New detections of H2O masers in planetary nebulae and post-AGB stars using the Robledo-70m antenna

Aims: We investigated the possible relationship between the evolutionary stage of post-AGB stars and planetary nebulae (PNe) and the presence of water masers in their envelopes. Methods: We have used NASA's 70-m antenna in Robledo de Chavela (Spain) to search for the water maser transition at 22235.08 MHz, towards a sample of 105 sources with IRAS colour characteristic of post-AGB stars and PNe at declination >-32 deg. 83% of the sources in the sample are post-AGB stars, 15% PNe or PN candidates, while only 2% seem to be HII regions. Results: We have detected five water masers, of which four are reported for the first time: two in PNe (IRAS 17443-2949 and IRAS 18061-2505), a ``water fountain'' in a post-AGB star (IRAS 16552-3050), and one in a source previously catalogued as a PN, but whose classification is uncertain (IRAS 17580-3111). Conclusions: The unexpected detections of water masers in two objects among the small subset of PNe led us to suggest that the PNe harbouring water masers are a special type of massive, rapidly evolving PNe.Comment: 15 pages, 7 figures. Accepted for publication in Astronomy and Astrophysic

Single-file diffusion on self-similar substrates

We study the single file diffusion problem on a one-dimensional lattice with a self-similar distribution of hopping rates. We find that the time dependence of the mean-square displacement of both a tagged particle and the center of mass of the system present anomalous power laws modulated by logarithmic periodic oscillations. The anomalous exponent of a tagged particle is one half of the exponent of the center of mass, and always smaller than 1/4. Using heuristic arguments, the exponents and the periods of oscillation are analytically obtained and confirmed by Monte Carlo simulations.Comment: 12 pages, 6 figure

An updated catalog of OH-maser-emitting planetary nebulae

Aims. We studied the characteristics of planetary nebulae (PNe) that show both OH maser and radio continuum emission (hereafter OHPNe). These have been proposed to be very young PNe, and therefore, they could be key objects for understanding the formation and evolution of PNe. Methods. We consulted the literature searching for interferometric observations of radio continuum and OH masers toward evolved stars, including the information from several surveys. We also processed radio continuum and OH maser observations toward PNe in the Very Large Array data archive. The high positional accuracy provided by interferometric observations allow us to confirm or reject the association between OH maser and radio continuum emission. Results. We found a total of six PNe that present both OH maser and radio continuum emissions, as confirmed with radio interferometric observations. These are bona fide OHPNe. The confirmed OHPNe present a bipolar morphology in resolved images of their ionized emission at different wavelengths, suggesting that the OH maser emission in PNe is related to nonspherical mass-loss phenomena. The OH maser spectra in PNe present a clear asymmetry, tending to show blueshifted emission with respect to the systemic velocity. Their infrared colors suggest that most of these objects are very young PNe. OHPNe do not form a homogeneous group, and seem to represent a variety of different evolutionary stages. We suggest that OH masers pumped in the AGB phase may disappear during the post-AGB phase, but reappear once the source becomes a PN and its radio continuum emission is amplified by the OH molecules. Therefore, OH maser emission could last significantly longer than the previously assumed 1000 yr after the end of the AGB phase. This maser lifetime may be longer in PNe with more massive central stars, which ionize a larger amount of gas in the envelope.Comment: 16 pages, 5 figures, 4 tables. Accepted for publication by Astronomy & Astrophysic

Composition and Petrologic significance of Biotites and muscovites from the granitoids of the Boal-Los Ancares Metamorphic Belt (Westasturian Leonese Zone)

