Search Publications
The combination of ground-based astrometric compilation catalogues with the HIPPARCOS Catalogue. I. Single-star mode
Wielen, R.; Dettbarn, C.; Lenhardt, H. +1 more
The combination of ground-based astrometric compilation catalogues, such as the FK5 or the GC, with the results of the ESA Astrometric Satellite HIPPARCOS produces for many thousands of stars proper motions which are significantly more accurate than the proper motions derived from the HIPPARCOS observations alone. In the combination of the basic F…
Chromospheric models for late A-type stars
Catalano, S.; Gouttebroze, P.; Marilli, E. +1 more
The chromospheres of alpha Aql (Altair) and alpha Cep (Alderamin) are investigated. Different semi-empirical model atmospheres are constructed, and the predicted spectra are compared to the observations of the hydrogen Lyman-alpha line (IUE) and carbon (both neutral and ionized) multiplets (GHRS-HST). It is found that chromospheric models at low t…
Streamer Evaporation
Wu, S. T.; Suess, S. T.; Wang, A. -H. +1 more
Streamer evaporation is the consequence of heating in ideal MHD models because plasma is weakly contained by the magnetic field. Heating causes inflation, opening of field lines, and release of solar wind. It was discovered in simulations and, due to the absence of loss mechanisms, the ultimate end point is the complete evaporation of the streamer…
Spatially Resolved Hopkins Ultraviolet Telescope Spectra of NGC 1068
Kriss, Gerard A.; Espey, Brian R.; Grimes, John P.
We present spatially resolved far-ultraviolet spectra (912-1840 Å) of NGC 1068 obtained using the Hopkins Ultraviolet Telescope (HUT) during the 1995 March Astro-2 mission. Three spectra of this prototypical Seyfert 2 galaxy were obtained through a 12" diameter aperture centered on different locations near the nucleus. The first pointing (A1) was …
NICMOS observations of two classic AGNS
Thompson, Rodger I.; Corbin, Michael
Detection of O VII lambda1522 in IUE Spectra of Planetary Nebula Nuclei and Other Hot Stars
Feibelman, Walter A.
We present the first detection of O VII lambda1522 emission or absorption from archival IUE spectra in 14 planetary nebula nuclei and three PG 1159-type stars. The n=5-->6 transition of O VII was determined by Kruk & Werner and observed by them in the spectrum of the very hot PG 1159-type star H1504+65 from data obtained with the Hopkins Ul…
The H2O abundance and star formation history in rho OPH
Olofsson, Göran; Liseau, René
Iso-Lws observations towards a large number of different positions in the core of the rho Ophc are used to place a limit to the abundance of wide spread H2O. From Nlte excitation and radiative transfer modelling the average line spectrum of the rho Ophc, we find X(H2O) < 10^{-6} to 10^{-5}. We interprete these results with…
First Observations of an R Coronae Borealis Star with the Space Telescope Imaging Spectrograph: RY Sagittarii near Maximum Light
Woitke, P.; Clayton, Geoffrey C.; Asplund, Martin +3 more
We describe the far-UV (1140-1740 Å) spectrum of the hydrogen-deficient R Coronae Borealis (RCB) star RY Sgr, obtained near maximum light (pulsational phase ~0.1) by the Space Telescope Imaging Spectrograph (STIS) on Hubble Space Telescope. The far-UV spectrum shows a photospheric continuum rising steeply toward longer wavelengths and two prominen…
HST/STIS ultraviolet spectroscopy of the supersoft X-ray source RX J0439.8-6809
Rauch, T.; Gänsicke, B. T.; Beuermann, K. +3 more
We present ultraviolet observations of the supersoft X-ray source RX J0439.8-6809 obtained with the Hubble Space Telescope Imaging Spectrograph. The ultraviolet spectrum is a very blue continuum overlayed with interstellar absorption lines. The observed broad Lyalpha absorption line is consistent with an interstellar column density of neutral hydr…
Ultraluminous IRAS galaxy 10026+4347
Mao, S.; Boller, Th.; Wu, H. +4 more
We study optical and X-ray properties of the ultraluminous IRAS galaxy 10026+4347. This galaxy is a narrow-line QSO with very strong FeII emission. Three optical spectra were taken over two years. The full widths at half maximum (FWHMs) of the emission lines are constant whereas the third spectrum seems to show a continuum change. Intermediate-ban…