48 research outputs found

    A feature-rich transmission spectrum for WASP-127b

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    WASP-127b is one of the lowest density planets discovered to date. With a sub-Saturn mass (Mp=0.18±0.02MJM_{\rm p}=0.18 \pm 0.02 M_J) and super-Jupiter radius (Rp=1.37±0.04RJR_{\rm p}= 1.37 \pm 0.04 R_J), it orbits a bright G5 star, which is about to leave the main-sequence. We aim to explore WASP-127b's atmosphere in order to retrieve its main atmospheric components, and to find hints for its intriguing inflation and evolutionary history. We used the ALFOSC spectrograph at the NOT telescope to observe a low resolution (R330R\sim330, seeing limited) long-slit spectroscopic time series during a planetary transit, and present here the first transmission spectrum for WASP-127b. We find the presence of a strong Rayleigh slope at blue wavelengths and a hint of Na absorption, although the quality of the data does not allow us to claim a detection. At redder wavelengths the absorption features of TiO and VO are the best explanation to fit the data. Although higher signal-to-noise ratio observations are needed to conclusively confirm the absorption features, WASP-127b seems to posses a cloud-free atmosphere and is one of the best targets to perform further characterization studies in the near future.Comment: Accepted for Publication A&A Letters, May 22nd, 201

    Multicolour photometry for exoplanet candidate validation

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    Context. The TESS and PLATO missions are expected to find vast numbers of new transiting planet candidates. However, only a fraction of these candidates will be legitimate planets, and the candidate validation will require a significant amount of follow-up resources. Radial velocity follow-up can be carried out only for the most promising candidates around bright, slowly rotating, stars. Thus, before devoting RV resources to candidates, they need to be vetted using cheaper methods, and, in the cases for which an RV confirmation is not feasible, the candidate's true nature needs to be determined based on these alternative methods alone. Aims. We study the applicability of multicolour transit photometry in the validation of transiting planet candidates when the candidate signal arises from a real astrophysical source. We seek to answer how securely can we estimate the true uncontaminated star-planet radius ratio when the light curve may contain contamination from unresolved light sources inside the photometry aperture when combining multicolour transit observations with a physics-based contamination model. Methods. The study is based on simulations and ground-based transit observations. The analyses are carried out with a contamination model integrated into the PyTransit v2 transit modelling package, and the observations are carried out with the MuSCAT2 multicolour imager installed in the 1.5 m TCS in the Teide Observatory. Results. We show that multicolour transit photometry can be used to estimate the amount of flux contamination and the true radius ratio. Combining the true radius ratio with an estimate for the stellar radius yields the true absolute radius of the transiting object, which is a valuable quantity in statistical candidate validation, and enough in itself to validate a candidate whose radius falls below the theoretical lower limit for a brown dwarf.Comment: Accepted to A&

    Surface and Temporal Biosignatures

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    Recent discoveries of potentially habitable exoplanets have ignited the prospect of spectroscopic investigations of exoplanet surfaces and atmospheres for signs of life. This chapter provides an overview of potential surface and temporal exoplanet biosignatures, reviewing Earth analogues and proposed applications based on observations and models. The vegetation red-edge (VRE) remains the most well-studied surface biosignature. Extensions of the VRE, spectral "edges" produced in part by photosynthetic or nonphotosynthetic pigments, may likewise present potential evidence of life. Polarization signatures have the capacity to discriminate between biotic and abiotic "edge" features in the face of false positives from band-gap generating material. Temporal biosignatures -- modulations in measurable quantities such as gas abundances (e.g., CO2), surface features, or emission of light (e.g., fluorescence, bioluminescence) that can be directly linked to the actions of a biosphere -- are in general less well studied than surface or gaseous biosignatures. However, remote observations of Earth's biosphere nonetheless provide proofs of concept for these techniques and are reviewed here. Surface and temporal biosignatures provide complementary information to gaseous biosignatures, and while likely more challenging to observe, would contribute information inaccessible from study of the time-averaged atmospheric composition alone.Comment: 26 pages, 9 figures, review to appear in Handbook of Exoplanets. Fixed figure conversion error

    Perfil de pacientes hematológicos atendidos en un servicio de urgencias hospitalario

