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Hubble space telescope observations of the 1990 equatorial disturbance on Saturn: Images, albedos, and limb darkening
Ingersoll, Andrew P.; Baum, William A.; Westphal, James A. +4 more
In September 1990 a major equatorial eruption on Saturn produced a disturbance that spread in longitude until it completely girdled the planet. We report here on 150 images recorded in six passbands with the Wide Field/Planetary Camera (WF/PC) aboard the Hubble Space Telescope (HST) on 17 and 18 November 1990. For comparison, we used HST-WF/PC obs…
Hubble Space Telescope Imaging of the Large-Redshift Gravitational Lens Candidate 1208+1011
Maoz, Dan; Schneider, Donald P.; Yanny, Brian +2 more
Four-color photometry obtained with the Hubble Space Telescope is consistent with the hypothesis that the light from the quasar 1208+1011 (z = 3.8) is gravitationally lensed. Guided exposures taken with the HST Planetary Camera resolve the quasar image into two point-source components separated by 0.476" +/- 0.004". The intensity ratio of the comp…
A Gravitational Lens Candidate Discovered with the Hubble Space Telescope
Filippenko, Alexei V.; Maoz, Dan; Schneider, Donald P. +6 more
We report evidence for gravitational lensing of the high-redshift (z = 3.8) quasar 1208+101, observed as part of the Snapshot Survey with the Hubble Space Telescope Planetary Camera. An HST V image taken on gyroscopes resolves the quasar into three point-source components, with the two fainter images having separations of 0.1" and 0.5" from the ce…
Twin Peaks: IC 4329A and Arakelian 120
Marziani, P.; Sulentic, J. W.; Calvani, M.
New spectrophotometric observations of the Seyfert 1 galaxies IC 4329A and Arakelian 120 are presented. The low-ionization broad emission lines (as evidenced by Hβ) are strikingly similar. The so-called zero peak in the Balmer lines of these objects appears to be both broader than and blueshifted relative to the [O III] λλ4959, 5007 lines. It is a…
Studies of symbiotic stars. V. The dust-free yellow system He 2-467.
Munari, U.; Buson, L. M.
Results are presented of simultaneous photometric and spectroscopic observations of He2-467 in the infrared, optical, and satellite ultraviolet. It was found that the He2-467 star system consists of a G6 III star and a very hot (T of about 2 x 10 exp 5 K), luminous (L of about 5000 solar luminosities), and compact (R of about 0.06 solar radius) co…
Migrating optical depth enhancements in the UV wind lines of the WolfRayet star HD 93131.
Smith, L. J.; Prinja, R. K.
We report on the first identification of migrating opacity enhancements in the ultraviolet wind-lines of a Wolf-Rayet star. Systematic variability is identified in the He II lambda 1640 P Cygni profiles HD 93131 (WN 7), and is interpreted in terms of the formation and blueward migration of discrete absorption features. The properties of the featur…
Galileo and Ulysses dust measurements: Fz Venus to Jupiter
Grün, E.; Kissel, J.; Mann, I. +13 more
The Galileo and Ulysses spaceprobes carry two similar dust detectors through interplanetary space from Venus to Jupiter. We report here on impacts which correspond to dust particles above a mass threshold of about 10-13g for which we have complete records. Between December 1989 and January 1992 Galileo repeatedly traversed interplanetar…
Dynamical Evolution Effects on the Hot Stellar Populations in Globular Clusters
Piotto, Giampaolo; Djorgovski, S.
Results of a study of FUV properties of Galactic globular clusters are presented. The spatially resolved spectra measured with the IUE satellite are used to find indications of color gradients in two clusters with the postcore-collapse (PCC) morphology, NGC 6752 and NGC 7099, but not in the case of NTGC 6093, a cluster with the classical King-mode…
The central star of S 216.
Tweedy, R. W.; Napiwotzki, R.
Optical and high-resolution ultraviolet spectra of LS V + 46 21, the postulated central star of the large, nearby planetary nebula S 216, have been analyzed. From modeling the line profiles, this star is found to have an effective temperature of about 90,000 K, surface gravity log g of about 7, and a He:H ratio of about 0.01. These are as expected…
TYCHO Data Analysis. Overview of the Adopted Reduction Software and First Results
Snijders, M. A. J.; Grewing, M.; Pedersen, H. +15 more
In the Tycho project astrometric and photometric data of about 1,000,000 stars to a limit of B = 12 mag will be derived. The brightest 500,000 stars will obtain magnitudes in two colors BT and VT, the fainter 500,000 usually only one broad-band magnitude T. There is confidence that an accuracy will be achieved about 0.03 arcsec for positions and 0…