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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 …
Evolution of the aligned structures in z~1 radio galaxies
Best, P. N.; Rottgering, H. J. A.; Longair, M. S.
Hubble Space Telescope observations are presented of eight 3CR radio galaxies in the redshift interval 1<~<e1>z<~</e1>1.3. The optical morphologies of these galaxies change dramatically as the radio size increases. It is shown that this evolution is entirely consistent with large-scale star formation induced by the radio jet, and…
Three-dimensional multiscale MHD model of cometary plasma environments
Gombosi, Tamas I.; De Zeeuw, Darren L.; Häberli, Roman M. +1 more
First results of a three-dimensional multiscale MHD model of the interaction of an expanding cometary atmosphere with the magnetized solar wind are presented. The model starts with a supersonic and super-Alfvènic solar wind far upstream of the comet (25 Gm upstream of the nucleus) with arbitrary interplanetary magnetic field orientation. The solar…
The Subarcsecond Radio Structure in NGC 1068. II. Implications for the Central Engine and Unifying Schemes
O'Dea, C. P.; Baum, S. A.; Gallimore, J. F.
In this paper, we explore the nature of the subarcsecond radio components in the Seyfert nucleus of NGC 1068. The southernmost component (S) is the most likely candidate for the location of the central engine. The integrated Spectrum of this component is flat, and the radio brightness temperatures are T_b_ <~ 3 x 10^5^ K. The radio emission is …
Obscuration of LY alpha Photons in Star-forming Galaxies
Giavalisco, Mauro; Calzetti, Daniela; Koratkar, Anuradha
We present a new study of the correlations between the Lyα emission, the UV extinction, and the metal content in a sample of 21 local, low-metallicity starburst galaxies from archival IUE spectra. We have consistently reextracted all the spectra using the optimal extraction algorithm by Kinney and coworkers, and we have also included galaxies not …
The Variability of Quasars. II. Frequency Dependence
Giallongo, E.; Trevese, D.; Vagnetti, F. +2 more
The variability of 30 PG quasars has been observed in the red band during 3 years. A rest-frame structure function analysis shows an increase of variability with the time interval up to 0.2 mag rms after 2 years. A comparison with the IUE data available for PG quasars shows that the variability increases with the rest-frame frequency at each time …
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…
Combined Ultraviolet and Optical Spectra of 48 Low-Redshift QSOs and the Relation of the Continuum and Emission-Line Properties
Corbin, Michael R.; Boroson, Todd A.
We present combined ultraviolet and optical spectra of 48 QSOs and Seyfert 1 galaxies in the redshift range 0.034-0.774. The UV spectra were obtained non-simultaneously with the optical and are derived from archival Hubble Space Telescope (HST) Faint Object Spectrograph and International Ultraviolet Explorer (IUE) observations. The sample consists…
A Solar Polar North-South Asymmetry for Cosmic-Ray Propagation in the Heliosphere: The ULYSSES Pole-to-Pole Rapid Transit
Simpson, J. A.; Bame, S.; Zhang, Ming
The pole-to-pole fast transit of the heliosphere at ~2 AU from the Sun by the international Ulysses spacecraft has made it possible for the first time to investigate in three dimensions the solar wind, interplanetary magnetic field, and---as reported herein---the global propagation of Galactic cosmic rays and anomalous helium. We use measurements …
Hubble Space Telescope Spectroscopic Evidence for a 1 X 10 9 Msun Black Hole in NGC 4594
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +7 more
The discovery by Kormendy of a M• ~= 109 Msolar massive dark object (MDO) in NGC 4594 is confirmed with higher resolution spectroscopy from the Canada-France-Hawaii Telescope (CFHT) and the Hubble Space Telescope (HST). CFHT measurements with the Subarcsecond Imaging Spectrograph improve the resolution from sigma * = 0."40 to 0."27 Gaussian disper…