. Our results indicate that the N2D+-to-N2H+ column density ratio can be used as an evolutionary indicator in both low- and high-mass star formation, and that the physical conditions influencing the abundance of deuterated species likely evolve similarly during the processes that lead to the formation of both low- and high-mass stars.Comment: Accepted by A&AL, 4 pages, 2 figures, 2 appendices (one for Tables, one for additional figures

Mid-J CO Emission in Nearby Seyfert Galaxies

We study for the first time the complete sub-millimeter spectra (450 GHz to 1550 GHz) of a sample of nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) onboard Herschel. The CO ladder (from Jup = 4 to 12) is the most prominent spectral feature in this range. These CO lines probe warm molecular gas that can be heated by ultraviolet photons, shocks, or X-rays originated in the active galactic nucleus or in young star-forming regions. In these proceedings we investigate the physical origin of the CO emission using the averaged CO spectral line energy distribution (SLED) of six Seyfert galaxies. We use a radiative transfer model assuming an isothermal homogeneous medium to estimate the molecular gas conditions. We also compare this CO SLED with the predictions of photon and X-ray dominated region (PDR and XDR) models.Comment: Proceedings of the Torus Workshop 2012 held at the University of Texas at San Antonio, 5-7 December 2012. C. Packham, R. Mason, and A. Alonso-Herrero (eds.); 6 pages, 3 figure

Geofísica ambiental: técnicas no destructivas para el reconocimiento de zonas contaminadas por vertidos

Industrial countries face the consequences of decades of inappropiate handling of hazardous waste. The dumping of al1 types of hazardous materials has been ongoing in most industrialised countries for hundreds of years. Large quantities of industrial and other waste material have been buried in landfill sites. A relatively large number of these lack reliable man-made or natural geological barriers and toxic fluids are scaping and polluting the groundwater. The problem is greatly aggravated when a soil covenng is placed over the waste and there is no information about the dumping practices used in the past. One of the first tasks in any remedial action is to delineate the physical extent of the sites and its encroachment into the surrounding area. Test borings and limited excavations are very valuable but the information obtained is not continuous and dheir destructive nature makes it possible that waste could inadvertently be released during the probing phase. In this regard, both borehole drilling and excavation are very dangerous to workers and the environment and expensive and tedious to conduct.Many of these problems may be alleviated by using a geophysical assisted system approach to determine where the pollutants will go in the subsurface, gain more complete understanding of site conditions and asses the optimal placement of exploration drills and monitonng wells. At hazardous waste sites, the main objectives must commonly include:- Determine the presence, location, distribution, depth and composition of possible buried wastes.- Determine the presence and extent of contaminant and leachate plumes within the unsaturated and saturated zones.- Characterise and asses the local (and regional) geohydrologic regime for groundwater flow paterns, recharge areas and localised permeable pathways

Iron and Nickel spectral opacity calculations in conditions relevant for pulsating stellar envelopes and experiments

Seismology of stars is strongly developing. To address this question we have formed an international collaboration OPAC to perform specific experimental measurements, compare opacity calculations and improve the opacity calculations in the stellar codes [1]. We consider the following opacity codes: SCO, CASSANDRA, STA, OPAS, LEDCOP, OP, SCO-RCG. Their comparison has shown large differences for Fe and Ni in equivalent conditions of envelopes of type II supernova precursors, temperatures between 15 and 40 eV and densities of a few mg/cm3 [2, 3, 4]. LEDCOP, OPAS, SCO-RCG structure codes and STA give similar results and differ from OP ones for the lower temperatures and for spectral interval values [3]. In this work we discuss the role of Configuration Interaction (CI) and the influence of the number of used configurations. We present and include in the opacity code comparisons new HULLAC-v9 calculations [5, 6] that include full CI. To illustrate the importance of this effect we compare different CI approximations (modes) available in HULLAC-v9 [7]. These results are compared to previous predictions and to experimental data. Differences with OP results are discussed.Comment: 4 pages, 3 figures, conference Inertial Fusion Sciences and Applications, Bordeaux, 12th to 16th September 2011; EPJ web of Conferences 201

Diseño de un seguidor solar de dos ejes para celdas fotovoltaicas

En este trabajo se presenta el desarrollo de un seguidor solar de dos ejes para aplicaciones solares, tales como celdas fotovoltaicas. Se detallan sus componentes, así como el funcionamiento de cada uno de ellos. El sistema ha demostrado un rendimiento satisfactorio, lo que permite una mayor absorción de los rayos solares.This paper presents the development of a two-axis solar tracker for solar applications, such as photovoltaic cells. It details its constituent parts as well as the operation of each of them. The system has demonstrated satisfactory performance, allowing greater uptake of solar rays.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

The wideband backend at the MDSCC in Robledo. A new facility for radio astronomy at Q- and K- bands

The antennas of NASA's Madrid Deep Space Communications Complex (MDSCC) in Robledo de Chavela are available as single-dish radio astronomical facilities during a significant percentage of their operational time. Current instrumentation includes two antennas of 70 and 34 m in diameter, equipped with dual-polarization receivers in K (18 - 26 GHz) and Q (38 - 50 GHz) bands, respectively. We have developed and built a new wideband backend for the Robledo antennas, with the objectives (1) to optimize the available time and enhance the efficiency of radio astronomy in MDSCC; and (2) to tackle new scientific cases impossible to that were investigated with the old, narrow-band autocorrelator. The backend consists of an IF processor, a FFT spectrometer (FFTS), and the software that interfaces and manages the events among the observing program, antenna control, the IF processor, the FFTS operation, and data recording. The whole system was end-to-end assembled in August 2011, at the start of commissioning activities, and the results are reported in this paper. Frequency tunings and line intensities are stable over hours, even when using different synthesizers and IF channels; no aliasing effects have been measured, and the rejection of the image sideband was characterized. The first setup provides 1.5 GHz of instantaneous bandwidth in a single polarization, using 8192 channels and a frequency resolution of 212 kHz; upgrades under way include a second FFTS card, and two high-resolution cores providing 100 MHz and 500 MHz of bandwidth, and 16384 channels. These upgrades will permit simultaneous observations of the two polarizations with instantaneous bandwidths from 100 MHz to 3 GHz, and spectral resolutions from 7 to 212 kHz.Comment: 9 pages, 8 figures. Accepted to Astronomy and Astrophysic