Search Publications
An Empirical Procedure to Estimate Distances to Stellar Clusters
Allende Prieto, Carlos
A most desirable feature of a standard candle to estimate astronomical distances is robustness against changes in metallicity and age. It is argued that the radii of main-sequence stars with spectral types from solar to A0 show predictable changes with metallicity and detectable changes with evolution. Such stars populate the solar neighborhood an…
Properties of PACE-I HgCdTe Detectors in Space: The NICMOS Warm-Up Monitoring Program
Nota, A.; Calzetti, D.; Böker, T. +13 more
We summarize the results of a monitoring program which was executed following the cryogen exhaustion of the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on board the Hubble Space Telescope. During the subsequent warm-up, detector parameters such as detective quantum efficiency, dark current, bias offsets, and saturation levels have …
Jovicentric latitude effect on the bKOM radio emission observed by Ulysses/URAP
MacDowall, R. J.; Lecacheux, A.; Barrow, C. H.
During 1994 and into 1996, Ulysses was at distances of 5 AU or more from Jupiter and travelling from south to north of the ecliptic plane. At these distances, the jovian broadband radio emission (bKOM) was only received occasionally by the Unified Radio and Plasma Experiment (URAP) on board the Ulysses spacecraft. The signals were generally weak a…
Infall and Outflow Activities in the Be star FY CMa
Cao, Hui-Lai
Unusual activity of outflow mass motion connected with infall events was recorded for the B0.5 IVe star FY CMa in February 1987 from both archival IUE spectrograms of circumstellar N resonance lines and optical spectra of Hα and He λ5876 Å emission lines which showed inverse P Cygni-type profiles. We estimate the mass loss rate using ultraviolet S…
Low-Order p Modes From Virgo Irradiance Data
Finsterle, W.; Fröhlich, C.
Several candidates for low-order p modes (n ≤ 5) and possibly g modes were found by applying mode-detection techniques such as multivariate spectral regression analysis and time-frequency analysis to the VIRGO full-disc solar irradiance data. Three out of the candidates for low-order p modes could be confirmed by significant peaks in the un-treate…
Determination of physical properties of planetary sub-surface layers by artificial impacts and penetrometry
Kargl, G.; Ball, A. J.; Kömle, N. I.
In recent years the exploration of planetary bodies by surface probes has entered a new phase of interest. The mechanical properties of the near-surface layers of cometary and planetary bodies, including their strength, texture and layering, are important parameters needed both for a proper physical understanding of these bodies and for the design…
Perpendicular transport of charged particles in the heliosphere
Erdős, G.; Németh, Z.
We investigate spatial fractal structures of the Heliospheric Magnetic Field, using Ulysses magnetic field data. Fractal parameters of these structures are determined during the first off-ecliptic orbit of Ulysses. We construct a model magnetic field, which shows similar fractal characteristics than the magnetic field measurements. In the model fi…
Latitudinal gradients and charge sign dependent modulation of galactic cosmic rays
Kunow, H.; Wibberenz, G.; Ferreira, S. E. S. +7 more
Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in September 1997 and its second fast latitude scan in November 2000. At the time of the submission (May 2001) the spacecraft was located close to the heliographic equator at a radial distance of 1.3 AU. In contrast to the first orbit with the Sun declining to low activity, …
Three-Dimensional Solar Wind Modeling Using Remote-Sensing Data
Jackson, B. V.; Hick, P. P.
We have developed a computer-assisted tomography (CAT) technique that iteratively modifies a kinematic solar wind model to least-squares fit heliospheric remote sensing observations (interplanetary scintillation and Thomson-scattering observations). These remote sensing data cover a large range of solar elongations, and access high-latitude region…
Goddard High Resolution Spectrograph Observations of NGC 4151
Savage, B. D.; Ebbets, D. C.; Carpenter, K. G. +15 more
Goddard High Resolution Spectrograph observations of the nucleus of the bright, nearby Seyfert galaxy NGC 4151 are presented andbriefly described.