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The Cluster Spatio-Temporal Analysis of Field Fluctuations (STAFF) Experiment
de Conchy, Y.; Parrot, M.; Rezeau, L. +20 more
Detection of ozone on Saturn's satellites RHEA and Dione
Johnson, R. E.; Cruikshank, D. P.; Pendleton, Y. J. +2 more
The satellites Rhea and Dione orbit within the magnetosphere of Saturn, where they are exposed to particle irradiation from trapped ions. A similar situation applies to the galilean moons Europa, Ganymede and Callisto, which reside within Jupiter's radiation belts. All of these satellites have surfaces rich in water ice. Laboratory studies of the …
Luminosities of SX Phoenicis, Large-Amplitude Delta Scuti, and RR Lyrae Stars
McNamara, D.
Strömgren _uvbyβ photometry of SX Phoenicis and large-amplitude δ Scuti variables is analyzed to determine the mean temperatures, metal abundances, and surface gravities of the stars. The mean temperatures and fundamental periods are used in conjunction with the pulsation equation and stellar models to derive masses, radii, surface gravities, and …
The Evolution of Galactic Boron and the Production Site of the Light Elements
Deliyannis, Constantine P.; Primas, F.; Rebull, L. M. +5 more
The Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) has been used to obtain spectra of the 2500 Å region in eight stars with metallicities ranging from [Fe/H] = -0.4 to -3.0, including the most metal-poor star ever observed for boron. Spectrum synthesis utilizing latest Kurucz model atmospheres has been used to dete…
Anomalously small magnetic field in the local interstellar cloud
Gloeckler, George; Geiss, Johannes; Fisk, L. A.
The solar wind carves out a cavity, known as the heliosphere, in the warm local interstellar cloud, which is itself embedded in a larger hot cloud. It is generally assumed that there is an overall pressure balance between these three regions. Thermal pressure and magnetic field pressure in the local interstellar cloud should therefore balance the …
The optical counterpart of the isolated neutron star RX J185635-3754
Walter, Frederick M.; Matthews, Lynn D.
The extreme densities of neutron stars make them an ideal system in which to investigate the equation of state of nuclear matter; accurate determinations of neutron star masses and radii are crucial for this. Current observations of neutron stars in binary systems yield masses that are generally consistent with theory. But measurements of radii ar…
First results of ISO-SWS observations of Saturn: detection of CO_2_, CH_3_C_2_H, C_4_H_2_ and tropospheric H_2_O.
Beintema, D. A.; Lellouch, E.; Encrenaz, T. +16 more
The spectrum of Saturn has been recorded between 4.5 and 16.0µm with the grating mode of the Short-Wavelength Spectrometer (SWS) of ISO. The resolving power is 1500. The main results of this observation are (1) the detection of CO_2_, CH_3_C_2_H and C_4_H_2_ in the stratosphere and (2) the detection of H_2_O in the troposphere. In the 4.5-5.…
High Spatial Resolution Imaging of Pre-Main-Sequence Binary Stars: Resolving the Relationship between Disks and Close Companions
Ghez, A. M.; White, Russel J.; Simon, M.
In order to study the passive and active effects of young close companion stars and to constrain possible multiple star formation mechanisms, we have carried out a high-resolution imaging program of six multiple T Tauri star systems using the Hubble Space Telescope from 0.3 to 0.9 µm and ground-based speckle imaging from 1 to 2 µm. Eac…
Determining the Hubble Constant from the Gravitational Lens PG 1115+080
Keeton, C. R.; Kochanek, C. S.
For the quadruple gravitational lens PG 1115+080, we combine recent measurements of the time delays with new lens models to determine the Hubble constant H0. We explore the effects of systematic uncertainties in the lens models on the estimates of H0, and we discuss how the uncertainties can be reduced by future observations.…
Cepheid Calibration of the Peak Brightness of Type Ia Supernovae. VIII. SN 1990N in NGC 4639
Panagia, N.; Saha, A.; Labhardt, Lukas +3 more
Repeated imaging observations have been made of NGC 4639 with the Hubble Space Telescope between 1995 April and July over an interval of 71 days. Images were obtained on 12 epochs in the F555W band and on two epochs in the F814W band. The galaxy is parent to the prototypical Type Ia supernova SN 1990N. A total of 18 definite and six likely Cepheid…