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Fast-rotating nearby solar-type stars, Li abundances and X-ray luminosities. I. Spectral classification, v sin i, Li abundances and X-ray luminosities
Tagliaferri, G.; Pasquini, L.; de Medeiros, J. R. +3 more
We present the results of high-resolution spectroscopic and high-precision photometric observations on a sample of 129 late-F and G-type nearby stars selected on the basis of their large rotational velocity. Using also data from the Hipparcos satellite, CORAVEL and from the ROSAT satellite database, we infer spectral types, compute radial velociti…
Hubble Space Telescope Observations of Proper Motions in Herbig-Haro Objects 1 and 2
Hartigan, Patrick; Bally, John; Morse, Jon +3 more
Hubble Space Telescope observations obtained in 1994 and 1997 are used to measure proper motions in the HH 1/2 protostellar outflow in Orion. Since the HH 1/2 system lies within 10° of the plane of the sky, proper motions provide accurate measures of true space velocities. Comparison of the 1994 and 1997 images reveals a variety of changes such as…
Doppler Imaging of stellar magnetic fields. III. Abundance distribution and magnetic field geometry of alpha 2 CVn
Ilyin, I.; Piskunov, N.; Kochukhov, O. +2 more
We used the new magnetic Doppler Imaging code to reconstruct the magnetic field geometry and surface abundance distributions for the classical magnetic CP star alpha 2 CVn. High-resolution spectropolarimetric observations in the Stokes I and V parameters were collected with the SOFIN échelle spectrograph at the Nordic Optical Telescope.…
The Inadequacy of Temperature Measurements in the Solar Corona through Narrowband Filter and Line Ratios
Schmelz, J. T.; Martens, P. C. H.; Cirtain, J. W.
We analyze the determination of coronal line-of-sight temperatures with the technique of narrowband filter ratios that is currently employed for data obtained with the Transition Region and Coronal Explorer and the EUV Imaging Telescope on board the Solar and Heliospheric Observatory. We demonstrate that the simple fact that the observed different…
The relation of PAH strength with cold dust in galaxies
Bianchi, S.; Klaas, U.; Haas, M.
Mid-infrared spectra and submillimetre maps are investigated for five galaxies covering a range of star forming activity. We find a good spatial coincidence between the 850 mu m continuum emission and the strength of the PAH 7.7 mu m line. The PAH 7.7 mu m peak to 850 mu m flux ratio lies in the range around 2 with a moderate dispersion across the…
Structural Parameters for Globular Clusters in NGC 5128
Holland, Stephen T.; Harris, William E.; Harris, Gretchen L. H. +1 more
We present new imaging measurements of 27 individual globular clusters in the halo of the nearby elliptical galaxy NGC 5128, obtained with the Hubble Space Telescope Imaging Spectrograph and Wide Field Planetary Camera 2. We use the cluster light profiles to determine their structural parameters (core and half-light radii, central concentration, a…
The First Detections of the Extragalactic Background Light at 3000, 5500, and 8000 Å. III. Cosmological Implications
Madore, Barry F.; Freedman, Wendy L.; Bernstein, Rebecca A.
We have used the Hubble Space Telescope Wide Field and Planetary Camera 2 in combination with ground-based spectroscopy to measure the integrated flux of galaxies at optical wavelengths-the extragalactic background light (EBL). We have also computed the integrated light from individual galaxy counts in the images used to measure the EBL and in the…
Ulysses' second fast-latitude scan: Complexity near solar maximum and the reformation of polar coronal holes
Balogh, A.; Reisenfeld, D. B.; McComas, D. J. +5 more
Ulysses' second fast latitude scan, near solar maximum, comprises a complicated mixture of solar wind flows from a variety of sources at high southern as well as low heliolatitudes. In contrast, observations northward of ~40° N show the reformation of relatively steady fast solar wind flows, which are virtually indistinguishable from the polar cor…
X-Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 with Chandra
Brandt, W. N.; Garmire, G. P.; Chartas, G. +2 more
With 40 ks of Chandra ACIS-S3 exposure, new information on both the starburst and QSO components of the X-ray emission of Markarian 231, an ultraluminous infrared galaxy and broad absorption line QSO, has been obtained. The bulk of the X-ray luminosity is emitted from an unresolved nuclear point source, and the spectrum is remarkably hard, with th…
The Orientation of Jets Relative to Dust Disks in Radio Galaxies
Clarke, C. J.; Pringle, J. E.; Schmitt, H. R. +1 more
We use Hubble Space Telescope broadband images and VLA and VLBI continuum data to study the three-dimensional orientation of jets relative to nuclear dust disks in 20 radio galaxies. The comparison between the position angles of the jets and those of the dust disk major axes shows a wide distribution, suggesting that they are not aligned preferent…