Search Publications

Motion of the Ultraviolet R Aquarii Jet

Feibelman, W. A.; Hollis, J. M.; Dorband, J. E. +1 more

We present evidence for subarcsecond changes in the ultraviolet (~2550 Å) morphology of the inner 5 arcseconds of the R Aqr jet over a 2 yr period. These data were taken with the Hubble Space Telescope (HST) Faint Object Camera (FOC) when the primary mirror flow was still affecting observations. Images of the R Aqr stellar jet were successfully re…

The Nature and Origin of z_a ~ z_e Absorption Lines in the Redshift 0.20 Quasar, PKS 2135-147

Hamann, Fred; Cohen, Ross D.; Burbidge, E. M. +3 more

We use new UV and optical spectra and an archival Hubble Space Telescope Wide Field Planetary Camera 2 (HST-WFPC2) image to study the z_a ~ z_e absorber in the z_e ~ 0.20 QSO PKS 2135-147. The UV spectra, obtained with the Faint Object Spectrograph on HST, show strong z_a ~ z_e absorption lines of …

The Wave Experiment Consortium (wec)

Alleyne, H. St. C.; Thompson, J. A.; Gurnett, D. +13 more

Using energetic particles to probe the magnetic topology of ejecta

Richardson, I. G.

Observations of energetic particles over a wide range of rigidities can provide information on the presence of ejecta, and their structure. A large fraction of ejecta produce a local, few percent depression of the cosmic ray density. The depression typically extends over the ejecta region as determined from a range of ejecta signatures, in particu…

Star Formation and Metal Production as a Function of Redshift: The Role of the Multiphase ISM

Carollo, C. Marcella; Spaans, Marco

We present models of the cosmological star formation and metal production history of (proto)galaxies with varying axis ratios. More massive and/or roughly spherical systems reach the threshold metallicity for the transition to a multiphase interstellar medium earlier than less massive and/or more flattened systems. Therefore, more flattened and/or…

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.