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Phase-locked photospheric and stellar-wind variations of θ^1^Orionis C.
Stahl, O.; Wolf, B.; Pakull, M. W. +9 more
We have obtained a long series of optical spectra and new IUE spectra of θ^1^Ori C, the brightest star in the Orion Trapezium and the main source of ionization of the Orion nebula (M 42). With these data, we have improved the accuracy of the period of the optical emission-line variations and the UV stellar-wind absorption-line variations. We find …
The rich spectrum of circumstellar PAHs.
Waters, L. B. F. M.; Beintema, D. A.; de Graauw, T. +10 more
We present observations taken with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO) of three evolved C-rich stars, the post-AGB star HR 4049 and two planetary nebulae, IRAS 21282+5050 and NGC 7027. The spectra are dominated by the well-known infrared emission bands, attributed to Polycyclic Aromatic Hydrocarbon…
ISOCAM observations of the Antennae Galaxies.
Altieri, B.; Cesarsky, C.; Boulanger, F. +10 more
We have mapped the Antennae Galaxies (NGC4038/39) in the 6.7 and 15µm continuum emission using ISOCAM (Cesarsky et al., 1996A&A...315L..32C) with =~5 - 8" resolution. Spectrophotometric observations with the CVF in the spectral range 5.5 to 16.5µm have also been obtained. We compare the distribution of the infrared emission in the …
Solid methane toward deeply embedded protostars.
Prusti, T.; de Graauw, T.; Whittet, D. C. B. +6 more
We report on the detection of an absorption feature near 7.67µ m toward the deeply embedded protostellar objects W 33A and NGC 7538 : IRS9. Comparison with laboratory spectra shows that this feature can be identified as the ν_4_ (`deformation') mode of solid state CH_4_ embedded in polar molecules (i.e., H_2_O and/or CH_3_OH) in icy grain ma…
SWS observations of IR emission features towards compact HII regions.
Heras, A. M.; Kessler, M. F.; de Graauw, T. +17 more
We present ISO Short Wavelength Spectrometer (SWS) grating spectra of six compact HII regions. In addition to strong emission lines from atomic species these spectra display infrared bands attributed to Polycyclic Aromatic Hydrocarbons (PAHs). The continuous spectral coverage of the present observations and the high spectral resolution allow to de…
The heliospheric magnetic field at solar minimum: ULYSSES observations from pole to pole.
Balogh, A.; Horbury, T. S.; Forsyth, R. J. +3 more
The fast transit of the Ulysses spacecraft from the south polar regions of the heliosphere to the north polar regions has allowed us to obtain a unique perspective on the configuration and properties of the heliospheric magnetic field at a time of solar minimum activity. We compare the magnetic field in the northern and southern hemispheres and fi…
What powers luminous infrared galaxies?
Lutz, D.; Genzel, R.; Sturm, E. +8 more
Based on the initial data sets taken with the ISO short wavelength spectrometer (SWS) we present a first discussion of the source of luminosity of (ultra-)luminous infrared galaxies (ULIRGs). By comparison of observations of 2.5-45µm lines to classical starbursts and active galactic nuclei and by modelling of the line emission we show that t…
The 6.0 and 6.8µm absorption features in the spectrum of NGC 7538: IRS9.
Prusti, T.; de Graauw, T.; van Dishoeck, E. F. +6 more
Short Wavelength Spectrometer observations of the 6.0 and 6.8µm absorption features towards the obscured young stellar object NGC 7538: IRS9 are presented and compared to the features of a number of species measured in the solid phase. It is found that while solid H_2_O provides the bulk of the 6µm band, additional absorption is requir…
Pulsation models of δ Scuti variables. I. The high-amplitude double-mode stars.
Christensen-Dalsgaard, J.; Petersen, J. O.
The relations between high-amplitude δ Scuti stars and the much more abundant low-amplitude δ Sct variables are not clear. Both groups have similar periods and seem to have almost the same basic physical properties, although their light-curve characteristics are very different. In the last few years much improved observational data have been publi…
Infrared spectrophotometry of NGC 7023 with ISOCAM.
Palazzi, E.; Perault, M.; Abergel, A. +4 more
We present spectrophotometric observations of the reflection nebula NGC 7023 obtained with the ISOCAM Circular Variable Filter (CVF) in the spectral range 5.15 to 16.5µm. Maps in the 16µm continuum emission and in the Unidentified Infrared Bands (UIBs) have been obtained. The continuum emission peaks at the dense interface between the …