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The Underlying White Dwarf Accretor in the Dwarf Nova UU Aquilae
Sion, Edward M.; Stump, Michael
We present a high-gravity, solar composition model atmosphere and model accretion disk study of the U Gem type dwarf nova UU Aql. We have identified the far-UV signature of the underlying white dwarf for the first time. Our best-fit model atmosphere to the observed far-UV spectrum in quiescence is 27,000+/-1000 K. The solar abundance high-gravity …
Speckle Observations of Composite Star Candidates
Bord, D. J.; Sowell, J. R.; Hart, D. L. +1 more
Speckle observations are reported for 53 stars with composite spectra selected from the Michigan Spectral Catalogue in an effort to improve the orbits of known binaries and to discover new binaries among this class of objects. The data were obtained using the 1.3 and 2.4 m telescopes at the Michigan-Dartmouth-MIT Observatory and the Georgia Tech R…
Application of Fano profiles to asymmetric resonances in helioseismology
Boumier, P.; Gabriel, A. H.; Thiery, S. +1 more
Parallels are drawn between the asymmetric resonance profiles observed in global helioseismology and the Fano theory for autoionisation profiles in atomic spectroscopy. We show that the underlying physics of the interaction of a discrete resonance with a correlated continuum is common to both systems. The approximate formula normally used for fitt…
Cassini plasma spectrometer observations of bidirectional lobe electrons during the Earth flyby, August 18, 1999
Coates, A. J.; Linder, D. R.; Dougherty, M. K. +4 more
Unlike previous missions to the magnetotail (IMP 6, ISEE 1, ISEE 3, and Geotail), which effectively made observations in the lobe at a single downtail distance, the Cassini Earth swingby allowed, for the first time, near-continuous observations covering a range of downtail distances. Bidirectional electrons are found in the northern lobe, consiste…
AAT Observations of the SL9 Fragment C, D, G, K, N, R, V, and W Impacts with Jupiter: Lightcurves and Imaging
Crisp, David; Spencer, John; Orton, Glenn +2 more
We used the InfraRed Imaging Spectrometer (IRIS) on the Anglo-Australian Telescope to monitor the July 1994 impacts of Comet Shoemaker-Levy 9 with Jupiter. Spectral image cubes were obtained for the impacts of fragments C, D, G, K, R, and W. These data provide time sequences of spatially resolved spectra in K-band (1.98 to 2.40 µm), with a s…
A Large Spectral Class Dependence of the Wilson-Bappu Effect among Luminous Stars
Parsons, Sidney B.
The striking correlation between Ca II K-line emission width and absolute visual magnitude has not previously been well calibrated for stars more luminous than giants. From a sample of binary systems fit to isochrones, we find deviations of more than 2 mag, correlated with spectral class, between these binarity Mv values and the Wilson-…
Infrared spectral classification of OB stars with ISO-SWS
Waters, L. B. F. M.; de Koter, A.; Zaal, P. A.
We present observations of the Bralpha , Brbeta and Pfalpha lines of 16 dwarf and (sub)giant stars in the spectral range O9-B3. The observations were done using the Short Wavelength Spectrometer on board the Infrared Space Observatory, and have a signal-to-noise of ~ 20 to > 150 and a resolving power varying from ~ 1400 to 2100. We compare the …
Low Energy Particles in the Global Heliosphere 2001 2004: 1 to 90 AU
Krimigis, S. M.; Lanzerotti, L. J.; Armstrong, T. P. +4 more
Charged particle instrumentation that will be flying on six spacecraft in the heliosphere between 1 and 90 AU during 2001 2004 will provide a global view of the interplanetary medium that has not heretofore been available. Comparative analyses of the data that will be obtained will provide new understanding of the global evolution of heliospheric …
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 …