Protoplanetary disk lifetimes vs stellar mass and possible implications for giant planet populations

We study the dependence of protoplanetary disk evolution on stellar mass using a large sample of young stellar objects in nearby young star-forming regions. We update the protoplanetary disk fractions presented in our recent work (paper I of this series) derived for 22 nearby (< 500 pc) associations between 1 and 100 Myr. We use a subsample of 1 428 spectroscopically confirmed members to study the impact of stellar mass on protoplanetary disk evolution. We divide this sample into two stellar mass bins (2 M$_{\odot}$ boundary) and two age bins (3 Myr boundary), and use infrared excesses over the photospheric emission to classify objects in three groups: protoplanetary disks, evolved disks, and diskless. The homogeneous analysis and bias corrections allow for a statistically significant inter-comparison of the obtained results. We find robust statistical evidence of disk evolution dependence with stellar mass. Our results, combined with previous studies on disk evolution, confirm that protoplanetary disks evolve faster and/or earlier around high-mass (> 2 M$_{\odot}$) stars. We also find a roughly constant level of evolved disks throughout the whole age and stellar mass spectra. We conclude that protoplanetary disk evolution depends on stellar mass. Such a dependence could have important implications for gas giant planet formation and migration, and could contribute to explaining the apparent paucity of hot Jupiters around high-mass stars.Comment: Accepted for publication in A&A. 13 pages, 8 figures, 5 table

Tradición y novedad en el tratamiento de los tiempos verbales en diccionarios del español en el siglo XIX

El presente trabajo examina el tratamiento del ¿tiempo verbal¿ como accidente gramatical y la actualización de este concepto en un amplio conjunto de diccionarios del español publicados en el siglo XIX. El estudio y cotejo se realiza tanto en la macroestructura, como en la marcación especializada y su definición; de este modo se observa la dependencia del modelo gramatical ofrecido por las sucesivas ediciones del diccionario académico ‒modelo que, paulatinamente, y sobre todo, al final de la centuria, se va convirtiendo en normativo‒ y, además, el contraste que ofrece con los diccionarios no académicos del período, donde es posible encontrar en algunos casos esporádicos innovaciones destacadas que se vinculan de manera directa a las gramáticas españolas contemporáneas a ellos y muy próximas a los modelos franceses. This paper examines the treatment of tense as a grammatical accident and the updating of this concept in a wide range of Spanish dictionaries published in the nineteenth century. The study and comparison is performed both at the macrostructure and at the specialized marking, and its definition; thus we can observe the dependency of the grammar model offered by the successive editions of the dictionary academic model, ¿a model that, gradually, and especially at the end of the century, was becoming normative¿, as well as the contrast offered by the non-academic dictionaries of the period, where it is possible to find sporadically some outstanding innovations that are linked directly to their contemporary Spanish grammar books and very close to the French models

La F- inicial latina en los orígenes de la lengua española (I)

The first part of this study (I) deals with Latin's initial If! sound weakening to (h) and its subsequent loss in the language's initial stages. We assess the various explanations which have been proposed for this aspiration: a Latin dialectal feature, an internal evolution of the phonological system, a product ofthe Iberian-Basque substratum, and its relationship with Old Basque aspiration. Additionally, we analyse the first documentary evidence in the various Hispanic dialects from the IX to the XII century, bearing in mind that this phenomenon originally appeared in an area with close geographical links to Basque. With regard to spelling correspondences as evidence ofan ongoing phonetic change, we make a some general comments on the uses of writing which might reflect characteristics of speech, taking into account the special relationship between oral and written language in the medieval period

Ideología en el Diccionario Nacional (1846-47) de Ramón Joaquín Domínguez: la nomenclatura vergonzante

En este estudio se analiza una muestra de las voces sometidas a tabú presentes en el Diccionario Nacional (1846-47) de R. J. Domínguez. Se analizan sus técnicas lexicográficas en la presentación y tratamiento de estas voces, en contraste con el Diccionario de la RAE (1843) y con el Nuevo diccionario (1843) de V. Salvá. Se analiza la presencia de la ideología y la subjetividad del autor sobre este ámbito del léxico en relación con las restricciones sociales y las prácticas lexicográficas del siglo XIX

La articulación de los sonidos en la lexicografía del español (siglos XIX y XX)

En los artículos dedicados a las letras del alfabeto en la lexicografía del español aparecen, junto a otras informaciones de tipo enciclopédico, descripciones de la articulación de los sonidos y de su ortografía en una tradición que arranca del Tesoro de Covarrubias. Asimismo, para el siglo XVIII, desde una perspectiva ortográfica, se ha examinado la información fonética que aparece en el Diccionario de Autoridades o en el de Terreros (Martínez Alcalde 2010a) y, dentro de las obras académicas, el período comprendido entre el Diccionario de Autoridades (DA) y el Diccionario de la lengua castellana o (DRAE) de 1817 cuenta con el estudio de Pozuelo (1989), que establece con precisión el origen y fuentes del tratamiento fonético de las letras. Durante la primera mitad del siglo XIX, además, el diccionario es campo de ensayo de las innovaciones ortográficas que van adaptando la ortografía a la pronunciación. Estas innovaciones sólo quedarán reflejadas con posterioridad a ellos en las obras ortográficas de la Academia (Quilis Merín, 2008) en un contexto de polémicas en torno a las propuestas ortográficas filosóficas o fonetistas dentro y fuera de España, y a la oficialización de la ortografía académica con la publicación del Prontuario (1844) de la Academia. A este hecho se une la aparición de nuevo tipo de diccionario enciclopédico en el panorama español que se abre a la incorporación de un léxico más especializado. Hacia finales de la centuria, el desarrollo de la nueva ciencia del sonido, la fonética, en el ámbito europeo es una de las circunstancias que podrían matizar el análisis y valoración de estas entradas y su tratamiento lexicográfico. Nos proponemos observar el rumbo que toma la terminología fonética y la descripción articulatoria de las letras del alfabeto como representantes de los sonidos del habla que aparece en el encabezado de los artículos relativos a las letras desde el DRAE de 1817, tanto en los diccionarios académicos, como en una nómina de diccionarios no académicos formada por los generales de Taboada (1825), González Arnao (1828), Peñalver (1843), Labernia (1844), Salvá (1846), Castro y Rossi (1852), Marty Caballero (1884), Alemany (1917) y Pagés (1902-1931) y los diccionarios totalizadores, enciclopédicos o técnicos de Domínguez (1846-7), Gaspar y Roig (1853), Zerolo (1895), Toro (1901) y Rodríguez Navas (1918) de manera que, sin ser exhaustiva, la muestra pueda revelar las tendencias que presenta la lexicografía monolingüe del período hasta los primeros años del siglo X

