224 research outputs found

    Asteroseismology of the Hyades red giant and planet host epsilon Tauri

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    Asteroseismic analysis of solar-like stars allows us to determine physical parameters such as stellar mass, with a higher precision compared to most other methods. Even in a well-studied cluster such as the Hyades, the masses of the red giant stars are not well known, and previous mass estimates are based on model calculations (isochrones). The four known red giants in the Hyades are assumed to be clump (core-helium-burning) stars based on their positions in colour-magnitude diagrams, however asteroseismology offers an opportunity to test this assumption. Using asteroseismic techniques combined with other methods, we aim to derive physical parameters and the evolutionary stage for the planet hosting star epsilon Tau, which is one of the four red giants located in the Hyades. We analysed time-series data from both ground and space to perform the asteroseismic analysis. By combining high signal-to-noise (S/N) radial-velocity data from the ground-based SONG network with continuous space-based data from the revised Kepler mission K2, we derive and characterize 27 individual oscillation modes for epsilon Tau, along with global oscillation parameters such as the large frequency separation and the ratio between the amplitude of the oscillations measured in radial velocity and intensity as a function of frequency. The latter has been measured previously for only two stars, the Sun and Procyon. Combining the seismic analysis with interferometric and spectroscopic measurements, we derive physical parameters for epsilon Tau, and discuss its evolutionary status.Comment: 13 pages, 13 figures, 4 tables, accepted for publication in Astronomy & Astrophysic

    Health-related quality of life in patients with newly diagnosed inflammatory bowel disease: an observational prospective cohort study (IBSEN III)

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    Purpose This unselected, population-based cohort study aimed to determine the level of health-related quality of life (HRQoL) in patients with Crohn’s disease (CD) and ulcerative colitis (UC) at the time of diagnosis compared with a reference population and identify the demographic factors, psychosocial measures, and disease activity markers associated with HRQoL. Methods Adult patients newly diagnosed with CD or UC were prospectively enrolled. HRQoL was measured using the Short Form 36 (SF-36) and Norwegian Inflammatory Bowel Disease Questionnaires. Clinical significance was assessed using Cohen’s d effect size and further compared with a Norwegian reference population. Associations between HRQoL and symptom scores, demographic factors, psychosocial measures, and disease activity markers were analyzed. Results Compared with the Norwegian reference population, patients with CD and UC reported significantly lower scores in all SF-36 dimensions, except for physical functioning. Cohen’s d effect sizes for men and women in all SF-36 dimensions were at least moderate, except for bodily pain and emotional role for men with UC and physical functioning for both sexes and diagnoses. In the multivariate regression analysis, depression subscale scores ≥ 8 on the Hospital Anxiety and Depression Scale, substantial fatigue, and high symptom scores were associated with reduced HRQoL. Conclusion Patients newly diagnosed with CD and UC reported statistically and clinically significantly lower scores in seven of the eight SF-36 dimensions than the reference population. Symptoms of depression, fatigue, and elevated symptom scores were associated with poorer HRQoL.publishedVersio

    The Transiting System GJ1214: High-Precision Defocused Transit Observations and a Search for Evidence of Transit Timing Variation

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    Aims: We present 11 high-precision photometric transit observations of the transiting super-Earth planet GJ1214b. Combining these data with observations from other authors, we investigate the ephemeris for possible signs of transit timing variations (TTVs) using a Bayesian approach. Methods: The observations were obtained using telescope-defocusing techniques, and achieve a high precision with random errors in the photometry as low as 1mmag per point. To investigate the possibility of TTVs in the light curve, we calculate the overall probability of a TTV signal using Bayesian methods. Results: The observations are used to determine the photometric parameters and the physical properties of the GJ1214 system. Our results are in good agreement with published values. Individual times of mid-transit are measured with uncertainties as low as 10s, allowing us to reduce the uncertainty in the orbital period by a factor of two. Conclusions: A Bayesian analysis reveals that it is highly improbable that the observed transit times is explained by TTV, when compared with the simpler alternative of a linear ephemeris.Comment: Submitted to A&
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