45 research outputs found
Espectros en el infrarrojo medio de discos de escombros
Se presentan espectros en el infrarrojo medio de 3 estrellas (edades de 107 – 109 a˜nos) asociadas con discos de escombros. Los espectros se compararon con perfiles de absorci´on de compuestos de tipo amorfo y cristalino. La presencia de bandas de absorci´on no puede explicarse considerando s´olo compuestos del tipo amorfo sugiriendo la existencia de compuestos del tipo cristalino. Adem´as, las part´ıculas de polvo tendr´ıan tama˜nos > 1.5 µm. Esto evidenciar´ıa que el material de los discos de escombros se encuentra en un estado evolutivo m´as avanzado que en los discos en estrellas de tipo T - Tauri (∼ 106 a˜nos) o del medio interestelar, poblados principalmente por part´ıculas de polvo con tama˜nos de ∼ 0.1 µm constituidas por silicatos del tipo amorfo.In this contribution we report mid-infrared spectra of 3 stars (ages 107 – 109 yrs) with known debris disks. These spectra are compared with the absorption profiles of crystalline and amorphous silicates. The presence of absorption bands can be explained by considering the existence of amorphous compounds together with those of the crystalline type. In addition, dust particles may have typical sizes > 1.5 µm. This would indicate that the material in the debris disks is in a more advanced evolutionary state than in disks around T - Tauri stars (∼ 106 years) or in the interstellar medium, populated by dust particles with sizes ∼ 0.1 µm consisting of amorphous silicates.Fil: García, Luciano Héctor. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Mercedes Nieves. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Modeling of debris disks in single and binary stars
Infrared space observatories such as Spitzer and Herschel have allowed the detection of likely analogs to the Kuiper Belt in single as well as binary systems. The aim of this work is to characterize debris disks in single and binary stars and to identify features shared by the disks in both types of systems, as well as possible differences. We compiled a sample of 25 single and 14 binary stars (ages > 100 Myr) and flux measurements at lambda > 100 microns and evidence of infrared excesses attributed to the presence of debris disks. Then, we constructed and modeled the observed spectral energy distributions (SEDs), and compared the parameters of the disks of both samples. Both types of disks are relatively free of dust in the inner region ( 100 × 106 años) con flujos observados para λ > 100 µm y evidencia de excesos en emisión en el infrarrojo atribuidos a la presencia de disco. Luego, se construyeron y modelaron las distribuciones espectrales de energía (SEDs), y se compararon los parámetros obtenidos para los discos de ambas muestras. En general, los discos tienen una región interna (< 3-5 UA), relativamente libre de polvo y se extenderían más allá de 100 UA. No se encontraron diferencias significativas en las distribuciones de masa y de tamaño de las partículas de polvo de ambas muestras.Fil: García, Luciano Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Gomez, Mercedes Nieves. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentin
High-contrast imaging of HD 29992 and HD 196385 with the Gemini Planet Imager
Based on high contrast images obtained with the Gemini Planet Imager (GPI), we report the discovery of two point-like sources at angular separations of ∼ 0.1800 and ∼ 0.8000 from the stars HD 29992 and HD 196385. A combined analysis of the new GPI observations and images from the literature indicates that the source close to HD 29992 could be a companion to the star. Concerning HD 196385, the small number of contaminants (∼ 0.5) suggests that the detected source may be gravitationally bound to the star. For both systems, we discarded the presence of other potential companions with > 75 MJup at ∼ 0.3−1.3 00. From stellar model atmospheres and low-resolution GPI spectra, we derive masses of ∼ 0.2 - 0.3 M for these sources. Using a Markov-chain Monte Carlo approach, we performed a joint fit of the new astrometry measurements and published radial velocity data to characterize the possible orbits. For HD 196385B, the median dynamic mass is in agreement with that derived from model atmospheres, whilst for HD 29992B, the orbital fit favors masses close to the brown dwarf regime(∼ 0.08 M). HD 29992 and HD 196385 might be two new binary systems with M-type stellar companions. However, new high angular resolution images would help to definitively confirm whether the detected sources are gravitationally bound to their respective stars, and permittighter constraints on the orbital parameters of both systems.Fil: García, Luciano Héctor. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Petrucci, Romina Paola. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Jofre, Jorge Emiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; ArgentinaFil: Gomez, Mercedes Nieves. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentin
Ejercicio aeróbico en las medidas antropométricas en mujeres posparto en el covid-19 / Exercício aeróbico nas medidas antropométricas em mulheres pós-parto na covid-19