[Resumen] Las biotitas de los granitoides peralumínicos de la banda metamórfica Boal-Los Ancares se sitúan en el dominio de las biotitas s.s. con contenidos en Aliv que socilan entre 2.3 y 2.65 Yvalores de Fe/Fe + Mg entre 0.42 y 0.85. La variación composicional está controlada esencialmente por mecanismos de sustitución cati6nicaacoplada. La sustitución 3(R2+ti=2Alvi5+Ovi es más eficaz que la sustitución Al-Tschermak. La entraa3. de Ti en posiciones octaédricas está controlada por la sustitución 2Alvi=(Ti4+)vi +(R2+ Ji. La composición de las biotitas en base a sus contenidos en Al y Mg permite diferenciar tres grupos de granitoides, en concordancia con su mineralogía y composición de roca total. La variación composicional de la moscovita se produce principalmente a través de las sustituciones fengítica y paragonítica. El contenido máXimo en molécula cela~donítica es de 25 0A» Yel contenido máXimo en molécula paragonítica es de 12 %. Ni los caracteres texturales ni la composición química de este mineral constituyen un criterio definitivo en muchos casos para establecer su formación en el estadio magmático del sistema o bien en estadios posteriores. La composición de la moscovita en leucogranitos y aplitas sin biotita muestra notables particularidades con relación a la composición de este mineral en granitos de dos micas. Estas diferencias son manifiestas en las proporciones Ti:Mg:Na y Ti:Fe:Mg, las cuales muestran una buena correlación con algunos parámetros composicionales de roca total.[Abstract] Biotites from the peraluminous granitoids of the Boal-Los Ancares metamporphic band plot in the field ofbiotites s.s. with Aliv contents between 2.3 and 2.65 and Fe/Fe + Mg values ranging from 0.42 to 0.85. Compositional variation is basically controlled by coupled substitutional mechanisms. Substitution 3(R2+Yi =2Alvi+(Yi is more efficient than the Al-Tschermak substitution. Ti enters the octahedral sites via the 2Alvi = (Ti4+)vi+(R2+Yi substitution. The composition of biotites on the basis of Al and Mg contents pfudiscriminates three granitoid groups, this in agreement with their respective mineralogical composition and whole rock chemistry. Muscovite compositional variation is essentially due to the phengitic and paragonitic substitutions. The maxímum celaduníte content is 25 O/o and the maximum paragonite content is 12 %. Neither textural criteria nor chemical compositiori consitute unequivocal criteria for establishing the magmatic or submagmatic origin of the studied muscovites. Muscovite composition in biotite-free leucogranites and aplites shows distinctive features with respect to two-mica granites. This is particularly noticeable in the Ti:Mg:Na and Ti:Fe:Mg ratios, which correlate well with sorne whole rock compositional parameter

Petrología de la granodiorita de Peña Prieta (León, Santander, Palencia)

The granite autcrops of Peña Prieta situated on the harder of the Provinces of León, Santander and Palencia, are 1)etrologically studied in this work. This rock is a postectonic granodiorite with biotite and hornblende. The intense microtectonization in the mica is to he particularly noted in contrast with the remaining mineral components. The paragenetic relationship of the amphibol are also discussed

Water maser detections in southern candidates to post-AGB stars and Planetary Nebulae

We intended to study the incidence and characteristics of water masers in the envelopes of stars in the post-AGB and PN evolutionary stages. We have used the 64-m antenna in Parkes (Australia) to search for water maser emission at 22 GHz, towards a sample of 74 sources with IRAS colours characteristic of post-AGB stars and PNe, at declination $< -32 \deg$. In our sample, 39% of the sources are PNe or PNe candidates, and 50% are post-AGB stars or post-AGB candidates. We have detected four new water masers, all of them in optically obscured sources: three in PNe candidates (IRAS 12405-6219, IRAS 15103-5754, and IRAS 16333-4807); and one in a post-AGB candidate (IRAS 13500-6106). The PN candidate IRAS 15103-5754 has water fountain characteristics, and it could be the first PN of this class found. We confirm the tendency suggested in Paper I that the presence of water masers in the post-AGB phase is favoured in obscured sources with massive envelopes. We propose an evolutionary scenario for water masers in the post-AGB and PNe stages, in which ``water fountain'' masers could develop during post-AGB and early PN stages. Later PNe would show lower velocity maser emission, both along jets and close to the central objects, with only the central masers remaining in more evolved PNe.Comment: 11 pages, 5 figures. Accepted by Astronomy and Astrophysic

Análisis de los proyectos del sector agropecuario financiados por Colciencias durante el año 2010

Objetivo. Analizar los proyectos del sector agropecuario financiados por Colciencias durante el año 2010. Materiales y métodos. Se utilizó la base de datos de registro de proyectos correspondientes al Programa Nacional de Ciencia, Tecnología e Innovación Agropecuarias para identificar las propuestas presentadas, elegibles y financiadas de las convocatorias del año 2010. Los proyectos se clasificaron con base en la nomenclatura Internacional de la UNESCO para los campos de la ciencia y la tecnología. Se identificó la convocatoria, campos, disciplinas, rama productiva, entidades participantes, departamento de ejecución y montos financiados. Resultados. Durante el año 2010 Colciencias recibió un total de 4.725 propuestas para financiación, de éstas, 790 correspondieron al Programa Nacional de Ciencia, Tecnología e Innovación Agropecuaria. Las disciplinas de los proyectos financiados, fueron en su mayoría pertenecientes al subsector agrícola, seguido por el pecuario y el agroindustrial. Las universidades públicas fueron el tipo de entidad ejecutora al que se le financió un mayor número de proyectos. Los departamentos en los cuales se ejecutó la mayoría de las propuestas financiadas fueron Antioquia, Cundinamarca, Boyacá y Tolima. Conclusiones. El Programa Nacional de Ciencia Tecnología e Innovación Agropecuaria recibió el 16.7% del total de proyectos recibidos por Colciencias en sus convocatorias del año 2010. El mayor número de proyectos recibidos, elegibles y financiables fueron del subsector agrícola y estuvieron presentados y ejecutados por universidades públicas. La inversión total de Colciencias en proyectos del sector agropecuario fue de $32.923.594.000 con un aporte de contrapartida de$33.225.740.000