1,137 research outputs found

    Calibrating damping rates with LEGACY linewidths

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    Linear damping rates of radial oscillation modes in selected KeplerKepler stars are estimated with the help of a nonadiabatic stability analysis. The convective fluxes are obtained from a nonlocal, time-dependent convection model. The mixing-length parameter is calibrated to the surface-convection-zone depth of a stellar model obtained from fitting adiabatic frequencies to the LEGACY observations, and two of the three nonlocal convection parameters are calibrated to the corresponding LEGACY linewidth measurements. The atmospheric structure in the 1D stability analysis adopts a temperature-optical-depth relation derived from 3D hydrodynamical simulations. Results from 3D simulations are also used to calibrate the turbulent pressure and to guide the functional form of the depth-dependence of the anisotropy of the turbulent velocity field in the 1D stability computations.Comment: 4 pages, 4 figures, refereed conference proceedings, "Seismology of the Sun and the Distant Stars 2016", M\'ario J.P.F.G. Monteiro, Margarida S. Cunha, Jo\~ao M.T. Ferreira (eds), EPJ Web of Conference

    On the seismic age and heavy-element abundance of the Sun

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    We estimate the main-sequence age and heavy-element abundance of the Sun by means of an asteroseismic calibration of theoretical solar models using only low-degree acoustic modes from the BiSON. The method can therefore be applied also to other solar-type stars, such as those observed by the NASA satellite Kepler and the planned ground-based Danish-led SONG network. The age, 4.60+/-0.04 Gy, obtained with this new seismic method, is similar to, although somewhat greater than, today's commonly adopted values, and the surface heavy-element abundance by mass, Zs=0.0142+/-0.0005, lies between the values quoted recently by Asplund et al. (2009) and by Caffau et al. (2009). We stress that our best-fitting model is not a seismic model, but a theoretically evolved model of the Sun constructed with `standard' physics and calibrated against helioseismic data.Comment: 16 pages, 11 figures, 5 tables, accepted for publication in MNRA

    When Heritage Preservation Meets Living Memory: Constructing the Medina of Fez as a World Heritage Heterotopia

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    This project engages the UNESCO World Heritage program\u27s international place-making and heritage preservation campaign, and the processes that are carried out to transform an everyday cultural place into a World Heritage site. I consider what effects these preservation projects and the tourists they attract have on communities of living memory, while also engaging non-Western conceptions of heritage and the local processes for how it is preserved or produced in such contexts. To these ends, I look at one of the first non-Western urban sites to be inscribed on the World Heritage list-- the Medina of Fez, Morocco. The Medina offers a rich site for this analysis given its complex history as a preservation project, its status as the cultural capital of Morocco, and for a number of other reasons. I ask how preservation practices and protocols, as well as various discourses together construct the Medina as a World Heritage city and through what means is this spatial dynamic sustained. I also examine the effects of this Western driven global place-making and heritage preservation campaign employed within a non-Western place of living memory and memory practices. Through engaging these questions, I offer both a top-down (text-based analysis) and a bottom-up analysis (embodied spatial analysis) that draws from Foucaultian spatial theory, Michel de Certeau\u27s poetics of space, and from literature in rhetorical studies and critical heritage studies. What follows is a three-part discussion of how the World Heritage place-making and preservation practices constitute a preservationist apparatus that renders heterotopic effects, how the heterotopia is grounded and sustained by the pedestrian rhetorics of tourists, local discourse, material preservation. Further, I engage how local meaning-making and memory work in the Medina of Fez offers a different understanding of how heritage is preserved and produced