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    Poster [PC-355] Introducción: Durante los últimos años existe un aumento progresivo en la demanda de asistencia en los servicios de urgencias hospitalarios (SUH), tanto generales como pediátricos. Los pacientes hematológicos presentan numerosos episodios clínicos que precisan valoración clínica urgente y dada la facilidad de acceso a los SUH emplean este medio. Métodos: Estudio descriptivo observacional de las urgencias en pacientes con patología hematológica atendidas en el Servicio de Urgencias del Hospital Universitario Miguel Servet de Zaragoza (Hospital de tercer nivel). Periodo de estudio (Enero 2017-Diciembre 2017). Criterios de inclusión: Paciente: s con diagnóstico hematológico según la clasificación CIE-9 en el informe de alta de urgencias. Grupo de pacientes adultos (> 14 años): atendidos en el Hospital General, y grupo de pacientes pediátricos (< 14 años): atendidos en el Hospital Infantil. Variables analizadas: edad, sexo, grupo de patología y nivel de triaje. Datos recogidos a través del registro derivado de la Base de Datos generada por el aplicativo informático “Puesto Clínico Hospitalario de Urgencias”, que da soporte a la actividad asistencial de los servicios de urgencias hospitalarios de Aragón. Se obtuvo autorización correspondiente del centro y del SUH para el acceso a los datos informáticos. Resultados: Muestra total de 2193 pacientes: 1928 en el grupo de adultos y 265 en el grupo pediátrico. En el grupo de adultos la edad media de consulta en SUH fue de 71, 4 años (DE: 18.10), siendo el subgrupo de 81-90 años el que más frecuentemente acude (31.74%). En la población infantil la edad media de consulta fue de 6, 39 años (DE: 4.54), siendo entre los 0-2 años la edad que más frecuenta Urgencias (19.62%). Respecto a la distribución según sexo, el 55% de las consultas son realizadas por mujeres y el 45% por hombres. Sin embargo, en la población infantil el 52% de las consultas son realizadas por niños y el 48% por niñas. En el análisis según grupo de enfermedad: el grupo pediátrico consulta más frecuentemente por enfermedades de hemostasia (47.17%), mientras que los adultos consultan más por enfermedades de serie roja (61.28%). En ambos grupos, las consultas realizadas en Urgencias son de gran complejidad con una prioridad elevada de asistencia. El 93% de la patología en adultos y el 71% de la patología infantil hematológica es triada con niveles I-III de urgencia y tiempos asistenciales reducidos. Conclusiones: El comportamiento de las enfermedades hematológicas varía en función de la edad, el sexo y el tipo de enfermedad. La patología hematológica tiene un gran impacto dentro de los servicios de urgencias hospitalarios, dado que estos pacientes presentan un perfil complejo que requerirá diagnóstico y tratamiento rápido por la gravedad del tipo de complicaciones que asocian. En consonancia con la población envejecida, los pacientes que más demandan la atención en Urgencias y de forma repetida, son adultos muy mayores (81-90 años) pudiéndose plantear circuitos de asistencia urgente diferentes para estos pacientes

    Greening of the brown-dwarf desert EPIC 212036875b: a 51 M-J object in a 5-day orbit around an F7V star

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    Context. Although more than 2000 brown dwarfs have been detected to date, mainly from direct imaging, their characterisation is difficult due to their faintness and model-dependent results. In the case of transiting brown dwarfs, however, it is possible to make direct high-precision observations. Aims. Our aim is to investigate the nature and formation of brown dwarfs by adding a new well-characterised object, in terms of its mass, radius and bulk density, to the currently small sample of less than 20 transiting brown dwarfs. Methods. One brown dwarf candidate was found by the KESPRINT consortium when searching for exoplanets in the K2 space mission Campaign 16 field. We combined the K2 photometric data with a series of multicolour photometric observations, imaging, and radial velocity measurements to rule out false positive scenarios and to determine the fundamental properties of the system. Results. We report the discovery and characterisation of a transiting brown dwarf in a 5.17-day eccentric orbit around the slightly evolved F7V star EPIC 212036875. We find a stellar mass of 1.15 +/- 0.08 M-circle dot, a stellar radius of 1.41 +/- 0.05 R-circle dot, and an age of 5.1 +/- 0.9 Gyr. The mass and radius of the companion brown dwarf are 51 +/- 2 M-J and 0.83 +/- 0.03 R-J, respectively, corresponding to a mean density of 108(-13)(+15) g cm(-3). Conclusions. EPIC 212036875 b is a rare object that resides in the brown-dwarf desert. In the mass-density diagram for planets, brown dwarfs, and stars, we find that all giant planets and brown dwarfs follow the same trend from similar to 0.3 M-J to the turn-over to hydrogen burning stars at similar to 73 M-J. EPIC 212036875 b falls close to the theoretical model for mature H/He dominated objects in this diagram as determined by interior structure models. We argue that EPIC 212036875 b formed via gravitational disc instabilities in the outer part of the disc, followed by a quick migration. Orbital tidal circularisation may have started early in its history for a brief period when the brown dwarf\u27s radius was larger. The lack of spin-orbit synchronisation points to a weak stellar dissipation parameter (Q(star)\u27 greater than or similar to 10(8)), which implies a circularisation timescale of greater than or similar to 23 Gyr, or suggests an interaction between the magnetic and tidal forces of the star and the brown dwarf
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