Spectroscopic properties of Young Stellar Objects in the Lupus Molecular Clouds

The results of an optical spectroscopic survey of a sample of young stellar objects (YSOs) and pre-main sequence (PMS) stars in the Lupus Clouds are presented. 92 objects were observed with VLT/FLAMES. All of those objects show IR excess as discovered by the Spitzer Legacy Program "From Molecular Cores to Planet-Forming Disks" (c2d). After reduction, 54 spectra with good signal-to-noise ratio are spectrally classified. Effective temperatures and luminosities are derived for these objects, and used to construct H-R diagrams for the population. The sample consists mostly of M-type stars, with 10% K-type stars. Individual ages and masses are inferred for the objects according to theoretical evolutionary models. The mean population age is found to be between 3.6 and 4.4 Myr, depending on the model, while the mean mass is found to be ~0.3 M for either model. Together with literature data, the distribution of spectral types is found to be similar to that in Chamaeleon I and IC348. The H{\alpha} line in emission, found in 49% of the sample, is used to distinguish between classical and weak-line T Tauri stars. 56% of the objects show H{\alpha} in emission and are accreting T Tauri stars. Mass accretion rates between 10-8 and 10-11 M yr-1 are determined from the full width at 10% of the H{\alpha} peak intensity. These mass accretion rates are, within a large scatter, consistent with the Mac \propto M 2 relation found in the literature.Comment: 13 figures, 4 tables, Accepted for publication in MNRA

Herschel/PACS photometry of transiting-planet host stars with candidate warm debris disks

Dust in debris disks is produced by colliding or evaporating planetesimals, remnants of the planet formation process. Warm dust disks, known by their emission at < 24 micron, are rare (4% of FGK main sequence stars) and especially interesting because they trace material in the region likely to host terrestrial planets, where the dust has a very short dynamical lifetime. Statistical analyses of the source counts of excesses as found with the mid-IR Wide Field Infrared Survey Explorer (WISE) suggest that warm-dust candidates found for the Kepler transiting-planet host-star candidates can be explained by extragalactic or galactic background emission aligned by chance with the target stars. These statistical analyses do not exclude the possibility that a given WISE excess could be due to a transient dust population associated with the target. Here we report Herschel/PACS 100 and 160 micron follow-up observations of a sample of Kepler and non-Kepler transiting-planet candidates' host stars, with candidate WISE warm debris disks, aimed at detecting a possible cold debris disk in any of them. No clear detections were found in any one of the objects at either wavelength. Our upper limits confirm that most objects in the sample do not have a massive debris disk like that in beta Pic. We also show that the planet-hosting star WASP-33 does not have a debris disk comparable to the one around eta Crv. Although the data cannot be used to rule out rare warm disks around the Kepler planet-hosting candidates, the lack of detections and the characteristics of neighboring emission found at far-IR wavelengths support an earlier result suggesting that most of the WISE-selected IR excesses around Kepler candidate host stars are likely due to either chance alignment with background IR-bright galaxies and/or to interstellar emission.Comment: 8 pages, 3 figures, accepted for publication at Astronomy & Astrophysics on 4 August 201

A deep optical/near-infrared catalog of Serpens

We present a deep optical/near-infrared imaging survey of the Serpens molecular cloud. This survey constitutes the complementary optical data to the Spitzer "Core To Disk" (c2d) Legacy survey in this cloud. The survey was conducted using the Wide Field Camera at the Isaac Newton Telescope. About 0.96 square degrees were imaged in the R and Z filters, covering the entire region where most of the young stellar objects identified by the c2d survey are located. 26524 point-like sources were detected in both R and Z bands down to R=24.5 mag and Z=23 mag with a signal-to-noise ratio better than 3. The 95% completeness limit of our catalog corresponds to 0.04 solar masses for members of the Serpens star forming region (age 2 Myr and distance 260 pc) in the absence of extinction. Adopting the typical extinction of the observed area (Av=7 mag), we estimate a 95% completeness level down to 0.1 solar masses. The astrometric accuracy of our catalog is 0.4 arcsec with respect to the 2MASS catalog. Our final catalog contains J2000 celestial coordinates, magnitudes in the R and Z bands calibrated to the SDSS photometric system and, where possible, JHK magnitudes from 2MASS for sources in 0.96 square degrees in the direction of Serpens. This data product has been already used within the frame of the c2d Spitzer Legacy Project analysis in Serpens to study the star/disk formation and evolution in this cloud; here we use it to obtain new indications of the disk-less population in Serpens.Comment: 7 page, 5 figure