Search Publications
Hubble Space Telescope/Faint Object Spectrograph Observations of M87:Lyα Emission from the Active Galactic Nucleus
Sembach, Kenneth R.; Canizares, Claude R.; Sankrit, Ravi
The Faint Object Spectrograph on the Hubble Space Telescope was used to obtain spectra of the central region of M87. These spectra cover the wavelength range 1140-1606 Å and have a resolution of ~1 Å. The nuclear continuum is clearly visible in the spectra. The only strong line that is observed is Lyα, which has a velocity width of about 3000 km s…
ORFEUS II echelle spectra: deuterium and molecular hydrogen in the ISM towards BD +39 3226
de Boer, K. S.; Heber, U.; Marggraf, O. +2 more
In ORFEUS II spectra of the sdO star
Heating and Acceleration of the Solar Wind via Gravity Damping of Alfvén Waves
Noci, Giancarlo; Poletto, Giannina; Mullan, Dermott +1 more
In this paper we present a two-fluid model for the heating of the solar corona and acceleration of the solar wind, based on the dissipation of Alfvén waves by gravity damping. This mechanism was proposed by Khabibrakhmanov & Mullan but has not previously been applied in modeling efforts. After extending the Khabibrakhmanov & Mullan theory …
A Detailed Analysis of the Stellar and Nebular IUE Spectrum of the Peculiar ``O VI Sequence'' Planetary Nebula NGC 40
Feibelman, Walter A.
A detailed analysis of archival individual and co-added low- and high-dispersion IUE spectra of the planetary nebula NGC 40 has been performed, using NEWSIPS extracted spectra. More than 50 emission lines and numerous absorption features have been identified, and emission-line fluxes and equivalent widths were measured. Terminal wind velocities fr…
Extension of TYCHO catalog for low-extinction windows in the galactic bulge
Teixeira, R.; Benevides-Soares, P.; Dominici, T. P. +2 more
We present in this work secondary catalogs up to mVal ~ 13 based on the Tycho reference frame (\cite[ESA, 1997]{esa}) for 12 selected low-extinction fields towards the galactic bulge. The observations have been performed with the Askania-Zeiss Meridian Circle equiped with a CCD camera, located at the Abrahão de Moraes Observatory (Valin…
Dust extinction and intrinsic SEDs of carbon-rich stars. II. The hot carbon stars
Bergeat, J.; Knapik, A.; Rutily, B.
The present work is an extension of a recent study by Knapik & Bergeat (\cite{knapik}, henceforth called Paper I) of the spectral energy distributions (SEDs) of about 300 cool carbon-rich variables and of the interstellar extinction observed on their line of sights. The methods were originally developed for Semi-Regular (SR) and Irregular (L)-…
The Use of Gamma-Ray Bursts as Direction and Time Markers in SETI Strategies
Corbet, Robin H. D.
When transmitting a signal over a large distance, it is more efficient to send a brief beamed signal than a continuous omnidirectional transmission, but this requires that the receiver knows where and when to look for the transmission. For SETI, the use of various natural phenomena has previously been suggested to achieve the desired synchronizati…
Overall Pattern Comparison of the FK5 Proper-Motion System withHipparcos
Zhu, Zi; Yang, Tinaggao
We have performed an overall pattern comparison between the proper motions of the FK5 (Fifth Fundamental Catalogue) systems (FK5, Astrographic Catalog Reference Stars [ACRS], and PPM Catalogue) and those of Hipparcos. The global rotation (time dependent) between the two reference frames is found to be different for different stellar samples, depen…
Unbiased image reconstruction as an inverse problem
Pijpers, F. P.
An unbiased method for improving the resolution of astronomical images is presented. The strategy at the core of this method is to establish a linear transformation between the recorded image and an improved image at some desirable resolution. In order to establish this transformation only the actual point spread function and a desired point sprea…
Recent Developments in Quasilinear Cosmic Ray Particle Acceleration Theories
Vainio, Rami; Schlickeiser, Reinhard
Several recent results of quasilinear cosmic ray transport theory are reviewed. It is shown that modelling the plasma turbulence beyond the magnetostatic approximation is most important for a correct description of cosmic ray dynamics. In particular, the effects of finite plasma wave speeds play a crucial role both for the behaviour of the particl…