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The solar disk spectrum between 660 and 1175 Anstroms (first order) obtained by SUMER on SOHO
Wilhelm, K.; Curdt, W.; Lemaire, P. +3 more
SUMER -- Solar Ultraviolet Measurements of Emitted Radiation -- onboard of SOHO -- Solar and Heliospheric Observatory -- obtained its first spectrum on January 25, 1996 near the north polar limb. The range from 660 Angstroms to 1175 Angstroms which has never before been observed with such a good spectral resolution contains a wealth of spectroscop…
An adaptive grid code for high resolution 1-D hydrodynamics of the solar and stellar transition region and corona
Peres, G.; Reale, F.; Betta, R. +1 more
We present a new version of the Palermo-Harvard hydrodynamic model of plasma confined in coronal loops, based on a regridding algorithm which ensures limited variations of thermodynamical variables across grid points. The code provides an accurate description of the dynamics of the chromosphere-corona transition region, in spite of the very steep …
Radial velocities and iron abundances of field RR Lyraes. I.
Barnes, T. G.; Fernley, J.
We present systemic velocities and iron abundances for 56 RR Lyraes, the majority of which have been observed by the HIPPARCOS satellite. Comparison between our systemic velocities and previous values identifies several binary candidates only one of which, TU UMa, was previously suspected of being a binary. However, spectra of the unusual RR Lyrae…
Mesures de vitesses radiales. VIII. Accompagnement AU sol du programme d'observation du satellite HIPPARCOS
Duflot, M.; Burnage, R.; Genty, V. +2 more
We publish 1879 radial velocities of stars distributed in 105 fields of 4^{\circ} \times 4^{\circ}. We continue the PPO series \cite[(Fehrenbach et al. 1987;]{Feh87} \cite[Duflot et al. 1990, 1992 and 1995),]{Du90} using the Fehrenbach objective prism method. Table 1 only available in electronic form at CDS via to cdsarc.u-strasbg.fr (130.79.128.5…
Analyzing X-ray variability by linear state space models
Timmer, J.; Konig, M.
In recent years, autoregressive models have had a profound impact on the description of astronomical time series as the observation of a stochastic process. These methods have advantages compared with common Fourier techniques concerning their inherent stationarity and physical background. However, if autoregressive models are used, it has to be t…
Radial velocities and iron abundances of field RR Lyraes. II.
Garrido, R.; Solano, E.; Barnes, T. G. +1 more
This is the second of the papers devoted to derive radial velocities and iron abundances of field RR Lyraes observed by HIPPARCOS. Our abundances show good agreement with those in the literature obtained both from photometric (Delta S index) and spectroscopic methods. Binary candidates and stars misclassified as RR Lyraes in the original HIPPARCOS…
A photometric and spectroscopic study of the association LH47 in the superbubble N44 in the LMC
Bomans, D. J.; Dieball, A.; Will, J. -M.
The OB association LH47 inside the superbubble N44 in the Large Magellanic Cloud (LMC) is analyzed with CCD photometry. For the bright blue stars spectra in the optical and UV have been taken. The observed U, B, and V magnitudes and colours are converted to Teff and L. From isochrone fits to the colour magnitude diagram (CMD), we find a…
Mass determination of astrometric binaries with Hipparcos. I. Theory and simulation
Mignard, F.; Martin, C.; Froeschle, M.
The analysis of the observations of double stars made by the ESA satellite Hipparcos has involved a very specific processing to derive the relevant astrometric parameters. This required to distinguish between several categories of double stars according to the separation and orbital motion. We show that for close pairs with orbital period less tha…
Ultraviolet variability of the Seyfert 1 galaxy Fairall 9
Clavel, J.; Rodriguez-Pascual, P. M.; Wamsteker, W. +5 more
The large amplitude of the variations of the Seyfert I Galaxy Fairall-9 between 1978 and 1991 make this Active Galaxy especially suitable for a combined study in terms of reverberation analysis and photoionization modeling over the velocity field of the broad lines of its ultraviolet spectrum. We have combined our ultraviolet data with those avail…
Absolute proper motions for the calibration of the HIPPARCOS proper motion system
Klemola, A. R.; Geffert, M.; Schmoll, J. +1 more
Absolute proper motions of 48 Hipparcos stars in nine fields distributed over the northern hemisphere are presented. The proper motions have been recently used as part of the Bonn program for the extragalactic link of the Hipparcos proper motion system. We describe methods which have led to the absolute proper motions of the major part of the Bonn…