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Filament Observations with SOHO Sumer/cds: The Behaviour of Hydrogen Lyman Lines
Heinzel, P.; Vial, J. -C.; Schmieder, B. +1 more
On 21 September 1996, a filament close to an area of enhanced network was observed with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer and Coronal Diagnostic Spectrometer (CDS). CDS provided intensity, Doppler shift and linewidth maps of the region in six lines whose temperature range covers 104 to 106…
ISO-SWS Spectra of OH/IR Stars
Waters, L. B. F. M.; Yamamura, I.; de Jong, T. +2 more
We present the spectra of 5 OH/IR stars observed with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO). The spectra are dominated by dust features, both in the amorphous and crystalline state and illustrate the influence of the mass loss rate on the observed spectral features.
Hubble Space Telescope Wide Field Planetary Camera 2 Observations of the Young Bipolar H II Region S106
Bally, John; Zinnecker, Hans; Rayner, John +1 more
We present narrowband Hubble Space Telescope Wide Field Planetary Camera 2 images of the bipolar H ii region S106 in the Hα line. The high-resolution images show unprecedented detail in the two nebular lobes, including prominent scalloped structure of the emission at the ionization front. The illuminating source of the nebula, S106 IR, is detected…
A comparison of recurrent energetic ion enhancements observed at Ulysses and at 1 AU by IMP 8 and SAMPEX: Ulysses launch until following the first north polar passage
Mason, G. M.; Richardson, I. G.; Mazur, J. E.
During the Ulysses mission, the Goddard Space Flight Center instrument on IMP 8 and the University of Maryland low energy ion composition analyzer instrument on SAMPEX observed recurrent MeV/amu ion enhancements in the ecliptic plane at 1 AU. We identify those IMP 8/SAMPEX events related to the recurrent events observed at Ulysses from its launch …
Spectroscopic and photometric investigations of MAIA candidate stars
Lehmann, H.; Scholz, G.; Hildebrandt, G. +2 more
Including our own observational material and the Hipparcos photometry data, we investigate the radial velocity and brightness of suspected Maia variable stars which are classified also in some examples as peculiar stars, mainly for the existence of periodic variations with time-scales of hours. The results lead to the following conclusions: (1) Sh…
Pulsation Modes in Small-Amplitude Red Variable Stars
Percy, John R.; Parkes, Michael
We have investigated the pulsation modes of small-amplitude red variables with well-determined periods and accurate Hipparcos parallaxes by comparing observational and theoretical Q-values. In our sample of 13 stars, one appears to be pulsating in the third overtone, nine in the first or second overtone, and three in the fundamental or first overt…
The Electron Pressure in the Solar Lower Transition Region Determined from O V and Si III Density-sensitive Line Ratios
Wilhelm, K.; Doschek, G. A.; Warren, H. P. +3 more
We determine the electron density at the temperatures of formation of O+4 and Si+2 ions, which are about 2.5 × 105 and 3.2 × 104 K in ionization equilibrium, respectively. These temperatures occur in the lower transition region of the Sun's atmosphere and allow a test of the often invoked assumption of c…
Planetary nebulae with ISO: A58 and A78 - nebulae with hydrogen-poor ejecta
Kimeswenger, S.; Kerber, F.; Weinberger, R.
We present ISO observations of A58 and A78. Both objects are suspected to have undergone late He flashes (`born-again' nebulae). With ISOCAM we have been able to obtain data of much higher spatial resolution over the wavelength range 4.5-18 µm than has been possible in the past. In order to extract full information from our data we have deve…
HST Spectra of the Jovian Ultraviolet Aurora: Search for Heavy Ion Precipitation
Trafton, L. M.; Waite, J. H.; Gérard, J. -C. +3 more
Ultraviolet spectra using Hubble Space Telescope sampled between 1250 and 1680 Å at spectral resolution <=0.57 Å are reported for characteristically bright regions of Jupiter's morning and afternoon northern aurora. Several observed spectra exhibit sharply enhanced resolution. We interpret this as bright auroral emission foreshortened on the mo…
Beta Hydri (G2 IV): a revised age for the closest subgiant
Lindegren, L.; Vandenberg, D. A.; Dravins, D.
The secular evolution of solar-type atmospheres may be studied through comparisons of the current Sun with old solar-type stars of known age. Among the few such stars in the solar Galactic neighborhood, beta Hydri (G2 IV) stands out as a normal single star with an advanced age. Previous age determinations ( =~ 9.5 Gy) were based on the old ground-…