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Mid infrared polarisation of Ultraluminous Infrared Galaxies
Siebenmorgen, R.; Efstathiou, A.
The mid infrared polarisation properties of four Ultraluminous Infrared Galaxies (ULIRGs) have been investigated by broad band filter observations with the ISOCAM instrument on board the Infrared Space Observatory (ISO). The wavelength region from 5 to 18 mu m was selected where the emission from the putative torus peaks. We report detection of po…
CLASS B0739+366: A New Two-Image Gravitational Lens System
Pearson, T. J.; Blandford, R. D.; Koopmans, L. V. E. +10 more
We present the discovery of CLASS B0739+366, a new gravitational lens system from the Cosmic Lens All-Sky Survey. Radio imaging of the source with the Very Large Array shows two compact components separated by 0.54", with a flux density ratio of ~6:1. High-resolution follow-up observations using the Very Long Baseline Array (VLBA) at 1.7 GHz detec…
On the determination of the light curve parameters of detached active binaries. I. The prototype RS Canum Venaticorum
Becciani, U.; Lanza, A. F.; Rodonò, M.
Photospheric cool spots are responsible for wave-like distortions observed in the wide-band light curves of close active binaries. They affect the determination of the photometric parameters in eclipsing systems making it necessary to accurately model the spot effects in order to estimate the true luminosity ratio, the fractionary radii and the in…
UV (IUE) spectra of the central stars of high latitude planetary nebulae Hb7 and Sp3
Parthasarathy, M.; Nakada, Y.; Gauba, G. +1 more
We present an analysis of the UV (IUE) spectra of the central stars of Hb7 and Sp3. Comparison with the IUE spectrum of the standard star HD 93205 leads to a spectral classification of O3V for these stars, with an effective temperature of 50 000 K. From the P-Cygni profiles of CIV (1550 Å), we derive stellar wind velocities and mass loss rates of …
Viewing corotating interaction regions globally using energetic neutral atoms
Hsieh, K. C.; Hilchenbach, M.; Czechowski, A. +2 more
We present model simulations to estimate the flux of 25-100 keV energetic neutral atoms (ENAs) that can be expected from charge exchange between the ion populations accelerated at corotating interaction regions and the slow neutral atoms penetrating from the local interstellar matter. The extended structure of a corotating interaction region (CIR)…
On the Wilson-Bappu relationship in the Mg II k line
Badiali, M.; Cardini, D.; Altamore, A. +1 more
An investigation is carried out on the Wilson-Bappu effect in the Mg Ii k line at 2796.34 Å. The work is based on a selection of 230 stars observed by both the IUE and HIPPARCOS satellites, covering a wide range of spectral types (F to M) and absolute visual magnitudes (-5.4<= MV <=9.0). A semi-automatic procedure is used to measu…
The relation between cyclotron heating and energetic particles on open coronal field lines
Laitinen, T.; Vainio, R.
Cyclotron resonance with high-frequency Alfvén waves has been proposed as an ion heating mechanism for producing high-speed winds and large ion temperatures in coronal holes. In the simplest version of the model (cyclotron sweep model), the waves propagate without interacting until they hit a resonance with the plasma ions at distance, where the i…
ISO observations of symbiotic stars. I. HM Sge
Schild, H.; Eyres, S. P. S.; Salama, A. +1 more
We present ISO SWS and LWS observations of the symbiotic star HM Sge. The infrared emission longward of ~ 5 mu m is dominated by a silicate dust shell. There is a number of high ionization emission lines superimposed on the dust continuum. The ISO continuum spectra can be fitted with a single, optically thick silicate dust shell but such a model d…
Spectroscopic Observation of the Planetary Nebula IC 4846
Hyung, Siek; Aller, Lawrence H.; Lee, Woo-baik
A high-dispersion optical (3700-10100 Å) spectrum was secured with the Hamilton echelle spectrograph at the coudé focus of the 120 inch (3 m) Shane telescope at Lick Observatory, with the goal of deriving chemical abundances for the compact planetary nebula IC 4846. We also remeasured the UV spectra from the IUE archive. Diagnostics indicate that …
A Cepheid is No More: Hubble's Variable 19 in M33
Stanek, K. Z.; Macri, L. M.; Sasselov, D. D.
We report on the remarkable evolution in the light curve of a variable star discovered by Hubble in M33 and classified by him as a Cepheid. Early in the 20th century, the variable, designated as V19, exhibited a 54.7 day period, an intensity-weighted mean B magnitude of 19.59+/-0.23 mag, and a B amplitude of 1.1 mag. Its position in the period-lum…