Search Publications
The Hubble Constant
Mould, Jeremy
With the completion of the Hubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale, it is interesting to form the dimensionless quantity H 0 t 0 by multiplying the Hubble Constant by the age of the Universe. In a matter dominated decelerating Universe with a density exceeding 0.26 of the critical value, H…
Cosmic Ray Effects on the ISOCAM Long Wave Detector
Claret, A.; Dzitko, H.; Engelmann, J.
The ISOCAM detector is subjected to transient effects induced by cosmic rays, the so-called glitches. This paper is focused on the ISOCAM long wave detector. The predicted glitch rates have been re-evaluated by taking into account secondary particles production in the materials surrounding the LW detector. We show in this preliminary study that th…
Comparison of coordinates and proper motion of FONAC stars with HIPPARCOS and CMC11 data
Yatsenko, A. I.
The (FONAC - Hic) and (FONAC - CMC11) differences of coordinates and proper motions were considered as orthogonal functions dependent on equatorial coordinates and magnitude of stars. After the systematic part of the expansions is taken into account the root-mean-square differences (FONAC - CMC11) are, on the average, 0.24'' in both coordinates fo…
Ulysses Observations of Nonlinear Wave-wave Interactions in the Source Regions of Type III Solar Radio Bursts
MacDowall, R. J.; Thejappa, G.
The Ulysses Unified Radio and Plasma Wave Experiment (URAP) has observed Langmuir, ion-acoustic and associated solar type III radio emissions in the interplanetary medium. Bursts of 50–300 Hz (in the spacecraft frame) electric field signals, corresponding to long-wavelength ion-acoustic waves are often observed coincident in time with the most int…
Dynamics in Restructuring Active Regions Observed During Soho/Yohkoh/Gbo Campaigns
Mandrini, C. H.; Nitta, N.; Fletcher, L. +6 more
JOP17 and JOP 33 are SOHO Joint Observing Programs in collaboration with Yohkoh/SXT and ground based observatories (GBO's), dedicated to observe dynamical events through the atmosphere. During runs of these programs we observed in restructuring active regions (ARs), surges, subflares, bright knots, but not large flares and jets. From these observa…
An IUE Archival Study of the White Dwarf Temperature Variation in the Dwarf Nova WZ Sagittae
Sion, E. M.; Cheng, F. H.; Slevinsky, R. J. +2 more
The IUE archive offers a series of far UV spectra of ultra-short period dwarf nova WZ Sge over a long time baseline and hence the opportunity to monitor the ongoing accretion, the cooling of the white dwarf and temporal variations in the line spectra. We have carried out a quantitative analysis of these spectra including model atmosphere simulatio…
Ultimate sensitivity with ISOCAM
Altieri, B.; Aussel, H.; Elbaz, D. +3 more
We discuss the instrumental factors which constrain the sensitivity limits of the mid-infrared camera (ISOCAM) of ESA's Infrared Space Observatory (ISO). The observing strategy judged to be best suited to faint-source detection is described. A data analysis technique adapted to the extraction of the faintest point-sources is discussed. We report t…
Ultraviolet Emission Lines in BA and Non-BA Giants
Robinson, Richard D.; Carpenter, Kenneth G.; Böhm-Vitense, Erika
With the Hubble Space Telescope (HST) and the Goddard High Resolution Spectrograph we have observed four barium and three weak barium stars in the ultraviolet spectral region, together with two nonpeculiar giant standard stars. An additional suspected Ba star was observed with HST and the Space Telescope Imaging Spectrograph. In the H-R diagram, t…
SWS-Detector Glitch Effect Correction
Wiezorrek, E.; Wieprecht, E.; Haser, L.
We describe how the ISO-SWS (Infrared Space Observatory - Short Wavelength Spectrometer) software packages detect various glitch events i.e. high energy particle hits effecting the SWS detectors. A rough classification of glitch types is given. The events cause an instantaneous change in the slope of the SWS detector read outs followed by a distor…
delta Scuti stars in stellar systems: On the variability of HD 220392 and HD 220391
Lampens, P.; Sinachopoulos, D.; Van Camp, M.
HD 220392 (HR 8895), the brightest member of the visual double star CCDM 23239-5349, is a new short-period variable bright star, probably of the delta Scuti type. The period analysis performed on the complete set of definitive Geneva photometry as well as on the data obtained at the ESO 0.5m telescope shows two periodicities of about 4.7 and 5.5 c…