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The nature of the optical continuum in NGC5128 (CentaurusA)
Storchi-Bergmann, Thaisa; Kinney, Anne L.; Bica, Eduardo +1 more
We present long-slit observations of NGC5128 in the range lambdalambda3200-9800Angstroms, covering the nucleus and dust lane across the east-west direction, up to ~2.2kpc from the nucleus. The reddening-corrected continua and absorption features, when compared with those typical of a bulge stellar population, show that all locations within 1.8kpc …
High S/N Echelle Spectroscopy in Young Stellar Groups. I. Observations and Data Reduction
Brown, A. G. A.; Le Poole, R. S.; David, M. +4 more
This is the first paper in a series in which we study the kinematical structure and dynamical evolution of OB associations and young stellar clusters. By means of high-resolution high-S/N spectroscopic observations, we aim at obtaining accurate stellar radial and rotational velocities and information on binarity in a selected number of such system…
Physical risks of landing on a cometary nucleus
Kührt, E.; Keller, H. U.; Knollenberg, J.
Comets originate from the outer solar system where the density and temperature of the planetary nebula were rather low. They form a distinct class of small solar system bodies and their physical properties differ considerably from those of any other known objects. The present knowledge of the cometary nucleus is cursory and driven more by imaginat…
Dynamic Processes in Be Star Atmospheres. V. Helium Line Emissions from the Outer Atmosphere of λ Eridani
Smith, Myron A.; Cohen, D. H.; Basri, G. +5 more
The He I lines of the mild B2e star λ Eri often exhibit rapid, small-amplitude emissions that can occur at random places in their photospheric lines, even when the star is in a ``nonemission state.'' New simultaneous observations of the triplet λ5876 and singlet λ6678 lines show that the emission ratio for these lines is near unity, contrary to th…
The Orbit of the Classical Cepheid V350 SGR
Evans, Nancy Remage; Sugars, Benjamin J. A.
We have obtained velocities for the binary Cepheid V350 Sgr at the David Dunlap Observatory. An orbit has been derived combining these data with velocities from the literature. The spectral type of B9.0 V has been confirmed from an IUE spectrum, leading to a mass of the companion of 2.5 Msun . The uncertainty in the mass is also discussed.
Merging 4 spacecraft data: concepts used for analysing discontinuities
Glassmeier, K. -H.; Dunlop, M. W.; Southwood, D. J. +2 more
Shocks and discontinuities in space plasmas have received much attention in both theoretical studies and spacecraft data analyses. The advent of multi-spacecraft missions, such as ISEE, have provided for a vast improvement of experimental information available on these structures. The ESA CLUSTER, multi-spacecraft mission presents the community wi…
A White Dwarf Companion to the B5 V Star HR 2875 (y Puppis)
Vennes, Stéphane; Christian, Damian J.; Berghöfer, Thomas W.
An extreme-ultraviolet source in the EUVE and ROSAT Wide Field Camera catalogs, also identified with a very soft ROSAT PSPC X-ray source, is coincident with the B5 V star HR 2875 (y Pup). We present an analysis of PSPC and EUVE spectra revealing the presence of a hot white dwarf companion to HR 2875, which then constitute the first confirmed B sta…
Impact Mechanics and Frequency of SL9-Type Events on Jupiter
Ahrens, Thomas J.; Roulston, Mark S.
A semianalytic model for the breakup of fragments of Comet Shoemaker-Levy 9 upon entry into Jupiter's atmosphere is presented. The model assumes that the impacting fragments behave as bodies of viscous fluid and that the dominant process in their breakup is the growth of hydrodynamic instabilities. It is shown that the size of the smallest instabi…
Solar modulation of galactic cosmic rays: the 3D heliosphere
Heber, Bernd; Potgieter, Marius S.; Ferrando, Philippe
The cosmic ray flux observed with the Kiel Electron Telescope onboard the Ulysses space probe varies with solar activity as well as with heliospheric position. The Ulysses' fast latitude scan performed in less than one year between September 1994 to August 1995 allowed us to obtain unique data about the latitudinal dependence of cosmic ray fluxes …
A Determination of The Nuclear Size of Comet Hale–Bopp (C/1995 O1)
Sekanina, Z.
The signal of the nucleus was digitally extracted from six images of the innermost coma of this comet, obtained with the Hubble Space Telescope's Wide-Field Planetary Camera 2 in the planetary mode between October 23, 1995 and October 17, 1996. Two different anisotropic, power-type laws were used to filter out the contribution from the dust coma: …