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Differential rotation and meridional flow in the solar supergranulation layer: Measuring the eddy viscosity
Küker, M.; Rüdiger, G.; Chan, K. L.
We measure the eddy viscosity in the outermost layers of the solar convection zone by comparing the rotation law computed with the Reynolds stress resulting from f-plane simulations of the angular momentum transport in rotating convection with the observed differential rotation pattern. The simulations lead to a negative vertical and a positive ho…
Radio observations of the XMM-Newton/Chandra 13hr deep survey field
Page, M. J.; Seymour, N.; Sasseen, T. +9 more
Our VLA observations of the XMM-Newton/Chandra 13hr deep survey field (see Page et al., this proceedings) result in one of the two deepest 1.4GHz radio maps ever made. Within the 15' radius field covered by the deep X-ray data (0.19 deg2), a total of 556 radio sources are detected, down to a 4sigma flux limit of 28mu Jy. Of the 214 Chan…
Coronal loops: Isothermal OR multithermal?
Schmelz, J. T.; Cirtain, J. W.; Beene, J. E. +5 more
Are coronal loops isothermal? A controversy over this question has arisen recently because different investigators using different techniques have obtained very different answers. Analysis of data using narrowband filter ratios to obtain temperature maps has produced several key publications that suggest that coronal loops may be isothermal. We ha…
Implementing TOPbase/Iron Project: continuous absorption from FeII
Bautista, Manuel; Cowley, Charles R.
We discuss implementation of TOPbase and Iron Project opacities for stellar spectral codes. We use a technique employed by Peach, where a Boltzmann-averaged cross-section is calculated for selected temperatures, and the opacity obtained from double interpolation in temperature and wavelength. It is straightforward to include all levels for which c…
The Operational Environment of the Hipparcos Mission
van Leeuwen, Floor; Penston, Margaret J.
We investigate links between the observational environment as experienced by the Hipparcos satellite and the performance of the spacecraft and payload instrumentation, with particular emphasis on finding out whether some of these effects may have been inadequately represented in instrument calibrations and could thus have affected the scientific r…
ISO observations of four active galaxies
Rigopoulou, D.; Dennefeld, M.; Spoon, H. W. W. +1 more
We present ISO PHOT-S spectra of four galaxies known or suspected to host a central AGN. Two of them are selected, among several others, from the initial Iras/Rosat sample of Boller et al. (\cite{Boller92}) because of their substantial X-ray emission, while no obvious Seyfert features was present in their optical spectra: IRAS 14201+2956 and IRAS …
In-flight performance of the IBIS calibration unit
Malaguti, G.; Bird, A. J.; Ubertini, P. +3 more
We describe the in-flight performance of the on-board calibration unit for the IBIS telescope on INTEGRAL. Both intrinsic performance and the quality of the calibration signals provided to the IBIS detector planes are discussed. The calibration unit intrinsic performance is assessed based on the diagnostic information in IBIS housekeeping. The flu…
Spectroscopic diagnostics of UV power and accretion in T Tauri stars
Brooks, D. H.; Costa, V. M.
It is known that in the upper atmospheres of the Sun and some late-type stars there is a systematic relationship between the optically thin total radiated power and the power emitted by single spectral lines. Using recently derived emission-measure distributions from IUE spectra for BP Tau, CV Cha, RY Tau, RU Lupi and GW Ori, we demonstrate that t…
Coronal densities and temperatures for cool stars in different stages of activity
Schmitt, J. H. M. M.; Audard, M.; Güdel, M. +1 more
With the advent of the new X-ray missions Chandra and XMM-Newton, high-resolution spectroscopy has become available for studies of stellar coronae. Individual lines can be used as diagnostic tools for measuring densities and temperatures in coronal plasma. In addition to the overall X-ray luminosity, spectroscopic properties can be used for a clas…
XMM-Newton observation of the Marano Field
Hasinger, G.; Wilms, J.; Staubert, R. +2 more