Search Publications
A search for hot post-AGB stars in the IRAS Point Source Catalog.
Oudmaijer, R. D.
In this paper a first step is made to search for hot post-AGB stars in the IRAS Point Source Catalog. In order to find objects that evolved off the AGB a longer time ago than post-AGB objects discussed in the literature, objects that were not detected at 12 µm by IRAS were selected, The selection yielded 15 objects, of which 12 have spectral…
ULYSSES out-of-ecliptic observations of interplanetary shocks.
Balogh, A.; Forsyth, R. J.; Burton, M. E. +4 more
Interplanetary shocks observed at the Ulysses spacecraft as it traveled from the ecliptic plane to the southern solar pole have been identified and analyzed using both magnetic field and plasma measurements. The latitude dependences of various parameters associated with the shocks (beta, θ_BN_ and Mach number) have been investigated. The direction…
The central stars of the planetary nebulae NGC 7027 and NGC 6543.
Waters, L. B. F. M.; Pottasch, S. R.; Beintema, D. A. +6 more
Infrared spectra of NGC 7027 and NGC 6543 ranging from 2.4 to 45µm were obtained with the Short Wavelength Spectrometer on board the Infrared Space Observatory. A first analysis of these spectra, with the aid of photo-ionization models, is presented. We report the first detection of the [ArVI] 4.53µm and [NeVI] 7.65µm lines in th…
HD 133656: a new high-latitude supergiant.
Trams, N. R.; Van Winckel, H.; Oudmaijer, R. D.
In the course of our study of post-Asymptotic Giant Branch objects, we discovered that the seventh magnitude A supergiant HD 133656 has an infrared excess emission due to cool circumstellar dust, and that its photospheric abundance pattern is population II like. We present a detailed abundance study of the object, and discuss its nature in terms o…
The empirical white dwarf mass-radius relation and its possible improvement by HIPPARCOS
Schmidt, H.
The famous mass-radius relation of white dwarf stars is based on theoretical considerations. The structure of a white dwarf, and thereby its fundamental properties, are deduced from the physical properties of the degenerate electron gas. Numerical computations take temperature and evolution effects into consideration. However, the few cases in whi…
CIV absorption from hot gas inside the supergiant shell LMC4 observed with HST and IUE.
Bomans, D. J.; de Boer, K. S.; Grebel, E. K. +1 more
High resolution ultraviolet spectra obtained with the HST-GHRS of two stars in the direction of the supergiant shell LMC4 unambiguously show absorption by substantial quantities of CIV gas at velocities near the the systemic velocity of the LMC. In combination with the detection of diffuse X-rays from the LMC4 by ROSAT and other supporting data, t…
On the nature of the UV turnup in early-type galaxies.
Alloin, D.; Pastoriza, M. G.; Bonatto, C. +1 more
We study the UV turnup in early-type galaxies from coadded IUE spectra reaching an unprecedented signal to noise ratio. Some spectral groups resulted with strong or moderate UV turnup, while in others it is very weak or absent. We study the relationships of the UV turnup intensity with absolute magnitude, X-ray and Hα luminosities. Galaxies in the…
ISO LWS measurement of the far-infrared spectrum of Saturn.
Ade, P. A. R.; Lellouch, E.; Encrenaz, T. +24 more
The spectrum of Saturn from 43 to 197µm was measured with the ISO Long Wavelength Spectrometer (LWS) during the performance verification phase of the mission. The measurements were made using the LWS in grating mode, with spectral resolutions of 0.29µm from 43 to 90µm and 0.6µm from 90 to 197µm. The spectrum was compa…
The ISO/LWS spectrum of the EGG nebula, AFGL 2688.
Omont, A.; Ade, P. A. R.; Burgdorf, M. +35 more
We present an ISO Long Wavelength Spectrometer (LWS) grating spectrum of the carbon-rich proto-planetary nebula AFGL 2688 between 43 and 194µm. The far-infrared spectrum of AFGL 2688 is dominated by strong rotational transitions of CO which are detected from J=14-13 up to J=23-22. The atomic fine structure lines [O I] and [C II] are not dete…
Coronal radio sounding with Ulysses: dual-frequency phase scintillation spectra in coronal holes and streamers.
Bird, M. K.; Karl, J.; Paetzold, M.
Dual-frequency Doppler measurements of the Ulysses downlink carrier signals were recorded during the spacecraft's 1995 solar conjunction. In this paper we present power spectra derived from phase fluctuations of the radio signals passing through the corona for different solar latitudes. It is possible to (a) distinguish clearly between spectra for…