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White clouds on Io?
Rogers, J. H.
This paper reports rapid changes in the distribution of bright white patches in one region of Io, close to the subjovian point and the caldera Karei Patera. A stable pattern of white patches in this region was recorded by Voyager in 1979. A strikingly different pattern was shown in the first Galileo-G1 image (1996 June). However, the patterns in a…
ISO-SWS Observations of Stars with Unusual IRAS LRS Characteristics
Deguchi, S.; Mizutani, M.; Yamamura, Y.
Observations of 5 stellar sources with unusual characteristics of IRAS Low Resolution Spectra were made with the SWS on ISO. Observed stars are 4 late-type stars with silicate bands and one planetary nebula. Their IRAS LRS contain somewhat unusual features in respect of the 10/18 µm intensity ratio or narrow emission feature from unknown molecular…
HST Observations of Carbon and Hydrogen in DB White Dwarfs
Provencal, J. L.; Shipman, H. L.
The differences in the structure of DA and DB white dwarfs hinge on the asteroseismological analysis of GD 358. However, spectroscopic investigation of this important white dwarf found spectral peculiarities, notably a very low hydrogen abundance and the presence of carbon. These results initiated further investigation of chemical composition of D…
Absorption Features of Ices Toward NGC7538 IRS1
Leto, G.; Strazzulla, G.; Nisini, B. +2 more
In this paper we present a comparison of the observed absorption band at about 660 cm-1 (15.1 µm) toward NGC7538 IRS1 attributed to the bending mode of solid CO2 with laboratory spectra of ion irradiated mixtures.
Flows in Sunspot Plumes Detected with SOHO
Fredvik, T.; Kjeldseth-Moe, O.; Haugan, S. V. H. +4 more
In the Letter, ``Flows in Sunspot Plumes Detected with the Solar and Heliospheric Observatory'' by N. Brynildsen, P. Maltby, P. Brekke, T. Fredvik, S. V. H. Haugan, O. Kjeldseth-Moe, and Ø. Wikstøl (ApJ, 502, L85 [1998]), the following correction should be made:
In the last line on page L86, which reads ``peak line intensity I>=5 are locat…The HIPPARCOS Catalogue
Grewing, M.; Arenou, F.; Lindegren, L. +17 more
The principal observational characteristics of the Hipparcos Catalogue, and a summary of its main astrometric and photometric properties, are presented. Median astrometric standard errors (in position, parallax, and annual proper motion) are in the range 0.7-0.9 milliarcsec (mas) for stars brighter than 9 mag at the catalogue epoch (J1991.25). The…
Measurements of the Cosmological Parameters Ω and Λ from the First Seven Supernovae at z >= 0.35
Filippenko, A. V.; Goldhaber, G.; Goobar, A. +21 more
We have developed a technique to systematically discover and study high-redshift supernovae that can be used to measure the cosmological parameters. We report here results based on the initial seven of more than 28 supernovae discovered to date in the high-redshift supernova search of the Supernova Cosmology Project. We find an observational dispe…
Evolution since z = 0.5 of the Morphology-Density Relation for Clusters of Galaxies
Smail, Ian; Ellis, Richard S.; Dressler, Alan +6 more
Using traditional morphological classifications of galaxies in 10 intermediate-redshift (z ~ 0.5) clusters observed with WFPC2 on the Hubble Space Telescope, we derive relations between morphology and local galaxy density similar to that found by Dressler for low-redshift clusters. Taken collectively, the ``morphology-density'' relationship, T - Σ…
The Centers of Early-Type Galaxies with HST. IV. Central Parameter Relations.
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +7 more
We analyze Hubble Space Telescope surface-brightness profiles of 61 elliptical galaxies and spiral bulges (hereafter "hot" galaxies). The profiles are parameterized by break radius rβand break surface brightness 1β These are combined with central velocity dispersions, total luminosities, rotation velocities, and isophote shap…
Notes on the convection in the ATLAS9 model atmospheres.
Castelli, F.; Gratton, R. G.; Kurucz, R. L.
The mixing-length theory for the convection, as it is used in the ATLAS9 code (Kurucz, 1993a), is summarized and discussed. We investigated the effect of the modification called ``approximate overshooting'' on the model structure of the Sun and of stars with T_eff_ included between 4000K and 8500K, logg included between 2.5 and 4.5, and metallicit…