La gestación produce cambios antropométricos marcados, por lo que el ejercicio aeróbico puede reducir los valores de masa corporal en mujeres posparto en el contexto de confinamiento y aislamiento social por la pandemia COVID-19. El estudio aplicó un programa de ejercicio aeróbico durante 16 semanas, en una muestra de 10 mujeres voluntarias posparto con edad promedio de 29,8 ± 8,7 años. Los datos antropométricos fueron evaluados estimados con una cinta métrica y balanza electrónica. Los resultados al comparar el pre-test del pos-test se encontraron, diferencias significativas en la reducción de las medidas antropométricas: IMC, peso, perímetro del cuello, hombros, pectoral, brazos y cintura, a excepción del perímetro de los glúteos y cuádriceps en las cuales encontraremos mínimas diferencias. El ejercicio aeróbicos realizado por mujeres posparto a moderada intensidad y prolongada duración, genera reducción significativa en las medidas antropométricas mejorando la imagen corporal y autoestima de las mujeres
Atmospheric deposition of inorganic nitrogen in Spanish holm oak forests measured with ion-exchange resins and conventional collectors
Atmospheric nitrogen deposition is one of the main threats for biodiversity and ecosystem functioning. Measurement techniques like ion-exchange resin collectors (IECs), which are less expensive and timeconsuming than conventional methods, are gaining relevance in the study of atmospheric deposition and are recommended to expand monitoring networks. In the present work, bulk and throughfall deposition of inorganic nitrogen were monitored in three different holm oak forests in Spain during two years. The results obtained with IECs were contrasted with a conventional technique using bottle collectors and with a literature review of similar studies. The performance of IECs in comparison with the conventional method was good for measuring bulk deposition of nitrate and acceptable for ammonium and total dissolved inorganic nitrogen. Mean annual bulk deposition of inorganic nitrogen ranged 3.09 e5.43 kg N ha1 according to IEC methodology, and 2.42e6.83 kg N ha1 y1 using the conventional method. Intra-annual variability of the net throughfall deposition of nitrogen measured with the conventional method revealed the existence of input pulses of nitrogen into the forest soil after dry periods, presumably originated from the washing of dry deposition accumulated in the canopy. Important methodological recommendations on the IEC method and discussed, compiled and summarized
Quantitative study on nitrogen deposition and canopy retention in Mediterranean evergreen forests
Altres ajuts: This research was also funded by the project from Autonomous Government of Madrid AGRISOST-CM (P2013/ABI-2717). CIEMAT work in this study was partially supported by an agreement between the Spanish Ministry of Agriculture, Food and Environment and CIEMAT on Critical loads and levels. The utilization of Tres Cantos monitoring site was possible thanks to an agreement between CIEMAT and Ayuntamiento de Madrid.To assess the impact of nitrogen (N) pollutants on forest ecosystems, the role of the interactions in the canopy needs to be understood. A great number of studies have addressed this issue in heavily N-polluted regions in north and central Europe. Much less information is available for the Iberian Peninsula, and yet this region is home to mountain forests and alpine grasslands that may be at risk due to excessive N deposition. To establish the basis for ecology-based policies, there is a need to better understand the forest response to this atmospheric impact. To fill this gap, in this study, we measured N deposition (as bulk, wet, and throughfall fluxes of dissolved inorganic nitrogen) and air N gas concentrations from 2011 to 2013 at four Spanish holm oak (Quercus ilex) forests located in different pollution environments. One site was in an area of intensive agriculture, two sites were influenced by big cities (Madrid and Barcelona, respectively), and one site was in a rural mountain environment 40 km north of Barcelona. Wet deposition ranged between 0.54 and 3.8 kg N ha⁻¹ year⁻¹ for ammonium (NH₄⁺)-N and between 0.65 and 2.1 kg N h⁻¹ year⁻¹ for nitrate (NO₃⁻)-N, with the lowest deposition at the Madrid site for both components. Dry deposition was evaluated with three different approaches: (1) a canopy budget model based in throughfall measurements, (2) a branch washing method, and (3) inferential calculations. Taking the average dry deposition from these methods, dry deposition represented 51-67% (reduced N) and 72-75% (oxidized N) of total N deposition. Canopies retained both NH₄⁺-N and NO₃⁻N, with a higher retention at the agricultural and rural sites (50-60%) than at sites located close to big cities (20-35%, though more uncertainty was found for the site near Madrid), thereby highlighting the role of the forest canopy in processing N pollutant emissions
Bases per a la renovació de l’espai comunicatiu valencià i la restitució del servei públic de radiotelevisió. Informe de la Comissió d’Experts en comunicació de les universitats valencianes (CECUV)
Informe encarregat pel Fòrum Social de l'Audiovisual Valenci
Bases para la renovación del espacio comunicativo valenciano y la restitución del servicio público de radiotelevisión. Informe de la Comisión de Expertos en Comunicación de las Universidades Valencianas (CECUV) (traducción al castellano)
Traducción al castellano del informe: Bases per a la renovació de l’espai comunicatiu valencià i la restitució del servei públic de radiotelevisió. Informe de la Comissió d’Experts en comunicació de les universitats valencianes (CECUV
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected