112 research outputs found

    Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk

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    Elias 2-27 is a young star that hosts an extended, bright and inclined disk of dust and gas. The inclination and extreme flaring of the disk make Elias 2-27 an ideal target to study the vertical distribution of molecules, particularly CN. We directly trace the emission of CN in Elias 2-27 and compare it to previously published CO isotopologue data. CN N=32N = 3-2 emission is analyzed in two different transitions J=7/25/2J = 7/2 - 5/2 and J=5/23/2J = 5/2 - 3/2, for which we detect two hyperfine group transitions. The vertical location of CN emission is traced directly from the channel maps, following geometrical methods that have been previously used to analyze the CO emission of Elias 2-27. Analytical models are used to parametrize the vertical profile of each molecule and study the extent of each tracer, additionally we compute radial profiles of column density and optical depth. We show that the vertical location of CN and CO isotopologues in Elias 2-27 is layered and consistent with predictions from thermochemical models. A north/south asymmetry in the radial extent of CN is detected and we find that the CN emission is mostly optically thin and constrained vertically to a thin slab at z/rz/r \sim0.5. A column density of 1014^{14}\,cm2^{-2} is measured in the inner disk which for the north side decreases to 1012^{12}\,cm2^{-2} and for the south side to 1013^{13}\,cm2^{-2} in the outer regions. In Elias 2-27, CN traces a vertically elevated region above the midplane, very similar to that traced by 12^{12}CO. The inferred CN properties are consistent with thermo-chemical disk models, in which CN formation is initiated by the reaction of N with UV-pumped H2_2. The observed north/south asymmetry may be caused by either ongoing infall or by a warped inner disk. This study highlights the importance of tracing the vertical location of various molecules to constrain the disk physical conditions.Comment: Accepted for publication in A&A, 19 pages, 14 figure

    Gas temperature structure across transition disk cavities

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    [Abridged] Most disks observed at high angular resolution show substructures. Knowledge about the gas surface density and temperature is essential to understand these. The aim of this work is to constrain the gas temperature and surface density in two transition disks: LkCa15 and HD 169142. We use new ALMA observations of the 13^{13}CO J=65J=6-5 transition together with archival J=21J=2-1 data of 12^{12}CO, 13^{13}CO and C18^{18}O to observationally constrain the gas temperature and surface density. Furthermore, we use the thermochemical code DALI to model the temperature and density structure of a typical transition disk. The 65/216-5/2-1 line ratio in LkCa15 constrains the gas temperature in the emitting layers inside the dust cavity to be up to 65 K, warmer than in the outer disk at 20-30 K. For the HD 169142, the peak brightness temperature constrains the gas in the dust cavity of HD 169142 to be 170 K, whereas that in the outer disk is only 100 K. Models also show that a more luminous central star, a lower abundance of PAHs and the absence of a dusty inner disk increase the temperature of the emitting layers and hence the line ratio in the gas cavity. The gas column density in the LkCa15 dust cavity drops by a factor >2 compared to the outer disk, with an additional drop of an order of magnitude inside the gas cavity at 10 AU. In the case of HD 169142, the gas column density drops by a factor of 200-500 inside the gas cavity, which could be due to a massive companion of several MJ_{\mathrm{J}}. The broad dust-depleted gas region from 10-68 AU for LkCa15 may imply several lower mass planets. This work demonstrates that knowledge of the gas temperature is important to determine the gas surface density and thus whether planets, and if so what kind of planets, are the most likely carving the dust cavities.Comment: Accepted for publication in Astronomy and astrophysic

    The Al Hoceima 2016 seismic series. Strain partitioning and interaction of structures on a diffuse plate boundary

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    El terremoto principal de la serie sísmica tuvo lugar el 25 de enero de 2016, con una magitud Mw 6.3, que fue precedido por un premonitorio de magnitud Mw 5.1 el día 21 de enero. Hemos utilizado 41 mecanismos focales para analizar las características sismotectónicas y estructurales de la serie. Para agrupar los mecanismo focales hemos utilizado un algoritmo de agrupamiento jerárquico espacial y por el tipo de rotura del mecanismo. De cada agrupación hemos obtenido el mecanismo focal medio y lo hemos asociado a una estructura o familia de estructuras. Hemos comprobado la compatibilidad mecánica de estas estructuras mediante transferencia de esfuerzos de Coulomb. El evento principal de la serie se produjo en la Falla de Al Idrisi intersectando la cresta de Alborán. Este evento disparó réplicas y series independientes en fallas de desgarre asociadas al sistema de Falla de Al Idrisi hacia el sur, pero también en fallas inversas asociadas al levantamiento de la Cresta de Alborán hacia el este; produciendose una partición de la deformación entre ambos tipos de estructuras interaccionando por transferencia de esfuerzos.The mainshock of seismic series took place on January 25, 2016, with a Mw 6.3 magnitude, which was preceded by a premonitory of magnitude Mw 5.1 on 21 January. We have used 41 focal mechanisms to analyze the seismotectonics and the structural characteristics of the series. To cluster the focal mechanisms we used a hierarchical clustering algorithm using the spatial distribution of the events and also the type of rupture mechanism. For each cluster we have obtained the average focal mechanism and have been associated with a structure or family of structures. We have tested the mechanical compatibility of these structures by Coulomb stress transfer modelling. The mainshock of the series occurred in the Al Idrisi Fault intersecting the Alboran Ridge. This event triggered aftershocks and independent series in strike-slip faults associated with the Al Idrisi Fault System towards the south, but also in reverse faults associated with the lifting of the Alboran Ridge eastward; producing a strain partitioning between both types of structures interacting by stress transfer.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEMinisterio de Economía y Competitividad (MINECO)pu

