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Elemental abundances in normal late-B and HgMn stars from co-added IUE spectra V. Mercury.
Smith, K. C.
Atmospheric mercury abundances are derived for a sample of 40 main-sequence, late-B stars, of which 14 are classified normal, and 26 are known chemically peculiar stars of HgMn or related He-weak types. The observational material for this study comprises co-added, short-wavelength IUE spectra encompassing the HgII λ1942 resonance line, coupled wit…
ISO Observations of Interstellar Ices and Implications for Comets
Ehrenfreund, P.; Dartois, E.; Habing, H. J. +4 more
We report on first ISO observations of interstellar ices in the direction of the protostellar object RAFGL 7009S. Due to its extreme extinction this source represents a unique target for the detection of interstellar ices. Identified molecules include H2O, CO, and CO2together with13CO2, CH4, O…
Hot Interstellar Gas in the Irregular Galaxy NGC 4449
Chu, You-Hua; Bomans, Dominik J.; Hopp, Ulrich
NGC 4449 is an irregular galaxy with a moderately high star formation activity. The massive stars in NGC 4449 have given rise to many bright HII regions, superbubbles, supergiant shells, and ``chimney-like'' radial filaments. ROSAT X-ray observations of NGC4449 have revealed four point-like sources and a wide-spread diffuse emission. The spectral …
Widespread water vapour absorption in SGR B2.
Clegg, P.; Caux, E.; Cernicharo, J. +6 more
We report the discovery of widespread water vapour absorption in the 2_12_-1_01_ 179.5µm transition toward the SgrB2 molecular cloud. The data were obtained with the Long Wavelength Spectrometer (LWS) on board the ISO satellite. A raster map centered on SgrB2 made with the LWS grating clearly shows the 179.5µm H_2_O line in absorption …
Hubble Space Telescope Observations of the Dwarf Nova WZ Sagittae: A Very Rapidly Rotating White Dwarf
Szkody, Paula; Sion, Edward M.; Cheng, F. H. +1 more
We present Hubble Space Telescope Goddard High-Resolution Spectrograph G140L spectra of the white dwarf in WZ Sge, exposed during quiescence. Our best-fitting synthetic spectra yield a rapidly rotating white dwarf with velocity Vrot sin i = 1200+300-400 km s-1, white dwarf effective temperature Twd<…
Herbig Haro Objects in the Orion Nebula.
Hartigan, Patrick; Axon, David J.; O'Dell, C. R. +4 more
We have used the Hubble Space Telescope to image two regions of the Orion Nebula in low and high ionization emission lines. There appear to be two main systems of Herbig Haro objects in the Orion nebula - a `North' System is centered slightly north of the BN and IRc2 sources, and a `South' System centered south of the Trapezium stars. The North Sy…
Ultraviolet Emission-line Ratios of Cataclysmic Variables
Kallman, Timothy R.; Mauche, Christopher W.; Lee, Y. Paul
We present a statistical analysis of the ultraviolet emission lines of cataclysmic variables (CVs) based on ~430 ultraviolet spectra of 20 sources extracted from the International Ultraviolet Explorer Uniform Low Dispersion Archive. These spectra are used to measure the emission-line fluxes of N V, Si IV, C IV, and He II and to construct diagnosti…
Adaptive Optics Infrared Imaging Polarimetry and Optical HST Imaging of Hubble's Variable Nebula (R Monocerotis/NGC 2261): A Close Look at a Very Young Active Herbig Ae/Be Star
Fazio, G. G.; Hora, J. L.; Close, L. M. +7 more
We present high-resolution (FWHM = 0.2") near-IR (J, H, and K') adaptive optics images of the Herbig Ae/Be star R Monocerotis. Optical Hubble Space Telescope (HST) WFPC2 PC camera archival images are also presented. For the first time, adaptive optics was utilized to make high-resolution (FWHM = 0.2") IR-imaging polarimetry maps of R Mon. In addit…
Volcanic Resurfacing of Io: Post-Repair HST Imaging
Gilmore, Diane; McGrath, Melissa A.; Spencer, John R. +4 more
In March 1994, we used the newly refurbished Hubble Space Telescope (HST) to obtain global imaging of Io at five wavelengths between 0.34 and 1.02 µm, with a spatial resolution of 160 km. The images provided the clearest view of Io since Voyager and the first systematic observations in the wavelength range 0.7-1.0 µm. We have produced …
The expansion of the envelope of Nova V1974 Cygni and the distance problem.
Chochol, D.; Hric, L.; Pribulla, T. +3 more
Available optical and UV spectroscopic, HST and radio imaging observations of the Nova V1974 Cygni were used to derive a kinematic model of the expansion of the nova shell. The nova shell consists of two major components: an outer fast tenuous low-mass envelope and an inner slow main high-mass envelope. The outer envelope, detected spectroscopical…