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Fractionation of SI, NE, and MG Isotopes in the Solar Wind as Measured by Soho/Celias/MTOF
Bochsler, P.; Geiss, J.; Galvin, A. B. +9 more
Using the high-resolution mass spectrometer CELIAS/MTOF on board SOHO we have measured the solar wind isotope abundance ratios of Si, Ne, and Mg and their variations in different solar wind regimes with bulk velocities ranging from 330 km/s to 650 km/s. Data indicate a small systematic depletion of the heavier isotopes in the slow solar wind on th…
HST - GHRS observations of CO and CI fill in the beta -Pictoris circumstellar disk
Feldman, P. D.; Ferlet, R.; Jolly, A. +7 more
GHRS-EchA and G160M spectra of beta -Pictoris have been obtained in the 1400-1600 Angstroms range. A detailed analysis of the CO A-X (0-0, 1-0, 2-0) bands and of the CI lambda 1561 Angstroms multiplet is presented. A column density of the order of 2 10(15) cm(-2) is found for both species. For CO, the rotational temperature is found close to 20 K …
A Multiwavelength Campaign on γ Cassiopeiae. II. The Case for Corotating, Circumstellar Clouds
Smith, Myron A.; Robinson, Richard D.; Hatzes, Artie P.
Simultaneous X-ray/UV observations over a full day on 1996 March 14-15 have been made of the prototypical B0.5e star γ Cas using the Rossi X-Ray Timing Explorer satellite and the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope. The GHRS spectra, taken in the region of the Si IV λλ1394-1403 doublet, also permitted th…
BVI CCD Photometry of the Globular Cluster 47Tuc
Stanek, K. Z.; Kaluzny, J.; Krzeminski, W. +1 more
We present BVI photometry for about 16000 stars from a 220 square arcmin field centered 8arcmin East of the center of 47 Tuc. We have identified eight likely blue stragglers located in the outer parts of the cluster. Four of these objects are easy targets for spectroscopic studies with ground-based telescopes. Six candidates for blue horizontal br…
First Results from the Space Telescope Imaging Spectrograph: Optical Spectra of Gliese 229B
Moos, H. W.; Bruhweiler, F. C.; Maran, S. P. +12 more
We report the first Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) CCD spectroscopy of the bona fide brown dwarf Gliese 229B. The optical spectrum shows absorptions of Cs I at 8944 Å and water vapor bands at 9300-9600 Å. Strong CaH, FeH, TiO, and VO bands observed in late M dwarfs are absent from the spectrum of Gliese 229B. Th…
Lyα Absorption Systems and the Nearby Galaxy Distribution
Grogin, Norman A.; Geller, Margaret J.
We study the galaxy number density (smoothed on a 5 h-1 Mpc scale) around 18 low-redshift Lyα absorbers previously observed with HST. The absorbers lie in the foregrounds of Mrk 335, Mrk 421, Mrk 501, I Zw 1, and 3C 273, all within regions where there are now complete redshift surveys to mZw = 15.5. We construct a smoothed ga…
Hubble Space Telescope Observations of the Gravitationally Lensed Cloverleaf Broad Absorption Line QSO H1413+1143: Spectroscopy of the Lyα Forest and Metal-Line Systems
Turnshek, David A.; Monier, Eric M.; Lupie, Olivia L.
The intervening Lyα forest and metal-line absorbers toward the ``Cloverleaf'' gravitational lens H1413+1143 (zem = 2.54, mv ~ 17) are examined along the four individual sight lines using HST-FOS spectra. The observations probe the Lyα forest systems on size scales of up to 4 h-1 kpc (H0 = 100 h km s…
Abundances of UV bright stars in globular clusters. I. ROA 5701 in omega Centauri and Barnard 29 in M 13
Heber, U.; Moehler, S.; Lemke, M. +1 more
Two UV brights stars in globular clusters, ROA 5701 (omega Cen) and Barnard 29 (M 13) are analysed from high-resolution UV and optical spectra. The main aim is the measurement of iron abundances from UV spectra obtained with the HST-GHRS. In addition atmospheric parameters and abundances for He, C, N, O, and Si are derived from optical spectra (ES…
New Hubble Space Telescope Observations of High-Velocity Lyα and Hα in SNR 1987A
Filippenko, Alexei V.; Pun, C. S. J.; Garnavich, Peter +12 more
We describe and model high-velocity (~15,000 km s-1) Lyα and Hα emission from the supernova remnant SNR 1987A seen in 1997 September and October with the Space Telescope Imaging Spectrograph. Part of this emission comes from a reverse shock located at ~75% of the radius of the inner boundary of the inner circumstellar ring and confined …
The spectral variability of the cool hypergiant rho Cassiopeiae
Lobel, A.; Parker, J. Wm.; de Jager, C. +3 more
We checked the change of the effective temperature with the atmospherical pulsation of rho Cas from combined analyses of optical spectra of 1993-95 and IUE spectra of 1979-81. We find an upper range for bigtriangleup T_eff =~ 750 K over a period of 16-17 months. We present a thorough study of the related absorption line profile changes from which …