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Context. The unparalleled photometric data obtained by NASA's Kepler Space Telescope has led to improved understanding of red giant stars and binary stars. Seismology allows us to constrain the properties of red giants. In addition to eclipsing binaries, eccentric non-eclipsing binaries that exhibit ellipsoidal modulations have been detected with Kepler. Aims. We aim to study the properties of eccentric binary systems containing a red giant star and to derive the parameters of the primary giant component. Methods. We applied asteroseismic techniques to determine the masses and radii of the primary component of each system. For a selected target, light and radial velocity curve modelling techniques were applied to extract the parameters of the system and its primary component. Stellar evolution and its effects on the evolution of the binary system were studied from theoretical models. Results. The paper presents the asteroseismic analysis of 18 pulsating red giants in eccentric binary systems, for which masses and radii were constrained. The orbital periods of these systems range from 20 to 440 days. The results of our ongoing radial velocity monitoring programme with the Hermes spectrograph reveal an eccentricity range of e = 0.2 to 0.76. As a case study we present a detailed analysis of KIC 5006817, whose rich oscillation spectrum allows for detailed seismic analysis. From seismology we constrain the rotational period of the envelope to be at least 165 d, which is roughly twice the orbital period. The stellar core rotates 13 times faster than the surface. From the spectrum and radial velocities we expect that the Doppler beaming signal should have a maximum amplitude of 300 ppm in the light curve. Fixing the mass and radius to the asteroseismically determined values, we find from our binary modelling a value of the gravity darkening exponent that is significantly larger than expected. Through binary modelling, we determine the mass of the secondary component to be, SCOPUS: ar.j, info:eu-repo/semantics/published

Resting-state studies in depressed patients have revealed increased connectivity within the default mode network (DMN) and task-positive network (TPN). This has been associated with heightened rumination, which is the tendency to repetitively think about symptoms of distress. Here, we performed a pharmacological neuroimaging study in healthy volunteers to investigate whether short-term antidepressant administration could reduce DMN connectivity. We recorded resting-state functional magnetic resonance imaging (fMRI) scans in twenty-three healthy volunteers after two week intake of the combined serotonin-norepinephrine reuptake inhibitor (SNRI) duloxetine in a double-blind, placebo-controlled, crossover study. Duloxetine improved mood in part as a result of increased resilience to the mood-worsening effects of scanning and reduced DMN and TPN connectivity. Within the DMN, duloxetine reduced connectivity between the medial prefrontal cortex (MPFC) and the lateral parietal cortex (LPC) and uncoupled the MPFC from the dorsolateral prefrontal cortex (DLPFC). Within the TPN, duloxetine uncoupled the intraparietal sulcus (IPS) from the inferior occipital gyrus. These results show that two-week antidepressant administration reduces DMN and TPN connectivity in healthy volunteers, which may contribute to their antidepressant effects in depression.

Aims. Our goal is to study the different morphologies associated to the interaction of the stellar winds of AGB stars and red supergiants with the interstellar medium (ISM) to follow the fate of the circumstellar matter injected into the interstellar medium. Methods. Far-infrared Herschel/PACS images at 70 and 160 μm of a sample of 78 Galactic evolved stars are used to study the (dust) emission structures developing out of stellar wind-ISM interaction. In addition, two-fluid hydrodynamical simulations of the coupled gas and dust in wind-ISM interactions are used for comparison with the observations. Results. Four distinct classes of wind-ISM interaction (i.e. "fermata", "eyes", "irregular", and "rings") are identified, and basic parameters affecting the morphology are discussed. We detect bow shocks for ∼40% of the sample and detached rings for ∼20%. The total dust and gas mass inferred from the observed infrared emission is similar to the stellar mass loss over a period of a few thousand years, while in most cases it is less than the total ISM mass potentially swept-up by the wind-ISM interaction. De-projected stand-off distances (R 0)-defined as the distance between the central star and the nearest point of the interaction region-of the detected bow shocks ("fermata" and "eyes") are derived from the PACS images and compared to previous results, model predictions, and the simulations. All observed bow shocks have stand-off distances smaller than 1 pc. Observed and theoretical stand-off distances are used together to independently derive the local ISM density. Conclusions. Both theoretical (analytical) models and hydrodynamical simulations give stand-off distances for adopted stellar properties that are in good agreement with the measured de-projected stand-off distance of wind-ISM bow shocks. The possible detection of a bow shock-for the distance-limited sample-appears to be governed by its physical size as set roughly by the stand-off distance. In particular the s, SCOPUS: ar.j, info:eu-repo/semantics/published

Context. In massive binaries, the powerful stellar winds of the two stars collide, leading to the formation of shock-dominated environments that can be modeled only in 3D. Aims. We investigate the morphology of the collision-front shell between the stellar winds of binary components in two long-period binary systems, one consisting of a hydrogen-rich Wolf-Rayet star (WNL) and an O-star and the other of a luminous blue variable (LBV) and an O-star.We follow the development and evolution of instabilities due to both the wind interaction and the orbital motion, that form in this shell if it is sufficiently compressed. Methods. We use MPI-AMRVAC to time-integrate the equations of hydrodynamics, combined with optically thin radiative cooling, on an adaptive mesh 3D grid. Using parameters for generic binary systems, we simulate the interaction between the winds of the two stars. Results. TheWNL + O star binary represent a typical example of an adiabatic wind collision. The resulting shell is thick and smooth, showing no instabilities. On the other hand, the shell created by the collision of the O star wind with the LBV wind, as well as the orbital motion of the binary components, is susceptible to thin shell instabilities, which create a highly structured morphology. We identify the instabilities as both linear and non-linear thin-shell instabilities, there being distinct differences between the leading and the trailing parts of the collision front. We also find that for binaries containing a star with a (relatively) slow wind, the global shape of the shell is determined more by the slow wind velocity and the orbital motion of the binary, than the ram pressure balance between the two winds. Conclusions. Additional parametric studies of the interaction between the massive binary winds are needed to identify the role and dynamical importance of multiple instabilities at the collision front, as shown here for an LBV + O star system.