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A test of Hipparcos parallaxes on multiple stars
Tokovinin, A. A.; Shatskii, N. I.
The dynamical parallaxes of visual binary stars with reliable orbits selected from the multiple star catalog are compared with their Hipparcos trigonometric parallaxes. 141 objects with errors in the Hipparcos parallaxes no larger than 2.5 mas are divided into three groups by the quality of their orbits and by the reliability of the Hipparcos comp…
Illumination in Symbiotic Binary Stars: Non-LTE Photoionization Models. II. WIND Case
Raymond, John C.; Kenyon, Scott J.; Proga, Daniel
We describe a non-LTE photoionization code to calculate the wind structure and emergent spectrum of a red giant wind illuminated by the hot component of a symbiotic binary system. We consider spherically symmetric winds with several different velocity and temperature laws and derive predicted line fluxes as a function of the red giant mass-loss ra…
The molecular cloud core M17-North: ISO spectroscopy and IR/mm continuum mapping
Henning, Th.; Lemke, D.; Launhardt, R. +2 more
We present the first complete infrared spectrum of a molecular cloud core covering the wavelength region from 2.4 up to 200mu m together with a map at 1.3mm wavelength and near-infrared (NIR) images. The core is located in the northern part of
X-ray spectroscopy of the active giant beta Ceti: the SAX LECS view
Peres, G.; Favata, F.; Sciortino, S. +1 more
We present an X-ray observation of the active giant beta Cet, performed with the Low Energy Concentrator Spectrometer (LECS) on-board the SAX satellite. The resulting X-ray spectrum is well fit by an optically-thin plasma model with two discrete temperatures, and the inferred coronal metallicity is compatible both with the abundances derived from …
Ion energy equation for the high-speed solar wind: Ulysses observations
Balogh, A.; McComas, D. J.; Goldstein, B. E. +4 more
Ulysses data in the high-speed solar wind that cover a wide range of latitudes centered on the solar poles were studied to test whether a polytrope law can be used to close the ion energy equation. Three approaches were taken. We determined the correlation between proton temperature and density (1) in the free expansion of the high-speed solar win…
A pair of forward and reverse slow-mode shocks detected by Ulysses at ∼5 AU
Lakhina, G. S.; Tsurutani, B. T.; Smith, E. J. +6 more
We report the first finding of a pair of forward and reverse slow-mode shocks in the distant heliosphere using plasma and magnetic field data from the Ulysses spacecraft located at 5.3 AU and 9°S heliolatitude. The slow-mode shocks are found to occur in a compressed magnetic field (low plasma ) region within a co-rotating interaction region (CIR).…
EUV Spectroscopy of the Sunspot Region NOAA 7981 Using SOHO - II. Velocities and Line Profiles
Harrison, R. A.; Wilhelm, K.; Fredvik, T. +8 more
We have studied the dynamics in the sunspot transition region between the chromosphere and the corona and investigated the extension of the flow field into the corona. Based on EUV spectra of a medium size sunspot and its surroundings, NOAA 7981, observed with CDS and SUMER on SOHO, we derive line-of-sight velocities and study the line profiles fo…
ISOCAM Mid-Infrared Imaging of the Quiescent Spiral Galaxy NGC 7331
Smith, Beverly J.
Using the mid-infrared camera (ISOCAM) on the Infrared Space Observatory (ISO), the Sb LINER galaxy NGC 7331 has been imaged in two broadband and four narrowband filters between 6.75 and 15 µm. These maps show a prominent circumnuclear ring of radius 0.25 arcmin × 0.75 arcmin (1.1 × 3.3 kpc) encircling an extended central source. The 7.7 and…
Deep Optical Imaging of the Bright Seyfert Galaxy NGC 5548: A Long, Very Low Surface Brightness Tail
Glazebrook, Karl; Tyson, J. Anthony; Fischer, Philippe +9 more
Deep Hubble Space Telescope Wide Field Camera (WFC-1) imaging of a region 3.7‧ east of the V = 13 mag Seyfert galaxy NGC 5548 in the F555W and F785LP bands, and deep ground-based V and I imaging, show a new extended, blue, low surface brightness structure, apparently a remnant of a tidal interaction associated with NGC 5548. If this straight, low …
A search for substellar companions around nine weak-lined T-Tauri stars with the Planetary Camera 2 of the Hubble Space Telescope
Torres, Guillermo; Latham, David W.; Sartoretti, Paola +1 more
To search for substellar companions, we have obtained I-band images of 9 weak-lined T-Tauri stars in the Taurus-Auriga star-forming region using the Planetary Camera 2 of the Hubble Space Telescope. Except for a stellar companion close to HBC 407, we found no companions within 8arcsec of any of our targets. We did find 23 faint objects outside a s…