    Characterization of Color Production in Xalla´s Palace Complex, Teotihuacan

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    A multi-analytical approach was used to characterize color remains from Xalla, a Teotihuacan palace complex (project Teotihuacan, Elite and Government. Excavations in Xalla led by Linda R. Manzanilla). Color samples were obtained from polished lithic instruments and pigment ores. Those samples were analyzed combining microscopic and spectroscopic techniques. Our results coincide with previous studies in Teotihuacan, with the chromatic palette displaying a predominance of iron oxides such as hematite, yellow ochre and natural earths, as well as malachite, celadonite and glauconite. We have enlarged the corpus of raw materials with the characterization of jarosite and bone white and mica as aggregate. The identification of raw materials crossed with functional analysis of polished lithic artefacts suggests a production and application process for the pigmenting materials that were divided in four phases, from the crushing of the raw material to the application and finishing of the painted surfaces

    NFAT5 Is Activated by Hypoxia: Role in Ischemia and Reperfusion in the Rat Kidney

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    The current hypothesis postulates that NFAT5 activation in the kidney's inner medulla is due to hypertonicity, resulting in cell protection. Additionally, the renal medulla is hypoxic (10–18 mmHg); however there is no information about the effect of hypoxia on NFAT5. Using in vivo and in vitro models, we evaluated the effect of reducing the partial pressure of oxygen (PO2) on NFAT5 activity. We found that 1) Anoxia increased NFAT5 expression and nuclear translocation in primary cultures of IMCD cells from rat kidney. 2) Anoxia increased transcriptional activity and nuclear translocation of NFAT5 in HEK293 cells. 3) The dose-response curve demonstrated that HIF-1α peaked at 2.5% and NFAT5 at 1% of O2. 4) At 2.5% of O2, the time-course curve of hypoxia demonstrated earlier induction of HIF-1α gene expression than NFAT5. 5) siRNA knockdown of NFAT5 increased the hypoxia-induced cell death. 6) siRNA knockdown of HIF-1α did not affect the NFAT5 induction by hypoxia. Additionally, HIF-1α was still induced by hypoxia even when NFAT5 was knocked down. 7) NFAT5 and HIF-1α expression were increased in kidney (cortex and medulla) from rats subjected to an experimental model of ischemia and reperfusion (I/R). 7) Experimental I/R increased the NFAT5-target gene aldose reductase (AR). 8) NFAT5 activators (ATM and PI3K) were induced in vitro (HEK293 cells) and in vivo (I/R kidneys) with the same timing of NFAT5. 8) Wortmannin, which inhibits ATM and PI3K, reduces hypoxia-induced NFAT5 transcriptional activation in HEK293 cells. These results demonstrate for the first time that NFAT5 is induced by hypoxia and could be a protective factor against ischemic damage

    Broad-band high-resolution rotational spectroscopy for laboratory astrophysics

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    We present a new experimental set-up devoted to the study of gas phase molecules and processes using broad-band high spectral resolution rotational spectroscopy. A reactor chamber is equipped with radio receivers similar to those used by radio astronomers to search for molecular emission in space. The whole range of the Q (31.5-50 GHz) and W bands (72-116.5 GHz) is available for rotational spectroscopy observations. The receivers are equipped with 16 × 2.5 GHz fast Fourier transform spectrometers with a spectral resolution of 38.14 kHz allowing the simultaneous observation of the complete Q band and one-third of the W band. The whole W band can be observed in three settings in which the Q band is always observed. Species such as CH3CN, OCS, and SO2 are detected, together with many of their isotopologues and vibrationally excited states, in very short observing times. The system permits automatic overnight observations, and integration times as long as 2.4 × 105 s have been reached. The chamber is equipped with a radiofrequency source to produce cold plasmas, and with four ultraviolet lamps to study photochemical processes. Plasmas of CH4, N2, CH3CN, NH3, O2, and H2, among other species, have been generated and the molecular products easily identified by the rotational spectrum, and via mass spectrometry and optical spectroscopy. Finally, the rotational spectrum of the lowest energy conformer of CH3CH2NHCHO (N-ethylformamide), a molecule previously characterized in microwave rotational spectroscopy, has been measured up to 116.5 GHz, allowing the accurate determination of its rotational and distortion constants and its search in space.We thank the European Research Council for funding support under Synergy Grant ERC-2013-SyG, G.A. 610256 (NANOCOSMOS). IT, VJH, and JLD acknowledge additional partial support from the Spanish State Research Agency (AEI) through grant FIS2016-77726-C3-1-P. JAMG, LM, and GS acknowledge additional partial support from the Spanish State Research Agency (AEI) through grant MAT2017-85089-C2-1R. We thank David López Romero for his help during the process of installation, commissioning, and cleaning of the chamber. We would like to thank Kremena Makasheva for the useful comments and suggestions during the experiments with Hexamethyldisiloxane. We would also like to thank Rosa Lebrón, Jesús Quintanilla, and Cristina Soria for providing us with the sample of N-ethylformamide. Sandra I. Ramírez acknowledges support from the FONCICYT under grant number 291842. Celina Bermúdez thanks the Spanish Ministerio de Ciencia Innovación y Universidades for the Juan de la Cierva grant FJCI-2016-27983
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