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The β Pictoris circumstellar disk. XVII. Physical and chemical parameters of the disk.
Deleuil, M.; Ferlet, R.; Vidal-Madjar, A. +3 more
New high resolution spectroscopic observations in the visible as well as archival HST UV data are used to investigate some physical and chemical properties of the disk around β Pictoris . A number of circumstellar lines are detected for the first time: Fe I , as well as weak lines of Fe II , Mn II and Zn II . Reliable estimates of the total gaseou…
New global solution of Earth orientation parameters from optical astrometry in 1900-1990.
Pesek, I.; Vondrak, J.; Ron, C. +1 more
Astrometrically observed variations of latitude and Universal time with thirty instruments of different types, located at 19 observatories all over the world, are used to derive polar motion, UT1-TAI (since 1956) and celestial pole offset at 5-day intervals. The values based on the observations of individual stars are used, the model of least-squa…
Burstlike Events in the Z Source Cygnus X-2
van Paradijs, J.; van der Klis, M.; Kuulkers, E.
We have found nine burstlike events in EXOSAT data of the Z source Cyg X-2. Their durations are of the order of several seconds. Within the limited counting statistics we cannot find an indication for cooling during the burstlike events, which would have indicated that they are bona fide type I bursts, i.e., thermonuclear flashes on the surface of…
A Catalog of Far-Ultraviolet Point Sources Detected with the FAUST Telescope on ATLAS-1
Bowyer, Stuart; Lampton, Michael; Sasseen, Timothy P. +1 more
We list the photometric measurements of point sources made by the Far Ultraviolet Space Telescope (FAUST) when it flew on the ATLAS-1 space shuttle mission. The list contains 4698 Galactic and extragalactic objects detected in 22 wide-field images of the sky. At the locations surveyed, this catalog reaches a limiting magnitude approximately a fact…
Gas motions in and origin of the supergiant shell LMC4.
Bomans, D. J.; de Boer, K. S.; Domgoergen, H.
IUE high-dispersion spectra of stars in the supergiant shell LMC4have been used to derive velocities and column densities of absorbing gas clouds. The HI 21-cm profiles for the LMC4region from the LMC data of Rohlfs et al. (1984) have been analysed and interpreted in cloud components. Combining the absorption and emission line data, a detailed pic…
Ulysses solar wind observations to 56° south
McComas, D. J.; Goldstein, B. E.; Bame, S. J. +3 more
In the 25 months since Jupiter flyby, the Ulysses spacecraft has climbed southward to a heliolatitude of 56°. This transit has been marked by an evolution from slow, dense coronal streamer belt solar wind through two regions where the rotation of the Sun carried Ulysses back and forth between streamer belt and polar coronal hole flows, and finally…
Dynamic Processes in Be Star Atmospheres. III. Rapid Multiwavelength Variability in gamma Cassiopeiae
Smith, Myron A.
A review of the characteristics of X-ray emission from gamma Cas suggests various weaknesses with conventional scenarios that invoke Be wind interactions with a putative binary companion. To explore whether this emission might arise instead from sporadic high-energy events on the Be star itself, we have examined the temporal behavior of Voyager 1 …
Late-Time Spectra and Type IA Supernova Models: New Clues from the Hubble Space Telescope
Schmidt, B. P.; Kirshner, R. P.; Wheeler, J. C. +4 more
Calculated late-time spectra of two classical hydrodynamical models for Type Ia supernovae (deflagration model WI of Nomoto, Thielemann, & Yokoi, and delayed detonation model DD4 of Woosley & Weaver) are compared with observations of SN 1992A and other spectroscopically normal SNe Ia, An important new piece of information is provided by ob…
A VIC Color-Magnitude Diagram of the Globular Cluster NGC 6352 From Hubble Space Telescope Planetary Camera Observations
Da Costa, G. S.; Seitzer, P.; Demarque, P. +5 more
The globular cluster NGC 6352, which on the basis of its Galactic position, radial velocity, and [Fe/H] is a member of the (thick) disk system of globular clusters, has been observed to below the main-sequence turnoff (MSTO) using the Hubble Space Telescope. These observations, which were obtained before the repair mission, were analyzed using the…
Molecular H 2 Emission in HH 47A: Hubble Space Telescope GHRS and FOC Observations
Hartigan, Patrick; Raymond, John C.; Curiel, Salvador +4 more
We present Hubble Space Telescope ultraviolet observations of the bow shock at the end of the HH 47 stellar jet obtained with the Goddard High Resolution Spectrograph (GHRS) and the Faint Object Camera (FOC). The GHRS spectrum shows three prominent emission lines of H2 which are produced by Lyα fluorescence and one line that we cannot i…