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Diffuse Dark and Bright Objects in the Hubble Deep Field
Park, Changbom; Kim, Juhan
In the Hubble Deep Field (HDF) we have identified candidate regions where primordial galaxies might be forming. These regions are identified from negative or positive peaks in the difference maps obtained from the HDF maps smoothed over 0.8" and 4". They have apparent V magnitudes typically between 29 and 31 (missing flux below the local average l…
EUV Spectral Variability and Non-Equilibrium Ionisation in the 'Quiet' Sun
Harrison, R. A.; Lanzafame, A. C.; Brooks, D. H. +2 more
Recent spectroscopic observations by the Solar and Heliospheric Observatory (SOHO) have revealed the dynamic nature of even the 'quiet' Sun. Spectral variability data clearly show that dynamics in the solar upper atmosphere take place on timescales shorter than those of ionisation relaxation. Accuracy in the interpretation of diagnostic spectral d…
Infrared Space Observatory Mapping of 60 Micron Dust Emission around Vega-Type Systems: Erratum
Stencel, R. E.; Backman, D. E.; Fajardo-Acosta, S. B.
In the Letter ``Infrared Space Observatory Mapping of 60 Micron Dust Emission around Vega-type Systems'' by S. B. Fajardo-Acosta, R. E. Stencel, and D. E. Backman (ApJ, 487, L151 [1997]), there is an error in the equatorial coordinates that we assigned to our maps. Using preliminary versions of the PHOT Interactive Analysis (PIA) program, we incor…
The Absolute Magnitude of RR Lyraes: from HIPPARCOS Parallaxes and Proper Motions
Solano, E.
We have used HIPPARCOS proper motions and the method of Statistical Parallax to estimate the absolute magnitude of RR Lyrae stars. In addition, we have used the HIPPARCOS parallax of RR Lyr itself to determine its absolute magnitude. These two results are in excellent agreement with each other and give a zero-point for the RR Lyrae Mv,[…
Effective Collision Strengths for Fine-Structure Transitions from the 3s23p5 2P Ground State of Chlorine-like Ni XII
Keenan, F. P.; Bell, K. L.; Matthews, A. +1 more
The R-matrix method is used to compute electron impact collision strengths for transitions in Ni XII from its ground-state fine-structure levels. Sophisticated configuration-interaction wave functions are used to represent the 14 lowest LS target states employed in the R-matrix expansion. By transforming the LS-coupled reactance matrices, and by a…
Electron Gyro Time Measurement Technique for Determining Electric and Magnetic Fields
Paschmann, G.; Vaith, H.; Frenzel, R. +1 more
The paper describes the technique the Electron Drift Instrument (EDI) on CLUSTER employs to measure the flight times of the electrons between the time they are emitted and the time they return after having completed a gyration in the ambient magnetic field. In the presence of an electric field two different trajectories exist which return to the d…
Spectroscopic binary orbits from ultraviolet radial velocities. Paper 28: Omicron Persei
Stickland, D. J.; Lloyd, C.
Measuring Magnetic Field Gradients From Four Point Vector Measurements in Space
Khurana, Krishan K.; Kivelson, Margaret G.; Kepko, Larry
The determination of all nine first order spatial gradients requires the knowledge of differences between the magnetic field measurements made simultaneously at (at least) four different points in space. As the first order differences between measurements are typically very small compared to the background field, even small errors resulting from a…
The ISO-Spectrum of the Young Star HD 100546
Vandenbussche, B.; Waelkens, C.; Malfait, K.
An Italian tracking station for Cassini
Ambrosini, R.; Grueff, G.
We present a feasibility study for a 64 m fully steerable parabolic radiotelescope capable of high efficiency operation at frequencies up to 100 GHz. If funds are made available, and construction rapidly started, the antenna would be available in time to be used as a tracking station for the Cassini radio science experiments.