4,630 research outputs found

    La Flora aeròbia de les apendicitis cròniques

    Get PDF

    Photospheric activity, rotation and magnetic interaction in LHS 6343 A

    Full text link
    Context. The Kepler mission has recently discovered a brown dwarf companion transiting one member of the M4V+M5V visual binary system LHS 6343 AB with an orbital period of 12.71 days. Aims. The particular interest of this transiting system lies in the synchronicity between the transits of the brown dwarf C component and the main modulation observed in the light curve, which is assumed to be caused by rotating starspots on the A component. We model the activity of this star by deriving maps of the active regions that allow us to study stellar rotation and the possible interaction with the brown dwarf companion. Methods. An average transit profile was derived, and the photometric perturbations due to spots occulted during transits are removed to derive more precise transit parameters. We applied a maximum entropy spot model to fit the out-of-transit optical modulation as observed by Kepler during an uninterrupted interval of 500 days. It assumes that stellar active regions consist of cool spots and bright faculae whose visibility is modulated by stellar rotation. Results. Thanks to the extended photometric time series, we refine the determination of the transit parameters and find evidence of spots that are occulted by the brown dwarf during its transits. The modelling of the out-of-transit light curve of LHS 6343 A reveals several starspots rotating with a slightly longer period than the orbital period of the brown dwarf, i.e., 13.13 +- 0.02 days. No signature attributable to differential rotation is observed. We find evidence of a persistent active longitude on the M dwarf preceding the sub- companion point by 100 deg and lasting for at least 500 days. This can be relevant for understanding how magnetic interaction works in low-mass binary and star-planet systems.Comment: 14 pages, 16 figure

    The initial-final mass relationship of white dwarfs in common proper motion pairs

    Get PDF
    A promising approach to decrease the uncertainties in the initial-final mass relationship, which is still poorly constrained, is to study white dwarfs for which external constraints are available, for instance, white dwarfs in common proper motion pairs (CPMPs). Important information of the white dwarf can be inferred from the study of the companion, since they were born at the same time and with the same initial chemical composition. In this contribution, we report new results obtained from spectroscopic observations of both members of several CPMPs composed of a F, G or K type star and a DA white dwarf

    Unveiling the Price of Obscenity: Evidence from Closing Prostitution Windows in the Netherlands

    Get PDF
    This paper quantifies the aversion of residents to on-site prostitution. To establish causality, we first exploit the fact that Amsterdam's Red Light Districts (RLDs) are delimited by canals, together with a policy that closed several prostitution windows since 2007. Using a two-dimensional difference-in-discontinuity estimator, we find that households require at least 6,000 euros/year to be right next to a brothel. To estimate the economic impact outside the RLD, we also look at the closings of all brothels in Utrecht in 2013. Using a spatial difference-in-slope estimator, the effect on house prices is found to be heterogeneous and some households pay up to 1,600 euros/year to be distant from prostitution. Both cities also experienced crime reduction in the RLDs, but the explained changes in house prices are mostly driven by drug-related crimes and minor nuisances. In Amsterdam, more than 70% of the discount applied to houses beside brothels remains unexplained

    Intercomparison of carbonate chemistry measurements on a cruise in northwestern European shelf seas

    Get PDF
    Four carbonate system variables were measured in surface waters during a cruise aimed at investigating ocean acidification impacts traversing northwestern European shelf seas in the summer of 2011. High-resolution surface water data were collected for partial pressure of carbon dioxide (pCO2; using two independent instruments) and pH using the total pH scale (pHT), in addition to discrete measurements of total alkalinity and dissolved inorganic carbon. We thus overdetermined the carbonate system (four measured variables, two degrees of freedom), which allowed us to evaluate the level of agreement between the variables on a cruise whose main aim was not intercomparison, and thus where conditions were more representative of normal working conditions. Calculations of carbonate system variables from other measurements generally compared well with direct observations of the same variables (Pearson’s correlation coefficient always greater than or equal to 0.94; mean residuals were similar to the respective accuracies of the measurements). We therefore conclude that four of the independent data sets of carbonate chemistry variables were of high quality. A diurnal cycle with a maximum amplitude of 41 μatm was observed in the difference between the pCO2 values obtained by the two independent analytical pCO2 systems, and this was partly attributed to irregular seawater flows to the equilibrator and partly to biological activity inside the seawater supply and one of the equilibrators. We discuss how these issues can be addressed to improve carbonate chemistry data quality on future research cruises
    • …
    corecore